Green Building in Denver

Simplest Solar System Ever?

2012-02-01T07:06:00.000-08:00

As you may know, I was originally trained as a Solar Engineer (solar water and air heating). In the early 80's, we learned a lot of things on our own because:

1. Manufacturers supplied only components, not complete systems.

2. Because every house is different, every installation is unique, causing mistakes and "issues".

In my opinion, the solar water heating industry has still not matured. Because systems currently cost too much, they aren't being installed as often as they should (which is on every house in the Denver area). For high volume uptake to occur, NREL says the installed price needs to be between $1,000 and $3,000, not the $6,000-$11,000 that you typically find.

Recently, I've been back to learning things on my own, and collaborating with folks like genius Steve Baer.
Some of us have been working on solar system simplification. One simple domestic hot water system that has tested successfully is depicted in the video on YouTube below. If your house has the right configuration, I can install this system for $1850-$2600 with a 5 year warranty. It may be simple, but it requires some high tech to succeed. The collector we must use has the lowest heat loss coefficient of any mass marketed panel.

http://www.youtube.com/watch?v=Q5rKLsJl3cY

CFLs Suck Update

2012-01-30T10:15:00.000-08:00

There is quite a bit of anecdotal evidence that CFLs can cause seizures, rashes and cancer.

http://en.wikipedia.org/wiki/Fluorescent_lamps_and_health

I know some people who "hate the light" from CFLs. Since the color problems have been mostly solved, I think the subliminal flickering is what they object to.

Unfortunately, these problems are also shared with high performance T5 & T8 fluorescent tubes, which are very efficient and economical. Affordable and long lasting LED tube replacement bulbs are coming eventually, so I'd still recommend tube fixtures where appropriate.

Single Family REITs

2012-01-12T14:47:00.000-08:00

If you have been following this blog, you know that I'm advocating the rebuilding of "inner ring suburbs" vs. new subdivision development.

A new report from Morgan-Stanley picks up on a trend I've noticed in the past few years in Southwest Denver:
That rents are now much higher than ownership costs.

Right now is a rare time in history that institutional investors can make an exceptional return by investing in single family homes.

When it's time for the REITs to sell their assets, the idled large homebuilders are the logical buyers.

The Folly of Suburban Greenfield Development

2011-12-10T19:15:00.000-08:00

Green building in Denver isn't just about the home itself. The location of the house can be four times more important for the carbon footprint, making it the single most important topic for this blog and for cities in general. We're not alone in this opinion. The TED prize has announced next year's winner, The City 2.0.

So what to do with all the land that the big builders have reserved for exurban single family homes? Apparently the farmers are buying it back at a steep discount for farming

If this topic gets you agitated, then read this article from Atlantic Cities. It's loaded with links to important studies that support a greener homebuilding paradigm*:

http://www.theatlanticcities.com/housing/2011/12/missing-link-climate-change-single-family-suburban-homes/650/

* the greener paradigm doesn't involve electric cars and photovoltaics in the exurbs. My favorite study is the one that shows people are happier if they can walk, not drive, for daily life.

Lighting Efficiency Summary, 2011

2011-10-23T21:12:00.000-07:00

This list is taken directly from a Martin Holladay article at GBA:

Here are some relative lamp efficiencies:

"Indancescent bulbs produce about 14 to 17 lumens per watt.
Low-cost LEDs produce about 15 to 25 lumens per watt.
High-quality LEDs produce about 40 to 70 lumens per watt.
CFLs produce about 48 to 60 lumens per watt.
T-5 and T-8 linear fluorescent tubes produce about 98 to 105 lumens per watt."

And I just found this increased efficiency LED bulb that kicks out 94.4 lumens/watt:

http://www.amazon.com/Incandescent-Replacement-Illumination-G7-Power/dp/B005FU5406/ref=pd_cp_hi_3

Even though in the article Martin states:

"For now, screw-based CFLs are the best bulb choice for residential lighting.", I think LEDs have just reached the tipping point.

How Does the Demise of Big Builder Magazine Relate to Southwest Denver?

2011-10-09T08:15:00.000-07:00

As I've been saying for a while, destroying greenfields in exurbs is a business model that is slowing down and may end for a long time.

A symptom of this is the announcement of the end of Big Builder Magazine.

If there are any Big Builder types thinking of what next to do with their lives, here's an idea:

Start a land bank in SW Denver, where there are hundreds of homes available for $50k to $100k. These prices don't seem to be going up any time very soon, but they are very competitive with the cost of greenfield lots. Throw in the fact that they are eight times closer to the jobs and entertainment of Denver's city center, and you start to think they may eventually be worth a lot more than those far-flung lots.

Now add in some recent pro-density changes in Denver's zoning code, and you have a pretty compelling business model.

2011 LED Lighting Update

2011-10-07T09:06:00.000-07:00

At $10, LED light bulbs finally make sense for your most-used fixtures.

For green home designers, it means you should stick with medium base fixtures everywhere. The LEDs also operate plenty cool enough for those small closets with shelves. I'm not sure how you will convince the building inspectors, but when incandescent bulbs are illegal, that should solve the problem.

Some folks aren't fully convinced: http://www.greenbuildingadvisor.com/blogs/dept/green-communities/let-there-be-light-gu24-base-cfls-and-leds#post_comments

But these holdouts won't be promoting CFLs much longer. Economics and common sense will bring them around.

And remember, CFLs still suck

Important New Solar Tank from Bradford White

2011-08-15T10:39:00.000-07:00

Bradford White now has a natural gas backup solar tank available for single tank SDHW systems.

Here's the description:

http://www.bradfordwhite.com/images/shared/pdfs/specsheets/507-B.pdf

This means that the old solar rule "You must have a two tank system if your backup is a gas fired tank-style water heater" is now wrong.

Single tank systems ALWAYS win the efficiency and cost contests in every report I've ever seen. There is less area for heat loss, less dollars spent on tanks, less real estate occupied.

But here's the most important (but least obvious) advantage of a single tank system-- if there is solar heat available, it rises up to the portion of the tank that is normally heated with the backup source. Now the heat loss of the backup tank is made up by solar, not gas or electric. In a two tank system, a recirculation pump or thermosiphon would be required to accomplish the same thing.

In theory, I like this new tank. It works simply by placing the temperature sensor higher up in the tank. That means the lower half of the tank will be cool until solar is available. What seems a little magical is how does the heat reach the top of the tank without heating the bottom of the tank, since the burner is still at the bottom?

Well, in an 80 gallon tank, let's just say the burner has heated all 80 gallons by 6am. Now everyone in the household takes their morning shower and uses 40 gallons. Since the thermostat is high up in the tank, it doesn't see the new cold water that is now in the bottom of the tank. The burner doesn't come on, and solar will heat up the bottom of the tank, and if there is excess solar heat for the day, it rises up and helps keep the burner off all night as well.

This latter effect is significant for tank-style natural gas water heaters, because they typically lose 30% -43% of their heat. You definitely want to replace that standby heatloss with solar if possible. Single tank design is the easiest and best way.

There is one missing piece to the puzzle for winter and low solar days. If the top of the tank finally drops below the thermostat setpoint, the burner will fire until the thermostat is satisfied. Since the heat reaching the thermostat must travel through the lower part of the tank, the “solar” section of the tank will be hotter than necessary. Hot water in a solar tank always hurts solar efficiency. B-W doesn’t report by how much, and I think somebody needs to find out. Otherwise, solar curmudgeons will never be convinced to use this tank.

Matt Carlson of Sunnovations is also recommending single tank systems:
http://www.sunnovations.com/sites/default/files/Sunnovations_Newsletter_August2010.pdf

Heat Pump Water Heaters Redux

2011-08-12T23:29:00.000-07:00

Michael Chandler at the GBA reports that manufacturers are on the verge of releasing "split" heat pump water heaters:

http://www.greenbuildingadvisor.com/blogs/dept/green-building-blog/stuff-i-learned-joe-lstiburek-s-house

This is great news for those of us who just couldn't figure out where to put one of today's non-split HPWH:

http://greenbuildingindenver.blogspot.com/2009/08/heat-pump-hot-water-heater.html

What's the Greenest Foundation System for a New House in Denver?

2011-08-09T22:27:00.000-07:00

The conventional wisdom in cold climates for basements (since we stopped hand-digging them) has been "if you need to go down 4' for a crawlspace foundation, why not just dig another 4' and throw in a basement? The marginal costs are very low per square foot, definitely less than building the second floor. Historically, however, unfinished basement square footage is not allowed in the multiple listing service database.

Habitat for Humanity in the Denver area even takes some criticism because they usually choose volunteer safety over basements. No one can get hurt by accidentally falling into a crawlspace foundation. For the same reason, they have eschewed the second floor until recently as vacant land has become scarcer.

My cost analyses, however, are showing me that a frost-protected monolithic slab is more cost-effective than a basement as long as the land is cheap. Once the price of land reaches about $20/sq. ft., then a basement may be required by the homebuying market. In other words, the neighborhood is so expensive that the buyers expect the extra square footage of a basement.

The tipping point in favor of slab-on-grade over crawlspace is that the slab can be the finished floor. Stained concrete is still trendy, bulletproof, and saves at least $3/sq.ft. on your floor system.

My concrete floor is six years old, had zero maintenance*, and looks just like the day we moved in.

The thermal mass and the way it buffers the temperature is just a bonus.

Unfortunately, slabs are all but incompatible with modular construction. Houses from modular builders always have a wooden joist floor system for shipping rigidity, so there's no opportunity for a slab floor.

A Slab is green because:

A slab is much easier and less expensive to insulate properly than a crawlspace or a basement.

No ventilation required, and no water problems if it's a few inches above grade. It uses less money and resources to construct. It has less chance of failure or air quality problems.

The biggest drawback is the lack of easy remodeling.

*Cleaning is not maintenance.

Praise for Swamp Coolers (in Denver)

2011-06-26T16:57:00.000-07:00

We've got a bit of a heat wave going in Denver right now, so I felt compelled to brag a little about my $400 air conditioning system. If you look at this photo closely, you can see that the temperature of the top floor of my house was 59F this morning, after running the A/C all night. Doesn't this seem wasteful? After all, the EPA recommends a 76F setting for your air conditioner.

Well, no, it isn't. My A/C is actually an evaporative cooler which is really just a ventilation fan that passes the ventilation air (3500cfm in this case) through a water-soaked pad. It costs me only $0.80/day (7 kwh/day) to get my house this cold during 90F weather. What many folks don't understand, however, is that when it's hot (over 86F), you shouldn't run the thing during the daytime. It should be off from about 9am to about 8pm, with the windows in the house shut tight. Apparently the swamp cooler manufacturers don't understand this either, or they'd be selling controls with timers at Home Depot.

And I'm not feeling guilty about contributing to global warming, because I'm actually cooling down my neighborhood when the cooler runs.

Earth Advantage Institute's Top Ten List

2011-05-01T07:28:00.000-07:00

Top Ten Green Building Trends for 2011

See my comments in italics as to how these trends pertain to Denver

PORTLAND, Ore., January 6, 2011 – Earth Advantage Institute, a leading nonprofit green building resource and research organization that has certified more than 11,000 sustainable homes, today announced its annual selection of top ten green building trends to watch for over the next 12 months.

The trends, which range from “affordable green” to lifecycle analysis of materials, were identified by Earth Advantage Institute based on discussions with a range of audiences over the latter part of 2010. These sectors included policymakers, builders, developers, architects, real estate brokers, appraisers, lenders, and homeowners.

“Despite market conditions, we have seen the market share for high performance homes increase from 18.5 to 23 percent in the Portland Metro area alone,” said Sean Penrith, executive director, Earth Advantage Institute. “This is a sure sign that the rate of appeal for these homes is increasing.”

1. Affordable green. Many consumers typically associate green and energy-efficient homes and features with higher costs. However, the development of new business models, technologies, and the mainstreaming of high performance materials is bringing high-performance, healthy homes within reach of all homeowners. Leading the charge are affordable housing groups, including Habitat for Humanity and local land trusts, now building and selling LEED® for Homes- and ENERGY STAR®-certified homes across the country at price points as low as $100,000*. In the existing homes market, energy upgrades are now available through new programs that include low-cost audits and utility bill-based financing. Through such programs as Clean Energy Works Oregon, and Solar City’s solar lease-to-own business model, no up-front payment is required to take advantage of energy upgrades.

If you can borrow the money for 6% or less, you will have a better ROI than a Solar City lease. Keep your eye on PACE financing, which adds a solar loan payment to your property taxes.

2. Sharing and comparing home energy use. As social and purchasing sites like Facebook and Groupon add millions more members, the sharing of home energy consumption data – for rewards – is not far behind. The website Earth Aid (www.earthaid.net) lets you track home energy usage and earn rewards for energy savings from local vendors. You can also elect to share the information with others on Earth Aid to see who can conserve the most energy. When coupled with other developments including home energy displays, a voluntary home energy scoring system announced by the Department of Energy, and programs including Oregon and Washington’s Energy Performance Score, a lot more people will be sharing -- and comparing -- their home energy consumption.

XCEL will disclose any of their customers' average bill. Just tell them you want to buy the house and are doing due diligence.

3. Outcome-based energy codes. Existing buildings are responsible for most energy use and associated carbon emissions, but the prescriptive energy codes used in commercial remodels don’t encourage effective retrofitting. Compliance with energy codes is determined at permit time, using prescriptive or predictive models, and actual post-construction may never even be reviewed. Heating and cooling equipment could be faulty or improperly controlled, with significant energy and financial implications. Under outcome-based energy codes, owners could pursue the retrofit strategy that they decide is most effective for their building and its tenants, but they would be required to achieve a pre-negotiated performance target through mandatory annual reporting. The City of Seattle and the New Building Institute have teamed up with the National Trusts’ Preservation Green Lab to pioneer a framework for just such a code, for both new and existing buildings.

There is no way that prescriptive codes can keep up with the technology. For example, when (if) PV costs decrease enough, then site generation of energy has a cheaper life cycle cost than more insulation.

4. Community purchasing power. Neighborhoods interested in renewable energy will increasingly band together to obtain better pricing on materials such as solar panels and on installation costs. The Solarize Portland program was initiated by local neighborhood leaders in Southeast Portland who wanted to increase the amount of renewable energy generated in their area by working together as a community. The program is structured so that the price of solar panel installation decreases for everybody as more neighbors join the effort. Group purchasing creates a 15-25 percent savings below current prices. This group discount, in addition to current available tax credits and cash incentives, gives participants a significant cost savings. In Philadelphia, the Retrofit Philly program leverages contests between residential blocks to get neighborhoods involved in energy upgrades.

5. Intersection of smart homes, “grid-aware” appliances, and smart grid. While many residential smart meters have been installed, the customer interface that will allow homeowners to track energy use more accurately are not yet in place. In the meantime, manufacturers are increasingly introducing appliances that are “grid-aware.” These appliances are endowed with more sophisticated energy management capabilities and timers, offering homeowners machines that monitor and report their own electricity usage and that increase or decrease that usage by remote command. Many machines have timers and can already be manually programmed to run during off-peak hours. These developments will begin forging the convergence of a smart grid infrastructure and the control applications needed to manage energy savings in our buildings and homes.

Xcel and other utilities have mishandled smart grid pilot projects. It will take years of consumer education before this can be implemented, due to current consumer mistrust.

6. Accessory dwelling units. Last year we discussed home “right-sizing” as a trend. However, with fewer people moving or building due to financial concerns, many have chosen to stay put in their favorite area and build accessory dwelling units (ADUs). These small independent units, which can be used for offices, studios, or in-law space, are the ideal size for energy savings and sustainable construction. As detached or attached rental units, they help cities increase urban density and restrict sprawl, while allowing homeowners to add value to their property. The cities of Portland, Oregon, and Santa Cruz, California, have waived administrative fees to encourage more ADU construction.

Denver relegalized more ADUs than any other city in 2010. Unfortunately, the new zoning code also downzoned many older neighborhoods. The net result is that ADUs are still illegal in roughly 80% of the city. Since the code gets major revisions only every 54 years, we're stuck now. Neighborhoods with a strong desire for ADUs can get their zoning changed if a majority of the residents agree. Good luck with that one.

7. Rethinking of residential heating and cooling. Advances in applied building science in the US and abroad have resulted in homes that are so tightly sealed and insulated that furnace-less, ductless homes are now a reality. The increasingly popular “Passive House” standard, for example, calls for insulation in walls and ceiling that is so thick that the home is actually heated by everyday activity of the occupants, from cooking to computer use. Even in ENERGY STAR-certified homes builders are now encouraged to bring all ductwork inside the insulated envelope of the house to eliminate excess heat or cooling loss, and to use only small but efficient furnaces and air conditioners to avoid wasting power. Geothermal heating and cooling, where piping loops are run through the ground to absorb warmth in the winter and cool air in the summer, are another option gaining broader acceptance.

Geothermal for SFRs is losing out to minisplit ductless air-to-air heat pumps due to cost.

8. Residential Grey Water use. With water shortages looming in many areas including the Southwest and Southern California, recycling of grey water – any household wastewater with the exception of toilet water – is gaining traction. Benefits include reduced water use, reduced strain on septic and stormwater systems, and groundwater replenishment. Although many cities have been slow to legislate on grey water use, some communities have increased the amount of allowable grey water use for irrigation. Systems can be as simple as a pipe system draining directly into a mulch field or they can incorporate collection tanks and pumps.

Denver already gets all its water from a low cost greywater recycling system, snowmelt.

9. Small Commercial Certification. 95 percent of commercial building starts in the U.S. are under 50,000 square feet, but the bulk of current certified commercial buildings tend to be much larger. This is in part because of numerous “soft” costs including commissioning, energy modeling, project registration, and administrative time, all of which can be prohibitively expensive for small building owners and developers. To encourage more small commercial projects to go green, alternative certification programs have sprung up, including Earthcraft Light Commercial and Earth Advantage Commercial which have found significant appeal.

10. Lifecycle Analysis (LCA). We know quite a bit about the performance of certain materials used in high performance home and commercial building construction, but the industry has just begun to study the effects of these materials over the course of their entire lives, from raw material extraction through disposal and decomposition. Lifecycle analysis examines the impact of materials over their lifetime through the lens of environmental indicators including embodied energy, solid waste, air and water pollution, and global warming potential. LCA for building materials will allow architects to determine what products are more sustainable and what combination of products can produce the most environmentally friendly results.

Durable materials have a green advantage.

*In the case of land trusts, homeowners do not own the land the home is built on.

http://www.earthadvantage.org/resources/press-room/press-releases/top-ten-green-building-trends-for-2011/

New Passive Solar Domestic Hot Water System Debuts

2011-04-19T22:15:00.000-07:00

There’s a new passively pumped solar water heating system
that greatly simplifies the typical cold climate domestic hot water (DHW)
installation.  http://www.sunnovations.com/

For me, the holy grail of solar DHW is a system with almost
everything missing:

1. No pumps
2. No controller
3. No sensors
4. No electricity required
5. No valves
6. No stagnation or overheating problems
7. No chance of freeze damage (freeze tolerant, at least)
8. PEX allowed
9. No heat exchanger
10. No antifreeze
11. Can use a storage tank purchased at Home Depot

This system provides 1-8, but it does have an in-tank heat exchanger and propylene glycol.   I’m not on my knees, but this is not bad!

It operates by resurrecting the Copper Cricket style geyser pump. They solved overheating with a steamback-like method, and can use anyone’s harp style collector.

Prices are taboo on the company's website.

The CEO, Matt Carlson, explains that "the installed cost varies by region. It is influenced by the cost of labor, competition, shipping cost, configuration of the home, permitting costs, and distributor pricing, etc."

Ballpark prices can be obtained through direct contact, though:

http://www.sunnovations.com/forms/contact-us

Here’s another discussion of how the Copper Cricket worked:

http://tinyurl.com/popsci89

And why it fizzled:  http://www.heatinghelp.com/forum-thread/133419/Steam-Pumping

The patent can be viewed at http://www.google.com/patents/about?id=f0LWAAAAEBAJ&dq=7798140

Xcel Drops PV Rebates!

2011-02-24T13:57:00.000-08:00

Edit:
The rebates have been restored after a 5 week moratorium. (Bad move, Xcel, sudden moves like lifting the rebate can kill an entire industry overnight)

Original post:

This is critical to green residential design in Colorado.

An email from COSEIA:

URGENT: Xcel has suspended its solar program & the market is now 100% frozen. Can you help spread the word about this asap? Feel free to forward (or customize) the following email...
Neal

---

Clean energy is under attack. We urgently need your help.

Last week Xcel Energy suspended its solar program, destabilizing the market for clean energy.

This move has effectively frozen solar sales while customers wait for a possible program restart - with a devastating impact on small businesses and the Colorado economy. We can't let a monopoly choke off competition and curtail clean energy. That's why we need your help.

Mark your calendar: join the Rally for Clean Energy Jobs at the state capitol (west steps) in Denver THIS FRIDAY, 2/25 at 12noon.

We need to see you there to help fight back against Xcel's outrageous activities - and to send a clear message that a monopoly shouldn't be allowed to control the fate of Colorado's clean energy industries and put thousands of jobs at risk.

Can you help spread the word about this event?

THANKS!

Here's some background on this important issue - and why Xcel's actions are so concerning:

- Colorado voters have sent a clear message that they want to increase clean energy and help promote economic development. Building on the success of Amendment 37, there are now 5,300 solar jobs and more than 400 solar businesses in Colorado. Colorado is now the #2 state in the U.S. for solar jobs per capita.

- Xcel Energy is using its monopoly to disrupt the market for clean energy and choke off competition. Xcel is now the 2nd major utility to suspend its solar program. Black Hills Energy in Pueblo suspended its solar program in October, which led to a 90% decrease in solar sales and significant job losses while customers wait for incentives to return. The Colorado economy can't afford a devastating similar crash statewide. An estimated 2,000-3,000 Colorado jobs will be lost by the end of the year unless there is a rapid restart to the state's successful solar programs.

- Every industry needs a stable marketplace to compete. Xcel's Solar*Rewards program was on schedule, slowly ratcheting down incentives as solar costs decreased. Incentives were reduced nearly 50% during the past two years as solar electric costs decreased by 40-50% during the same period. The program has been working. The key was that program changes were predictable, incremental and transparent so consumers and businesses could react.

- Xcel Energy administering its own solar program is a conflict of interest. As a monopoly utility, Xcel has a financial stake in disrupting and destabilizing the clean energy marketplace. A monopoly shouldn't be allowed to pull the rug out from under Colorado's small businesses and put thousands of jobs at risk.

- Xcel is exhibiting a blatant double-standard. If Xcel was forced to change its business model in less than 24 hours without advanced notice or due process it would be crying foul to policymakers and the public about the injustice.

- Colorado needs an independent 3rd party administrator to oversee its solar program. Xcel Energy and Black Hills Energy have demonstrated that they are either incapable or unwilling to ensure a stable marketplace for healthy competition. That's why other states have implemented an independent solar program administrator to avoid these conflicts of interest. Colorado should too.

- The Public Utilities Commission should deny efforts to gut clean energy programs. The PUC should seek to restart Xcel's and Black Hills' solar programs quickly, before any more economic damage is done, and begin a fair and transparent stakeholder process to ensure stable marketplace.

Attend the Rally for Clean Energy Jobs this Friday, February 25 at 12pm, at the Colorado State Capitol building, (west steps) and show your support for clean energy in Colorado and for future generations.

Please forward this email to your friends!

Best regards,
Neal Lurie
Executive Director, COSEIA

Finally a Consumer Friendly Home Energy Rating System

2011-02-15T12:27:00.000-08:00

I've finally found my dream house rating system, which is just like an EPA rating label for an appliance or a car:

http://www.ecohomemagazine.com/news/2011/01-january/energy-labels-a-powe...

I've been saying for years that as consumers get more educated about energy efficiency in homes, the demand for efficient homes will increase, and the selling price of those homes will increase.

Well, I'm tired of waiting*, so this rating system gives the consumers what they need to know NOW.

NOTE: this is a rating system, and by definition, can only be measured on a house that has been built. This will prevent the most insidious types of greenwashing, like advertising a LEED rating before the home has been built.

There isn't any "embodied energy" rating here, but I think a third scale for that would start making this rating system too confusing. The embodied energy of a low energy new home is small enough to be ignored for now. If and when a carbon tax is implemented, that will be reflected in the selling price of the house.

*I realized that until Realtors understand this stuff, most consumers have no hope. I haven't yet met a Realtor who really understands the difference between a KW and a KWH.

energytrust.org_library_forms_ENH_TP_EPS_Certificate_sample.pdf

811.7 KB

Your New Construction Greenbuilding in Denver Checklist

2011-02-09T08:47:00.000-08:00

My top home design recommendations in no particular order:

-Frost protected slab on grade - R20 min perimeter insulation
-R28 min wall, R60 min roof (many methods available, the consensus is to use cellulose)
-Design for a "conditioned attic" bonus room or no attic (flat or shed roof)
-Simple forms, rectangular or square footprint
-100% electric, no natural gas
-No sliding doors or windows, or even exterior french doors
-If you have sunshine available, high SHGC south (and north) windows, solar DHW ($3.5k max)
-Triple pane windows if you can find them at a reasonable price
-Fiberglass framed windows for longevity and other thermal reasons
-DO hire a HERS rater ($1500 max), DON'T waste money on LEED or PH certification
-Photovoltaic system, take advantage of Xcel rebates
-Small, cheap HRV system ($1000 max total) or just a WhisperGreen exhaust fan for ventilation
-Minisplit heat pump or PTHP
-Induction cooktop, small range hood
-PEX plumbing pipe using 1/2" home runs

In a nice neighborhood, upgrades may be desirable. A finished basement is number one, but if you're building today, it will cost a little more than its resale value. The third floor conditioned attic bonus room is cheaper per square foot.

The Multifamily Market Heads Toward a More Sustainable Model- (Small Units in an Urban Location)

2011-01-29T16:46:00.000-08:00

As we come out of the Great Recession, the pent up demand for housing has manifested itself in a steady drop in vacancy rates nationwide. Denver's multifamily market is already superheating, with small class B+ units selling at an all-time high of over $100k each. (Don't try to do a condo split, however, no one will buy a studio condo even for $60k...it's a weird market)

Consumer demand has shifted to green, as a natural economic evolution. Although today's renters may do a lot of recycling, and worry about global warming, but their personal bottom line rules their housing choice, not their carbon footprint. They would prefer to live in a neighborhood close to amenities so they can do without a car, which saves a lot of time and money. And if your neighborhood is lively, who needs a big home if you're never there? So living greener can also be living cheaper.

http://www.multihousingnews.com/features/development/best-bet-for-building-small-units-in-an-urban-location/

As we mentioned last week, this trend will should also start showing up in the single family market since building on smaller lots has finally been re-legalized.

Denver's Zoning Now on the Cutting Edge

2011-01-18T01:04:00.000-08:00

By now, anyone studying urban planning knows that cities brought wasteful sprawl upon themselves through idiotic policies, culminating in the "greatest mis-allocation of resources in the history of the world"

If cities are to heal themselves, we are unfortunately at the mercy of the same species that got us here, the zoners and planners.

The City of Denver recently adopted a new zoning code after a six year process. A lot of anti-sprawl policies were incorporated, however, some "neighborhood preservation" policies were included that tend to be anti-density and therefore pro-sprawl.

Rewriting the zoning code is difficult, because it's like answering the question, "How will our great grandchildren live, work, commute, and what do they want their city to be like?" So Denver has taken a stab at it, and in some ways we're on to something.

A recent article predicts that the housing market will help revive our economy, but it's not your father's housing market anymore:
http://www.washingtonmonthly.com/features/2010/1011.doherty-leinberger.html

" the Great Recession has highlighted a fundamental change in what consumers do want: homes in central cities and closer-in suburbs where one can walk to stores and mass transit. Such “walkable urban” real estate has experienced less than half the average decline in price from the housing peak."

Denver has responded to this change in the market by legalizing carriage houses for a few thousand lucky homeowners, and introducing tandem house zoning for some of the neighborhoods that used to be zoned for duplexes (R2).

During the recent real estate boom, many reasonably nice homes in gentrifying R2 neighborhoods were being demolished to make way for profitable duplexes. Due to the limitations of the old R2 zoning, building a duplex was formerly the only way homeowners and infill redevelopers could take advantage of the changing demand.

Under the new tandem house and carriage house zoning, a detached new home can be built to the rear or side of the lot without having to scrape the old house. In fact, in the present economic climate, it would be very risky to scrape a performing asset and invest $500,000 to $1M in a speculative duplex. Very few other cities now offer this new option, but those that do will have a clear economic development edge. The livability of these neighborhoods will gradually improve, and home values should follow.

The Advantages of Neighborhood Photovoltaics

2011-01-09T13:02:00.000-08:00

Here are three reasons to like PV mounted on Denver houses, even though it's expensive:

1. Transmission losses - - Although grid-tied PV needs a functioning grid, most of the PV kilowatthours generated at a PV-equipped house stay in the neighborhood and aren't diminished by transmission losses which are usually quoted at 30%.

2. Autonomy - - Let's say you are building a spec house that you want to have low net energy usage. If you install PV, you have added value to that house. If Xcel invests directly in wind energy, that doesn't help you or your buyer.

3. Utility power outage avoidance - - Once PV market share reaches a crucial point, the Xcel will see the potential of outage avoidance that distributed PV inherently has. At that point they will start providing direct inverters and distributed batteries. Utilities receive big rewards for reducing outages.

In Colorado, Xcel is required by law to reach 30% renewable energy by 2020. Neighborhood PV is one of the top 3 ways this will happen, partly because it's easy and incremental compared to larger, more cost effective but cost intensive measures.

Is a Renewable Energy Portfolio Standard an artificial incentive? Of course it is, but until a carbon tax is implemented, there is no other incentive to reduce the use of fossil fuel.

DOE Proposes "Home Energy Score"

2010-11-30T20:23:00.000-08:00

The recently released DOE proposal for home energy ratings is getting closer to what's needed.

As I mentioned last month, the LEED system falls short of usefulness, and the best rating should be in dollars. The DOE system is in dollars, all right, but they are unfortunately using savings, not cost. Home size and "average energy cost of a home without upgrades" needs to GO AWAY. Give us a standardized yearly energy cost for this house, period. It's much simpler, and ultimately much more useful for everyone.

Should We Regulate the Size of Homes Because Big Ones Aren't Sustainable?

2010-10-27T09:28:00.001-07:00

This debate is really simpler than it seems. Dollars are the units with which we can measure and compare everything in a home’s cost. The home uses more land? That equals more dollars in purchase price, property tax, storm runoff fees, etc. It uses more resources to build because it’s bigger? Well, it costs more. The only thing that can improve the accuracy of dollars is a carbon tax that is allocated and implemented perfectly. I realize that won’t be easy.

Recurring costs are a little more difficult. That’s why the EPA created a standard MPG rating for cars, and the Energy Guide rating for major appliances. With them, people could compare their future costs of operation of their purchase against the other competitive products.

I submit that the only worthwhile rating system for homes will be in dollars per year. An accurate HERS score can be converted to $/yr with a standard set of conditions.

Another significant metric for a house is the cost of transportation incurred by the residents. Walk scores and other ratings can be standardized and converted to $/yr, and reported on the MLS. This is already starting to happen.

Now, with a purchase price and a $/yr rating in hand, the consumer will be motivated to buy small, because it’s cheaper. If they can still afford a 3,000sq.ft. house, they should be able to buy it, there is no reason to put an artificial cap on size. Markets forces work well if the consumer is educated.

Unfortunately, LEED scores and Energy Star ratings are a confusing mess: http://greenbuildingindenver.blogspot.com/2010/10/leed-for-homes-rating-system.html

The Location of Your Low Energy House

2010-10-18T09:10:00.000-07:00

Well it's the Denver area, yes, but what makes a low energy location?

According to this article the location is the MOST important factor in low energy homebuilding: "Households in downtown Chicago produce one-quarter the greenhouse gases of households in nearby suburban Kane County"

What if, all of a sudden, say, like, in 2011, "production" homebuilders stopped concentrating on tearing up farmer's fields and building new infrastructure for new housing, and started concentrating on rebuilding run-down neighborhoods closer to the city center?

Hmmmm..........

Just possibly the biggest single step toward halting global warming.

As mentioned before, the trend has begun on vacant lots in Philadelphia. Philly has a strong enough economy to support infill like this. But we're not seeing much of this anywhere else in US. In the rust belt, where vacant lots are available, cities like Detroit are on life support. Job growth is really the only driver of new construction.

Denver has a little bit of job growth, and homebuyers are learning more about these issues everyday. One day in the near future, a young pregnant couple will contact a neighborhood redevelopment company in a neighborhood like Villa Park and not even think of taking a drive out to the Wheatlands , even though the prices are tempting.

Stay tuned.

Water Conservation in Denver

2010-10-18T02:47:00.000-07:00

I've not posted any prior recommendations about water usage, primarily because I'm an energy engineer, not a water engineer. However, I was reading something the other day that said Denver's water usually beats out bottled water in taste tests. Elsewhere, I read that 60% of our water usage is for landscaping. WOW. We residents are thoughtlessly spraying the best drinking water in the WORLD on our lawns.

Then the announcement came that our water rates may increase sharply , so I figured it was time for a post about water and a long-term experiment of mine.

For fun and profit, I invest in Denver real estate, so water costs and landscape maintenance costs are very important to me. Therefore in 2005 when we acquired a house with a dead front yard, we decided to till out the weeds, place down weed barrier, and cover it with mulch. For the whole front yard, this cost $450 including mulch, and took one day with two laborers. In recent years, free mulch from recycled trees has become common.

This simple project saves about $140/year in water, and $200/year for mowing and maintenance. This particular yard doesn't look nice, but there are no weeds at all:

A dirt yard doesn't look any good either, but you still have to mow the weeds that sprout it if you have a rainy spell, and you get a lot more mud tracked into the house:

We've also experimented with a few drought tolerant plants, and found cactus can be grown without a drip watering system. Pea gravel makes for a better play area and lasts longer, but it is more expensive than free mulch.

History Lesson:

During the drought of 2003, Denver Water (DW) begged us to reduce water usage, and invoked watering restrictions that we followed successfully enough to reduce overall usage by over 40%. DW promptly rewarded our diligent efforts with a sharp rate increase. See, when the number of gallons of usage goes down, the infrastructure and management costs of water distribution must go up on a per gallon basis. Gee thanks, DW.

The LEED For Homes Rating System

2010-10-05T22:51:00.000-07:00

I've been watching from the sideline, stubbornly NOT going for LEED qualification. In building code terms, LEED is far too prescriptive and not performance oriented. Throw in "too complex for real customers" and too expensive, and what you have is nearly worthless.

Here's a solution I've been mulling:

1. Let the building departments adopt the 2009 energy code as they wish. Then STOP any code changes forever, except for safety items. The technology is still changing too fast to attempt to follow it with prescriptive code "improvements". Another reason for freezing the code is to prevent those pesky unintended consequences that aren't even discovered for 20 years. (see Solar Driven Moisture in Brick Veneer at BuildingScience.com)

2. Then let builders build as they see fit. Good ones will keep improving the sustainability of their product. (If you care enough to be reading this blog, you're probably one of the good ones)

3. Here's where we replace prescriptive with performance: You can't get any sort of LEEP (Leadership in Energy Efficiency Performance) rating PRIOR to building anything. To get a LEEP rating, the home must have a simple Web-based monitoring device installed for at least one year. The cost of this should only be $1000-$3000, it only needs a handful of measurements, some of which are already there, like kwh consumption, water consumption, gas consumption. Add two indoor temperature readings, hot water tank inlet and outlet, outdoor temperature north side of house and south side of house, major appliance electricity consumption, etc.

This data can then be used to "normalize" the performance results. The square footage of the house is completely left out of the normalization calculations.

4. The LEEP rating is in dollars, the only unit that makes sense to everyone. (Just like a yellow EPA EnergyGuide label for appliances). A true net zero energy house gets a LEEP rating of $0/yr. If you put on excess PV panels, and the utility pays you for your excess production, then your LEEP rating can be calculated to equal what the utility pays you for the year, and is negative, say -$200/yr. A 1000 sq. ft. home built to 2009 code minimum might get a rating of $800/yr. A 2000 sq. ft. home built to 2009 code minimum should perform a little better per sq. ft. than the 1000sq.ft. home, so it might get a rating of $1400/yr.

This performance rating will always guide the builder in the right direction.

5. The other non-energy efficiency related metrics can have their own rating, such as LEEPdurability, and LEEPwater. A near-zero maintenance house might have a LEEPdurability rating of $30 per year, while a house that needs painting and new light bulbs often would be rated at $300/yr. Again, the LEEPwater rating is in $/yr. Oh yeah, don't forget LEEPembodiedenergy. That could be in kwh.

The ratings are thus understandable, simple, standardized, and allow the builder his own solutions rather than any suggested by LEED.

Eventually these ratings will be meaningful to buyers, and that's when the builders learn they must generate good ratings. That's what I like, market forces in play instead of federal policy!

Since this is so similar to the appliance rating program, the LEED officials must have studied the method, but I can't figure out why they rejected it.

The 100k House in Philadelphia

2010-09-27T07:45:00.000-07:00

I've been a fan of the 100k house website for almost 3 years. Chad Ludeman has created an innovative home building and marketing business model, an accomplishment that no large builder in America could ever do.

One recent post sums it up: High Performance Houses

They've nailed it, pure and simple. Contrast it to a subdivision that was nixed by Golden. Golden has no idea of what it really wants, but they had this feeling they didn't want this. Over time, they'll understand that they want 100k houses and neighborhoods.

Does anyone else besides me think Denver is ready for something similar to 100k? The biggest difference in the two markets is that Philly has thousands of low-cost vacant lots ripe for redevelopment. In Denver, a vacant lot in a good neighborhood doesn't exist, so scrapeoffs in lower tier neighborhoods may be necessary. Let's finish the infill process in Denver and scrape or renovate worn-out houses as required before we tear up irreplaceable open space in Golden.

Their list of innovations really covers every phase of the business, except maybe the use of realtors. Lots of folks thought realtors would become obsolete because of the internet, and it just hasn't happened, and doesn't look like it will happen. Postgreen (the 100k development company) however, has pre-sold a high percentage of their homes. This means that they haven't really needed the conventional realtor relationship.

Smart Grid City Update

2010-08-30T08:41:00.000-07:00

Well, unfortunately, Xcel and the PUC have really bungled the potentially exciting deployment of the Smart Grid City prototype in Boulder.

The whole business model for Smart Grid in Colorado is strange because it's a monopoly trying to save it's customers money.
The PUC tries to regulate against Xcel ripping off their customers, but they have almost no directive to promote investment now if it saves money in the future. Add to that some customer resistance to smart metering because it is viewed as an invasion of privacy, and you get a difficult if not impossible implementation.

Why do we care so much about the Smart Grid? Because if TRUE electrical costs could be accurately accounted for and allocated, a residential solar photovoltaic system can be shown to be a better investment than it currently is. We are firm believers in the theory that many small investments in renewables and efficiency can make faster and more nimble improvements in the US's overall energy problems. Big ideas and large projects take much longer to implement, because they are big. The large amount of capital required slows down the process too much, even if the ROI is significantly better than small projects.

If your home-based PV system gives you a return of 5%-15% on your money, millions of homeowners will quickly enter the green energy market as investors. Even if they have zero cash, they can partner with a 3rd party such as SunRun to get a system installed.

We have lots of conservative friends who even think PV is a good investment.

Although we were hoping that the Smart Grid could reduce PV system size, PV system cost has been dropping steadily, so this good news takes the sting out of Xcel's big fumble.

The Latest on Practical LED Lighting

2010-07-25T02:52:00.000-07:00

Product availability is really changing fast. Last fall's offerings at Sam's Club and Costco no longer exist. So if you need LED lighting right now, the optimum solution is at Home Depot, "while suppplies last":
HD Online LED bulb This bulb is bright enough at 428 lumens, but a little pricey at $20. But it's by far the best value as all the other LED bulbs that are this bright will set you back $30-$70 each. And get this, it's guaranteed to last for 46 years (vs 7 for CFLs). Other important features are that it reaches full brightness immediately (unlike CFLs) and is dimmable (rare for CFLs).

I have decided to concentrate on standard medium base screw in bulbs, since they will fit the most economical and the most common fixtures.

Competition for Window World

2010-07-21T11:26:00.001-07:00

Apparently another company is trying to compete head-to-head against Window World:
Denver Post Ad for Clear Choice

Careful, service companies like this always try to upsell you on anything they can. Stick to your guns if price is the most important thing to you.

In order to get windows that qualify for the Energy Star rebate, expect to pay significantly more than the $185 shown in this ad. Even if that eats up the whole rebate, remember you should save money every month because you will have a better window that loses less heat.

Window Retrofit Redux

2010-06-09T16:26:00.000-07:00

In this post, I'm speaking as a home rehabber only. The window solution for the actual homeowner who lives in their home could be different.

I fix homes to resell. The windows must look really good and work perfectly. Thermal performance isn't that important, but most buyers will pay a little more for double glazed windows. If there are some windows that don't open and close, the home inspector will find it. Then the buyer will probably ask you to fix it, or at least give a credit of about $200 per window.

The homes I fix average about 70 years old. They either have the original wood windows or vinyl replacement windows. 90% of the original wood single hung windows work BADLY. If the vinyl windows are over 10 years old, yes, there is some maintenance and parts replacement required. This work costs about $50 per window.

The rehabilitation of the original wood window with about 10 layers of paint on it will cost about $200, and it won't be as tight as a new vinyl window. It will also still be a single glazed non low-e window that tends to cause some thermal comfort problems in that room.

You can add storms to the inside or outside, but 90% of those are lost or inoperable after 20 years. With thoughtless tenants, this can drop to one year. Cost is irrelevant here, because they don't hold up long term.

I have tried all these different scenarios, and new windows are really the only option. When the home is to be resold, it unfortunately turns out that the cheapest window is the most cost-effective. Consumer education may eventually change this. In some munincipalities, the home must be updated to the new energy code whenever it changes hands. That also solves the problem but adds the other problem of forcing the new price of the house to be much higher, or cause the rehabber's margin to be slimmer. Too much government meddling, IMO.

I was particularly disappointed in the wood window restoration route. Yes, the windows worked again, but they still looked BAD. They were simply too far gone for restoration, and that's the case in 80% of the homes I rehab.

In summary, the window must operate, the payback period is irrelevant. $250 each for new windows is worth it, but I don't spend more than that on my rehabs since it would be wasted.

In the Denver area, another great company for replacements is Gravina. They offer a triple pane window that won't break the bank.

Walls for New Construction, State of the Art from Betsy Pettit

2010-05-20T05:07:00.000-07:00

I've built two homes with SIPs. Things didn't go quite as well as I envisioned, so I've been planning to try a double stud wall (not staggered stud) on the next project. My personal lessons learned to this point follow the same arc that Postgreen Homes has documented really well.

There were still a couple of fussy details about double stud design that were bothering me:
1. In order to cover the exterior insulation around the foundation/basement wall, the outer stud has to be cantilevered out too far.
2. Building a double stud wall is too much like framing two walls, which implies double the framing cost.

Building Science Corp and Betsy Pettit, AIA, have come to the rescue in the latest issue of the Journal of Light Construction (JLC):

They're promoting, and have tested, an Advanced Framing wall sheathed with foam. The innovation is the method to support the siding, 1x3 furring strips are attached to the stud wall with 6" screws. This furring is easier, cheaper and better than another stud wall.

Buying New and Retrofit Windows in Denver

2010-05-16T21:54:00.000-07:00

You really only need to know two words on this topic: Window World

Call and ask any company how much they charge for installed windows, they'll say, "let us send out someone to measure, and we'll give you a quote". Fair enough, but you've just committed to one hour with some likeable guy who doesn't value your time that much.

With Window World, just count your windows, then multiply by $250. That's awesome. Of course, they have some options, some of which you need in order to receive the 30% federal rebate. Note that they don't even care about the size. Some windows are bigger, and some smaller, they figure.

As good as they are, you may find confusion when it comes to that all important SHGC number I keep harping on. (Some other guys have started major harping as well )

It just doesn't matter that much. You need some affordable windows NOW that actually go up and down and close tightly. Your south windows are shaded by your neighbor's trees anyway.

So I say go with whatever you can afford.

No Posts in April

2010-05-16T21:51:00.000-07:00

Global warming has obviously been cured in Denver. So I was skiing a lot, and not worrying too much about saving the planet.

More on Low e "Solar" Windows

2010-03-27T20:26:00.000-07:00

If you've been following along, you may have learned how important it is to have high a SGHC rating on your south facing windows in a passive solar house. I have also complained about how clueless American window manufacturers are on the subject.

All that is still true, but Martin Holladay of the GreenBuildingAdvisor has compiled a helpful list of the Canadian suppliers that understand the issue. Even though Home Depot may not have these windows, you should be able to get them shipped to you. Fiberglass frames and triple glazing also add value to your project, and are usually worth the extra money. Fiberglass ensures you won't need to replace them in your lifetime. Triple glazing not only reduces heat loss all the time, it prevents most condensation problems even when you live in Denver and crank up the humidifier when it's zero degrees outside.

Denver No. 7 on ‘Green-Cities’ List

2010-03-16T01:43:00.000-07:00

A pretty good showing on another one of those "green lists".

Denver Business Journal

Where does Denver need improvement? In a word, traffic.

As you know, Denver's light rail system is set to become one of the nation's most extensive. The planning for this goes back about 20 years, so kudos to everyone in the region who recognized the problem in time to make a dent. Portland is one of the few cities with better mass transit than us, and it's #1 on the list.

Portland re-legalized ADU's a long time ago, and Denver is doing the same this summer if the new zoning code is approved.

Traffic is mostly a peak-period problem, so improvements can be made without widening highways (again).
If you are looking for a personal solution to this problem, sell your house in the suburbs ASAP and move to a transit adjacent neighborhood before prices get too high. Other options include telecommuting, bike commuting, and getting up early or coming home late.

Car sharing is growing: http://www.occasionalcar.com/
This is a great private sector solution that is much cheaper than owning your own car. Occasional Car has grown from two cars to eight in just over a year.

If you already live in a walkable neighborhood, you should check out this math:

1. Sell your car and save $300-$2000/month
2. Clean up and rent out your garage for $100/month. (An idea not really allowed by the new zoning code)
3. Join Occasional Car for about $50/month.

You're ahead by at least $350/month!

Heat Pump Progress and More Options

2010-01-31T19:01:00.000-08:00

Here's a heat pump water heater that can be placed in a different place than the water storage tank. That might fix the awkwardness of most HPWH applications. A garage, unused basement room, greenhouse, or even outside might make sense.

Also, here's a brand new DC minisplit heat pump that possibly could improve efficiencies.

Zoning Code Update

2010-01-22T10:54:00.000-08:00

"Final Release" of Denver's new zoning code has now been posted:
www.newcodedenver.com

ADU's have been identified as the most sustainable feature in the new code. Not only do they provide some urban housing that should get many cars off the streets, they are the perfect place to put active solar. Note that passive solar access is impossible to provide except on the south end of every block.

Draft 4 allows for the 2-story ADU's that are needed to get solar systems up and out of the shade. As usual, the buyer of solar needs to be aware of the neighbor's trees so that his new system won't be shaded.

More Solar Access in Denver

2009-12-18T16:10:00.000-08:00

Chris Kennel, a thoughtful resident of Southeast Denver, recently submitted his thoughts to Doug Linkhart on the solar access issue:

"At the Thursday Nov. 19 council meeting I spoke with some advocates of solar access because I plan to install a photoelectric array on my roof and am curious about their ideas. Every solar access advocate I spoke with seemed well-meaning, but I didn't find that any of them had thoroughly considered the implications of their plans. That is why I have chosen to write this letter to you.

The four types of solar access that I heard the solar access advocates describe were:

1) passive solar (sunlight entering windows of their homes)
2) solar hot water panels
3) gardening
4) solar electric (photovoltaic) panels

Each of these solar uses functions differently at different times of the year and therefore has different requirements in terms of access to the sun. This means that a one size fits all approach would either not address each area appropriately or be totally overkill for some areas.

Lets look at each area, starting with the most restrictive one: passive solar. Passive solar, used for heating and lighting is most beneficial when the sun is low in the sky in the winter. In the summer, passive solar is unwanted since it adversely affects indoor comfort and raises the cooling costs of a home. If people want direct sunlight in their first story windows during the winter months, then it
would preclude the design of most of our existing city blocks. In the morning during the winter months, the sun is so low in the sky that an object 2 feet high will cast a shadow 10 feet long at 8 am in the morning. At noon, when the sun is highest, the same shadow would be created by an object that's about 5 feet tall. This means that if someone has a window on their first floor, the roof or gable of neighboring single story house that's 10 feet away to the south would very likely shade its
neighbor to the north. To get unobstructed winter light into a house at noon would require the neighbor's house to be located at least 20 feet away if it's a single story. For morning light, the neighbor would have to be about 40 feet away, and this gets even larger if the southern neighbor's home is a two story.

The second most restrictive solar access issue is rooftop solar hot water panels since these are often used for winter heating. For solar panels, the sun is most effective between 10 am and 2 pm. Two single story houses would be fine close to each other as long as the southern neighbor doesn't have a gable facing the north neighbor. If the southern neighbor has a gable or a second story it would
have to be about 26 feet away from its single story neighbor to avoid shading the rooftop panels during part or all of the 10 am to 2 pm timeframe. If the southern neighbor has a two story gable roof facing the north then it would have to be about 40 feet away.

The third most restrictive solar access issue is gardening. This activity usually happens during the summer months when the sun is higher in the sky, and most sun-loving plants like tomatoes require about 8 hours of sunlight per day to thrive. A single story house would cast a 15 foot shadow and a 2 story house would cast a 25 foot shadow during parts of this timeframe. For gables facing north add another 7 feet to these numbers. People with large lots should be fine, but narrow lots would
receive too much shade for the most sun-loving plants. People with narrow lots could grow plants that tolerate partial shade since from 10 am to 2 pm the shadows from the worst case scenario, a two story house with gable would only cast a 14 foot long shadow.

The most flexible solar access issue is photovoltaic panels. These panels function most effectively in the summer months when the sun is more direct and intense. During the winter months, their output is substantially reduced, so winter solar access shouldn't be over prioritized. Photovoltaics function best from 10 am to 2 pm, and it's unlikely that even a two story neighbor would shade the roof of a single story house to the north during this timeframe in the summer. The more likely
source of shading is from a chimney on the homeowner's own house or a tree. Photovoltaic panels have a weakness in that if any part of a single panel gets shaded, it knocks out the entire panel and in many cases the entire array or branch circuit. Even a leafless deciduous tree in the winter can cast enough of a shadow to knock out a photovoltaic panel. So if photovoltaic panels are given some special status with regard to solar access then it may result in severe tree pruning and even removal, especially to the city's larger and older trees.

Since trees have many benefits, it seems important to exempt them from any rules regarding solar access. Otherwise neighbors will be trying to trim the trees that other neighbors or the city (via parks and greenbelts) own. Even at my house I have some trees that cast shadows over 100 feet long during the winter months, and my trees are only medium sized. I live in a suburban neighborhood so these trees don't affect my neighbors much, but medium sized and larger trees in an urban neighborhood could conceivably cast shadows across four or more lots.

Although solar access sounds nice in theory, creating solar access rules in excess of our current bulk planes is certain to cause a lot of problems. For the group of of Denver residents who place a premium on solar access (and I am one of them), the best and easiest solution is to choose a site that has a park, street, drainage ditch, or other form of undeveloped open space to the south. A second option is to buy a house that's located on the northern most part of its lot.

Not all homes in Denver are equal in many regards, and solar access shouldn't be viewed as a right but rather as a feature. Although I might like my suburban house to be within 5 blocks of a light rail station, a park as good as Washington Park, a bike path, stream, and an excellent coffee house, I can't expect the city to give me all these things. Solar access is similar. Solar access is a function of location, topography, and the direction a home is pointed. As such it has value to some people, but it cannot be equal throughout all of Denver.

For people who do not want to move to a home that has good solar access, there are alternatives. Instead of photovoltaic panels, they can buy renewable power through Xcel energy's wind source program. People who want fresh, local produce can join a CSA (community supported agriculture), participate in a community garden, or visit the farmers' markets instead of planting their own gardens. If someone suffers from SAD (seasonal affective disorder) in the winter they can buy a light therapy box (my wife and I have one and it works great) instead of relying on passive solar light.
Lastly, people who want to reduce their heating costs can better winterize their homes as an alternative to using solar hot water panels or passive solar designs. Better winterization will also make a house more comfortable and energy efficient in the summer. All of these are good options for people who do not have the guaranteed solar access they wish for. It's likely that they've chosen where they live due to other redeeming factors.

Thank you also for your hard work on the rezoning project.

Sincerely,
Chris Kennel"

Lots of good common sense from Chris.

Note: As Douglas Farr and myself have been advocating, the best place for your photovoltaic system is on a two story garage on the alley. Xcel energy is already trimming the trees back there to protect the power lines. The most likely source of shade will then be a pine tree to the south. Try to get an agreement with that neighbor to allow you to prune that tree as required. If he won't grant permission for free, offer some money for a solar easement. You'll eventually earn all that money back and more.

Your New Zero Energy Cost Home Must Be All Electric

2009-12-12T08:33:00.000-08:00

Xcel Energy currently charges $10.28/month just to hook you up to gas. That means if you do a great job of design and building, and drive your gas usage to zero, you still pay over $120/yr for the privilege of gas heat backup. You can install a huge PV or thermal solar system, but it won't eliminate that charge.

So the easiest way to get rid of it is to eliminate gas to the house.

For all you chefs out there who love to cook with gas, remember that it puts quite a bit of CO into your home. You may want to check out induction cooktops which reduce the chances of anyone burning themselves, and actually heat quicker and more energy efficiently than gas.

Solar Cats and Passive Solar Energy Collection

2009-12-04T12:58:00.000-08:00

Did you ever wonder what the surface temperature is of your solar kitty?

As you can see, Natasha runs about 112F on a clear, cold winter day in Denver. Note: she is laying in front of a window with an SHGC (solar heat gain coefficient)of 0.56. That's far higher than the average low E window which has an SHGC of about .32. What's that mean to a cat? About 15F. A black surface in front of a conventional low E window under the same conditions is around 97F. Still warm, but that's a significant penalty for not specifying the right windows.

Hurd "hard coat low E" windows from Rocky Mountain Solar Glass has been the only local solution I have found for passive solar. Serious Windows (formerly Alpen) should also be able to supply a high SHGC low E window. Most other window suppliers and manufacturers have no clue about this issue.

Increased solar gain in the summer isn't a concern, because these are south facing windows. In the summer, the sun is high in the sky, and the window is completely shaded by the properly designed overhangs. Even the Energy Star program is silent on this, although their energy modeling computer programs do give credit for high SHGC windows on the south side.

LED Lighting in 2009

2009-12-01T20:19:00.000-08:00

Here's a photo of the aforementioned lighting "hack".

It took 15 of the 1.5 watt LED bulbs to generate enough light for this kitchen remodel. Current cost: $4 each.
This configuration will use about eight times less electricity and save about $45 per year, including replacement costs. That's a 16 month payback.

Druid Zoning

2009-11-21T13:39:00.000-08:00

Denver's new zoning code is on track for approval in February, after about five years of hard work. In the last few days, many folks have rallied in support of "passive solar access". It's a big enough groundswell that it has gotten everyone's (except the Mayor's) attention for the moment.

At first blush, it sounds like a great idea, but only one person has attempted to quantify what it really would require in terms of zoning.

Bernadette Kelly of MOA describes "block sensitive height limits" as a solution. Similar to how the context sensitive front setback is calculated, it would regulate building heights based on the current status of what's on the ground. She cites an English "right to light" law that derives from the Druid civilization. To paraphrase: "if a structure has had access to the sun for at least 20 years, it is illegal to ever block the sun from that structure".

It does solve the problem, would satisfy most solar advocates, but it is a bit impractical to implement, and would greatly diminish your neighbor's current property rights. (Full disclosure: the author is a solar advocate, but hopes to profit from the ability to increase density in transit neighborhoods)

It's doubtful that this proposal will see the light of day in this version of the zoning code, but it's not without merit. Some neighborhoods of one story homes and large side setbacks may want to STAY neighborhoods of one story homes and large side setbacks, and there are no tools in Zoning Code draft 3 to help preserve that context. Two story homes have always been allowed everywhere in Denver, and CPD has thus far refused to change that.

The Rubber is Starting to Meet the Road for Smart Grid City

2009-11-07T15:05:00.000-08:00

The Smart Grid pilot project in Boulder is now well enough along for the peak period re-pricing to be released.

http://www.dailycamera.com/schoolchoice/ci_13732272

This article missed answering an obvious question:

If you own a PV system that contributes to the grid during peak periods, will Xcel credit you at the higher peak retail rate?

My guess is yes. It's only fair. But this issue should be openly addressed soon because it will make your PV system pay off much quicker

LED Lighting Update

2009-11-06T07:32:00.000-08:00

Yes, CFL's suck.

So, we've been waiting for bright, affordable LED lighting to become available. Sam's Club has recently introduced 1.5W LED bulbs for $5 each. I believe Xcel energy is subsidizing some of this cost based on a flyer displayed in the aisle. If anyone knows more about that, please post a comment.

Anyway, 1.5W is only producing about 78 lumens, which means you'll need roughly six times the number of bulbs more than "normal". This is a daunting problem that will keep most folks out of the LED replacement business until a market solution or even brighter bulbs are introduced.

In the meantime, we developed a hack using "Medusa" floorlamps, which can be found for as little as $20 and will convert a standard octagon ceiling box into a fixture with five medium base openings. An added bonus is that you can direct the lighting to where you need it.

Let's say you have rentals or are doing fix and flips. You already know that fluorescent lighting and CFL conversions do NOT add value, even though operational cost is lower. The light quality of LED's and even lower operational costs SHOULD add value to your project. Don't be cheap - the $20 marginal cost per fixture is only a couple hundred $ for a house.

Edit: photo posted above

Dual Flush Toilets Now Affordable

2009-11-02T12:06:00.000-08:00

If you've been too cheap (like me) to get a Toto or Caroma Dual Flush Toilet, now you have no more excuses. For a long time, these toilets have averaged $400, making them difficult to pay for themselves.

Sam's Club is stocking the Alexis HET (high efficiency toilet) 1.1 gpf liquid, 1.6 gpf solid dual flush toilet for $99.

Since Denver Water is giving a $125 rebate for them, this is a real no-brainer.

Go get one while they still have 'em.

Solar Shading Cont'd

2009-09-23T08:43:00.000-07:00

The classic all-aluminum rollup design is my personal favorite solution for exterior window shades. They're economical, ( $150-$300), self-storing, accessible from inside the home, and infinitely adjustable depending on the season or your whims.

They can be ordered at Home Depot or online at http://www.screen-house.com/awnings_rollup_aluminum.htm

Sun Control - One of the Solutions to Summertime Overheating

2009-09-16T08:27:00.000-07:00

This topic is old news for those of you with those big, west-facing-mountain-view windows. They create an inferno for you in the summer. You may have even spent thousands on beautiful floor to ceiling blinds to shut out the sun.

However, unless the shades are physically outside the window, they are relatively ineffective. Once the sunshine comes in the window, it stays inside as heat.

So the shades must be on the outside.

The easiest, quickest, and least expensive way to install an exterior window shade without completely ruining the view just might be from Screenmobile. They are a national franchise, and I've used the local branch often for conventional screen replacement, and found them to be a good solution for an annoying problem.

Heat Pump Hot Water Heater

2009-08-28T08:12:00.000-07:00

So, you're trying to decide how to heat the domestic hot water in the zero energy house you are designing for Denver.

Solar hot water heaters are an excellent choice. However, the logistics of a solar thermal installation are daunting compared to a typical appliance installation.

A logistically easier solution is to use a heat pump water heater (HPWH) in conjunction with PV solar.

Rheem has just released a new nice-looking unit.

The jury is still out as to which configuration will be best. Recent test results and common sense are beginning to favor HPWH with PV. The reasons for this are that solar DHW is insufficient and inefficient in the winter, and underutilized in the summer. A grid-tied PV system has the advantage of constant efficiency and 100% utilization year round. In addition, large PV cost reductions are coming, but none are expected in solar thermal. State-of-the-art solar thermal collectors still use supply-restricted copper, aluminum, and glass. The labor content of solar thermal installations is also quite high.

Some puzzles remain with the implementation of HPWH systems. Per the manufacturer's recommendations: "Because the heat pump’s exhaust air is cooler than the surrounding atmosphere, these water heaters generally do not belong in or near busy living areas of the home." Since they pull the heat out of the surrounding air, a small, airtight mechanical room isn't the best place for it either.

Discussion of HPWH locations:

1. The garage. A new, well insulated garage might work. An uninsulated garage slab gives off enough low temperature free geothermal heat* to prevent freezing of the pipes to the heater. There are at least two problems with the garage, however: 1. In summer, the HPWH gives off cold air that would be more desirable inside the living space than in the garage. Ducting air from the garage to the house is a CO hazard, and not recommended. 2. If the (insulated) garage door is inadvertently left open in the winter for an extended period, the water lines to the HPWH are at risk of freezing.

2. Mechanical room with forced ventilation. The control scheme and ducting layout for this ventilation can get complicated and costly.

3. Basement. This is where you usually find the water heater in new construction, and will work just fine if you don't mind a cold basement in the winter. If you finish the basement and add heat to it, that heating system will be feeding the HPWH the heat it needs, and this will spoil the overall efficiency of your system.

"The House as a System" philosophy of home design will get a real workout on this one. Please enter a comment if you've heard of any other solutions.

*A perimeter insulated slab in an insulated garage gives off 5-15 Btu/hr/ft2, based on preliminary research. This is a great match for a 7000 btuh HPWH.

The Greenest Building is Usually the One Already Built, but Not Always

2009-08-18T02:00:00.000-07:00

I'm really not trying to anger preservationists or tree-huggers here, I'm just analyzing a trite slogan from an engineering perspective. I'm a pragmatic preservationist.

The question is whether or not you should rehab and do a green retrofit on an existing building or replace it with a well-designed low energy new building. The correct answer can only be found after making some reasonable assumptions, cost estimates, and estimates of resale value.

You don't "waste btu's" when you tear down an old building. Those btu's were spent when the building was originally built, and there's nothing you can do to get 'em back.

You can only choose not to spend new btu's on a new building.

And btu's are just another form of dollars.

So it's always an economic problem, eg., what's the present value of retrofitting the old building vs. building an entirely new one. This analysis must be done for every building using each case's unique problems and assumptions.

In residential at least, it's fairly easy to build a new "zero energy" replacement house, but fairly hard to retrofit an old house to zero energy. The cost of the new house can be estimated pretty accurately, but trying to estimate the retrofit cost of the old house is risky. Every old building is different.

The embodied energy of the new building is just part of the down payment on a really good investment. The value of that energy is in the cost of construction. The landfill space required for the old building is also given a dollar value in the cost of demolition. The embodied energy of the old building is a "sunk cost" and doesn't factor in the analysis.

The main thing that doesn't have a dollar value in this analysis is the generation of CO2. Lawmakers have begun trying to put a dollar value on that. Eventually this "carbon tax" will be pretty accurate, and will favor the old building.

Most estimates put the embodied energy of a new building at 5-15% of the lifetime energy usage of the building. That means the operating energy usage of the building is about ten times more important than the original energy content.

Therefore, it may be a catchy phrase, but it's very unscientific to generalize: "The Greenest Building is the One Already Built". Be sure to say "usually".

Mini-Splits or PTACS are the Key to Net Zero Energy Homes

2009-08-13T06:07:00.000-07:00

High SEER minisplit heat pumps have finally caught the attention of high efficiency homebuilders. Postgreen, a redeveloper in Philadelphia, touts "geothermal efficiency at a fraction of the cost": http://www.postgreenhomes.com/models/

When you add PV solar to a house and a high efficiency and lo-temp-capable heat pump, then you really don't need to pipe natural gas to the home. (Cooking meals with gas may be preferred by chefs, but it is neither healthy nor energy efficient. Gas ranges put out a lot of CO). That saves the $12/month gas hookup fee.

Besides, you can't send natural gas back to the utility like PV solar does. In superinsulated homes, this scenario also makes solar thermal obsolete for heating and domestic hot water (DHW)

Why? Because even at a solar conversion efficiency of only 10%, in the summer, you are putting energy back on the grid and dollars in your pocket Every. Single. Day. Thus, the yearly system efficiency and ROI is better than solar thermal.

It's becoming accepted worldwide that the only way to acheive true net zero energy is with an all-electric house and PV. Minisplits are part of the puzzle.

A few more of benefits of these heat pumps:

1. Less floor space used inside the house for mechanicals.

2. Compression-cycle air conditioning included "for free".

3. Better zoning is possible than with any sort of central forced air system.

4. In smaller homes, the installed cost is a fraction of a centrally ducted system.

Denver's New Zoning Map is Dropping the Ball on Sustainability

2009-07-19T14:21:00.000-07:00

Soon after being named in the top ten cities for sustainability , Denver may damage it's standing because the proposed new zoning code is largely ignoring the benefits of detached accessory dwelling units (dADU's).

First, a little history:

The zoning code rewrite was called for as far back as 1989. Mayor Hickenlooper hired Peter Park to shepherd it in 2004. Meanwhile, preservationists like Jim Lindberg were concerned how the old code was allowing redevelopers to potentially ruin our historic neighborhoods. Blueprint Denver was begun in about 1998 and released in 2002 as the guide for a new code. The Zoning Code Task Force (ZCTF) was appointed in early 2005, consultants were hired, problems identified, and neighborhood contexts were defined.

Along about early 2008, third parties realized that sustainability issues had been heretofore largely ignored by city staff and their consultants. Michael Henry and Don Tressler of INC (InterNeighborhood Cooperation, an RNO), are the most significant of these third parties. Although Greenprint Denver was initiated in 2006 and widely admired, it was two years before Greenprint representatives were spotted at any ZCTF or Blueprint meetings.

At the request of INC, Park then hired Doug Farr to recommend sustainability strategies for the new code. The author wonders why a Chicago based consultant, however well qualified, could be a better choice than a local firm. For example, does Farr know why evaporative coolers are such a great peak power solution for the Denver area? Probably not. It turns out that swamp coolers ARE a zoning issue. No matter, he wrote the book, and made an effort to interview local experts like Michael Tavel.

Also, in the spring of 2007, Bob Sperling and James Van Hemert organized the Friends of Granny Flats after they realized that the Zoning Code Task Force was almost unaware of the existence and popularity of thousands of historic carriage houses in Denver. They gave a presentation to city staff in April 2007 that was well-received and put dADU's on the radar.

Farr gave his report to the ZCTF in September 2008. At that meeting he was asked, "what are the biggest things we can do in Denver?" His reply, "Two things: Share cars and Solar Access". It looks like the private sector is already targeting the former. By solar access, he went on to explain, on north-south Denver streets it means allowing a taller garage with solar panels on the roof, with laws to prevent future shading of it. After the meeting, he took the concept further and proposed, "for sustainability reasons, the code should require the installation of an accessory dwelling unit whenever these alley structures are built."

(Coincidentally, at the same meeting, the housing affordability consultant, Don Elliot, was asked the same question. His reply, "ADU's, reduction of the minimum buildable lot size, and inclusionary zoning." The ZCTF took the first two choices to heart and they are well-represented in the draft code. The affordability recommendations promised ADU's "in a wide range of districts." The efficacy of Denver's current inclusionary zoning law is unclear.)

After staff parsed Farr's report, they issued the Jan. 14, 2009 sustainability memo , and ADU's are prominent. Mention is made of future study of things like solar fences, kind of a tough putt in urban neighborhoods with mature trees. More on that here and here.

Unfortunately, the proposed zoning map is disallowing ADU zoning over most of the city.

Review the Map . Look for suffixes like -B1, - C1 etc. For example, if your neighborhood has U-SU-C you don't get ADU's, but if you have U-SU-C1, you get 'em. B2 & C2 zoning allows them only on some corners, which is better than nothing, but there isn't any B2 and C2 on the map. Why develop a zoning typology and then shelve it? There are a lot more questions like that once you study the map. Please do, and weigh in .

So, in 2009, after all this work, why is the city offering up ADU zoning in less than 5% of the city?

Edit: As of late August 2009, the areas with ADU zoning shown have increased, but they are still insignificant. There is a small amount of A2, B2 and C2 now shown.
Edit(2) As of November 2009, there is tons of ADU zoning shown. Meanwhile, "Friends of Granny Flats" recommended ADU zoning for ALL single family districts.

Solar Access for Denver Neighborhoods

2009-04-14T14:47:00.000-07:00

The Denver Zoning Code has been rewritten, and is on the verge of release for public comment. The issue of Solar Access has been put on hold for at least a few months. This is understandable, as the release of a large, important document like this is very difficult.

Unfortunately, solar systems are being built in Denver with no protections against shading from neighbors.

For more, please see read this document:

Solar Access for Denver Neighborhoods

Connecting the Dots Between Google and the Smart Grid

2009-03-27T02:20:00.000-07:00

How the Google Math Adds Up:

1. Google is rapidly becoming the nation's largest single consumer of electrical energy.

2. 2007: Google announces their goal of producing renewable (solar) electricity as cheap as coal. The goal: $ 0.025/kwh

3. Plentiful solar electricity is generated during the common peak demand periods, hot summer afternoons.

4. 2009: Google announces the PowerMeter to help implement the "smart grid" as they envision it. A properly implemented smart grid could increase the selling price of peak demand power to $ 0.25/kwh or more.

Therefore, #4 causes a 3x to 10x increase in the profits of #2, while #3 + #2 solves problem #1.

The Return of the Carriage House, Denver 2009

2009-03-27T00:20:00.000-07:00

Detached accessory dwelling units will apparently be allowed in Denver's new zoning code. The sustainability benefits are so numerous that ADU's tend to be the darling of city planning staffs nationwide.

The following article was written by Becky Alexis, a Platt Park architect involved in sensitive redevelopment.

"The carriage house has been a part of our built environment since the beginning of the twentieth century. Found everywhere in our community from Country Club homes to low income areas, the accessory dwelling unit has historically provided home owners needed flexibility for guests, expanded family, boarding and household help. Today our need for a sustainable housing sector is eased if home owners have the same opportunity. By converting the rear zone of a property into the highest and best use, families, neighborhoods and municipalities benefit socially, economically and environmentally.

Giving home owners the opportunity to add functional value to their property helps all socio-economic levels. From the first time home buyer to the elderly, the added dwelling space helps all owner-occupants to stay in their home. Fabrication is less costly than conventional housing and uses include family living, child and elderly caregivers, workspace and rental income. This flexible space affords opportunity for families’ changing needs in a time where the risk of home loss is high. As a work space, the detached dwelling reduces costly commuting requirements. The building form adds security and beautification to the alley and creates intimate and properly scaled courtyards which require less water and maintenance needs. Simply, the carriage house aids in preserving single family living.

Keeping families in their home is critical for the stability of neighborhoods. Less housing turn-over means less speculator driven scrape-offs, and a preservation of the neighborhood character. The added benefit of a carriage house to a property increases the value of other homes in the area. The added activity also reduces crime, especially in the most vulnerable space, the alley. Conceived as 800-1200 s.f. apartments over a 2-3 bay garage, these units reduce existing and future off-street parking demand. Safety, secured property values, and an improved built environment make the neighborhood more livable and desirable for existing and new residents.

To the municipality, this non-obtrusive densification of our neighborhoods has numerous benefits. The existing utility infrastructure is currently under utilized, so adding more dwellings would be accommodated and would add a larger tax base to support the existing infrastructure. Families would not be financially forced into the suburbs. Children could stay at their schools. Commuting by vehicle would be minimized, and our local public transportation would be better utilized. Jobs would be created by the people that build these structures and by the folks that choose to work out of them. It is a win-win situation that reduces stress on families, reduces falling house prices, minimizes scrape-offs which fill our landfills, reduces water needs with more sensible backyards, and reduces our carbon footprint.
Denver’s own Peter Park, the City Planning Manager, has said, “When cities stop changing, they start dying.” This is a “Shovel-ready” opportunity for good design and correct context to fulfill real and perceived needs."

-Becky Alexis, HIVE Architecture, LLC

Polymer ISC Solar Collector Debuts

2009-02-26T20:20:00.000-08:00

Just a few days after my post about passive solar thermal water heating, the grandson of the Arthur D. Little collector design came to my attention. Called the Solar Cache by Harpiris Energy, it has been designed only for non-freezing climates. With PEX pipe, which may be considered freeze tolerant, this will be a great product for economy installations, costing far less than the usual $6k solar DHW systems for freezing climates.

I just hope it doesn't get installed in colder climates, freeze, burst and give the product a bad name. When drain-down systems were used in Denver in the 80's, many an attic was flooded because of Murphy's Law. Even though there were freeze protection controls and backup freeze protection controls, they still failed.

Ironically, a common complaint from solar DHW system owners may cause pumps to appear in these passive systems. See, most systems have a solar preheat tank (with the Sun Cache the solar tank is on the roof), and a backup (fossil fuel) tank piped downstream in series. If the homeowner doesn't consume any hot water (like all day when he's at work) then the backup tank fires to make up for standyby losses, even though the preheat tank may be 140F or higher. In the summer, a solar system should be providing 100% of the hot water load on sunny days, so some homeowners get peeved when their gas bill isn't zero and the backup tank is coming on every hour or so. A really tiny recirculating pump with a simple control is a way to prevent the problem, but now you've added a pump to an otherwise elegantly simple system. The other beef with the "uninsulated" storage tank on the roof is that you'll never have any solar hot water left for the morning shower, the storage water will drop close to outdoor ambient by morning.

Rheem has also come out with a passive collector with some freeze tolerance. The collector loop is charged with antifreeze. Again, great care should be used on the supply pipe, even in "non-freezing" climates.

Hail Resistive Roof Saves on Insurance

2009-02-08T08:07:00.000-08:00

State Farm just started putting this line on my insurance declaration page:

Premium Reduction:
Hail Resistive Roof: $521/yr.

My roof is a spanish tile look-alike made of stone coated steel from Gerard

I don't know if clay-based or concrete tile roofing qualifies for the discount, which is about 30%. Both of those systems, however, require a significantly stronger roof structure due to the higher dead load. (edited 2/10)

So, I got a premium-looking roof that pays for itself in ten years compared to asphalt shingles.

It's a very green choice because the steel is recyclable, and guaranteed for 50 years.

Green Roofs?

2009-02-06T10:50:00.000-08:00

I have remained on the sidelines with regard to promoting green roofs. I'm hesitant partly because many people in the multifamily industry have this saying that goes "flat roofs always leak".

In my own experience, the most frequent and worst leaks occur at the low spots where ponding occurs. A pond on your roof causes dust in the air to stick to the surface of the water. Over time, this dust builds up and starts looking like dirt, or soil. Seeds get blown into this muck, and sprout. I know this is a poorly designed ad-hoc green roof, but the fact remains that leaks never start in the dry spots on flat roofs.

I guess some sort of roof garden would be nice if you also had a roof deck and actually used it.

I'll let Dr. Joe L., every building scientist's hero, explain it:

"Green roofs? Grass and dirt are not energy efficient.Work with me here. Which saves more energy—2 inches of dirt or 2 inches of insulation? Which saves more energy—grass or a white colored membrane? Which is more expensive and does not save energy—grass and dirt or insulation and a white colored membrane? Which needs to be watered to keep the grass from dying and blowing away? But they are beautiful and look cool. And that apparently is more important than cost and energy savings. Okay, I can live with the beautiful and looking cool argument if that is in fact the argument—but don’t clutter it with half-truths such as heat island effects and water run-off. There are other (better) ways to deal with each."

He goes on to admit he won't win the argument, so he provides the proper drawing detail that works.

In semi-arid Denver, I'll posit that the money spent for the water needed to keep your roof alive will be far more than the dollar value of any perceived benefit.

Passive Solar DHW

2009-02-05T05:52:00.000-08:00

To some, the holy grail of solar thermal is a system without pumps and controls.

Himin of China manufactures a nice one:

At Solaron in the '80's, we purchased the manufacturing rights to a passive DHW design developed by Arthur D. Little. The problem was that the pipes going to the collector would freeze in the winter. Frozen pipes in the attic were so undesirable and difficult to eliminate that we ultimately abandoned the whole project. As far as I know, no one is pursuing this type of design in northern climates.

Now that building codes are beginning to actually recommend insulated roof planes and conditioned attics, the Chinese design looks very interesting. The pipes in the attic won't freeze because the attic is inside the house envelope. As long as the piping to the roof-mounted tank is kept extremely short, it won't freeze either. Natural convection within the pipe and heat conduction along the pipe from the tank and the attic area would prevent freezing.

Note that the water in the evacuated tubes probably won't freeze. Every day they warm up a bit even if the day is completely overcast. This insolation should be enough to prevent freezing even under the worst conditions in Denver.

From Arthur D. Little, we also learned that the roof-mounted tank will never approach freezing temperatures anywhere in the continental US. (Basically there's enough solar insolation even on completely cloudy days to keep the tank above 40 degrees)

The main attraction of this design is that system efficiencies are far superior to pumped designs. Also, with no moving parts to fail, the life-cycle cost is held low, and the ROI is maximized.

Edit, corrections 1/10/11 (the tubes contain water, not heat pipes.)

It's Not Price-Pfister, but the "P" is Silent

2009-01-23T23:46:00.000-08:00

In a recent trip to the Wellington Webb building, a had a chance to use my first waterless urinal. I don't yet know how they work, but it was totally odorless and splashless, all in all very pleasant.

If your household has at least two guys, you should install one. The water savings will eventually pay for it.

Update: About six months after installation, I visited the restroom in the City and County Building, and one of these urinals was malfunctioning somehow. It was NASTY. Caveat Emptor, and train your maintenance staff!

Domestic Hot Water for Zero Energy Homes

2008-12-15T09:22:00.000-08:00

Zero energy homes (ZEH's) in the near future will be simple, all electric, and supplemented with PV.

Hybrid PV/thermal solar collectors may be the best solution as costs come down. Sun Drum Solar is now offering a product. Dawn Solar also offers a building integrated hybrid PV roofing system. PVTSolar uses an air-based approach. When I worked at Solaron in the 80's, we abandoned air-based systems, and we were the world leader in air-based until that point. These are the only entries so far in the hybrid market sector. I expect to see more manufacturers enter the fray soon.

Whether or not a solar thermal DHW system is used, a grid-sourced backup water heater is required.
An affordable heat pump hot water heater (HPWH) is now on the market:
https://airgenerate.3dcartstores.com/index.html

This type of system uses only 25%-35% as much electricity as a standard resistance water heater, making it the best choice for a ZEH without solar thermal.
Another bonus of these heat pumps is that they can supply "free" summer cooling for the house.

In the near future as costs stabilize, we'll learn if this $700 is worth it for a home with solar thermal or hybrid collectors. In Denver, a home with 100-150 ft2 of solar thermal or hybrid collectors probably won't need it. The $700 marginal cost would take too long to recoup because the solar is providing 90%+ of the domestic hot water load.

More on Advanced Wall Systems

2008-12-03T11:48:00.000-08:00

Joe Lstiburek was at the EnergyStar Summit this week, and was ranting about the wall system we should be using in this climate. Bottom line - for less money than than the historical R-13 2x4 wall system, you can build a styrofoam sheathed R30 2x6 wall. Truly a no brainer.

However, there are two significant barriers to implementation:

1. Your framers, who have such a difficult time coping with wall systems that use LESS wood.

2. Your structural engineer, who wants OSB sheathing used everywhere.

One slight potential problem within the assembly, vapor condensation on the inside surface of the styrofoam, has been bothering me for a few years. Joe explained that this has been addressed in IRC 2009 with a climate zone prescriptive solution. It specifies the minimum R value for the external insulation to avoid condensation. This value is also a function of the stud cavity R value, but Building Science Corp. typically recommends 1.5 inches of taped external foam.

What Ever Happened to Off-Peak Electric Rates?

2008-10-30T07:01:00.000-07:00

In the 1970's, PSCO introduced off peak electric rates, which were designed to flatten their demand profile. At the time, a kwh used between 10pm and 6am was priced at less than a third of the cost of an on-peak kwh. If utilities can just tweak their customers usage habits thru rate schedules, they can really drop their capital costs. That is, they won't have to build that new power plant just to cover three week long spikes in demand.

Over the years, the PUC added many "cost adjustments" to the electric bill, which watered down the off-peak savings to be had. Eventually, all customers lost interest in the whole program and it was cancelled. These cost adjustments are multiplied by the kwh usage, and now account for around 66% of a residential electric bill. It didn't matter if all the usage was off-peak, these adjustments were still there in full. So, in 1980 if you were saving 2/3 of your bill with off-peak rates, by 2008, your savings would be 2/3 of the remaining 34%, or only 22%.

Finally a Foolproof Toilet Fill Valve to Save Water

2008-10-12T17:32:00.000-07:00

We had three brand-new toilets that leaked slightly, apparently through the flapper. Even if it wasn't a significant amount of water, or caused a noticeable increase in the water bill, it caused an unsightly red mold to grow. Even though the toilets are cleaned weekly, the mold can be seen as vertical stripes in the bowl wherever the leak runs down the sides of the bowl.

Anyway, Fluidmaster now makes a new fill valve that refuses to refill if there is a slow leak. As soon as the handle is jiggled, however, it will refill. So a tenant can use it just fine with minimal inconvenience, but the normally wasted water is saved.

This may increase your callbacks in new single family construction, but it's the perfect solution for buildings with maintenance staff.

H4H Redefined the State of the Art for Zero Energy Homebuilding

2008-10-07T02:32:00.000-07:00

With NREL, Habitat for Humanity has built and tested the simplest Zero Energy home that I've seen to date. Lots to learn from the following final technical report:

http://www.nrel.gov/docs/fy08osti/43188.pdf

Perhaps the most surprising lesson is the poor overall system efficiency of the solar thermal DHW preheat system. It shows that these systems may be hardly worth the effort. Ongoing maintenance for a system like this will further degrade the cost/benefit ratio for this subsystem.

NREL Denver Tour of Solar Homes

2008-10-06T00:47:00.000-07:00

On Saturday, our East Wash Park home was on this year's Denver Tour of Solar Homes , sponsored by NREL.
Here's the blurb from the tour book:

Dickson Residence

This large house (4200 square feet) was completed in 2004 and is an updated version of the “Denver Square” design. The parcel was formerly a public service substation on three lots. The house uses a true direct gain passive solar design in that it has south facing glass and mass (concrete floors). Please note that the passive solar heating provides 90% of the space heating requirements – so much so that the radiant floor back up system is rarely used. If the owners were to do this again, they would install a less expensive backup system. In some places the concrete has been stained so that it is the actual floor. In other places, cork is laid over the concrete.

The house is joined to the building next door, which originally contained battery storage for the Denver Tramway system. Now the building houses an office and shop area.

The house is built using SIPs (structural insulated panels). In getting the permits for the house, the Denver plan review and inspection departments added eight months of delay in getting a building permit, according to the owner, because of their inexperience with SIPS. Greenprint Denver may be helping to alleviate the problems like this.

An interesting note is that three of the stained glass windows in the house were designed by a relative of Frank Lloyd Wright.

Passive Solar Features

Sunroom/mudroom

Mass of 2” of concrete on the floor

Trees planted on the east and west for shade control

Photovoltaic Panels

3.3 kW system

Grid tied

Utility bill has decreased $55 per month since installation

Thermal Envelope / Thermal Comfort

Insulated above code with SIPS

Low-e windows

Interior and exterior shades

Evaporative cooling (unique indoor cooler)

Expanding foam insulation around windows and outlets

Zoned heating

Night setback thermostats

Radiant floor backup heating system

Lighting

Some CFL lights

Motion sensors or timers in the mudroom and garage

Construction

6” thick SIPS walls

Thermal breaks at entry doors and perimeter of entire foundation

Pre-plumbed for solar thermal collectors

Lightweight Metal shingles

Appliances

Energy Star rated

Sealed combustion boiler/hot water heater

Transportation / Lifestyles

Hybrid SUV

50% of all errands are done by bicycle

Light rail is used once a week

Recycling

Composting

Vegetable gardening

Re-Use / Salvaged Materials / Recycle

Reclaimed brick

Reused existing building and converted into a home office from its original purpose

Unique Features

Homeowner trained in solar during the energy crisis of the 70’s

Homeowner holds patents for pneumatic fittings, valves, and a nose hair trimmer

Green Features

EPS insulation

Stained concrete floors

Reused an entire building and converted into a home office

No particle board was used

Steel roof

Cork floor

Water Features

Low flush toilets (5 out of 5)

Low flow shower heads (3 out of 3)

Xeriscaping

Drip irrigation

REC’s and Windsource

On demand hot water system: “Doorbells” in each bath summon hot water without wasting it

A little bit of nice publicity from the WPP....

2008-10-05T23:35:00.000-07:00

http://kevintesting.googlegroups.com/web/WPPKTD.pdf?gda=0Va3kDwAAAAnKIMncx6ukRKQXuLFP__Do_CwWda2FNSImGT2MKwxy2HpCSjbUfPiF0VurU3U4gL9Wm-ajmzVoAFUlE7c_fAt

My First Electric Vehicle

2008-09-28T08:06:00.000-07:00

Prices for low end Electric Bikes recently came down another notch, so I snapped one up.
It's fun, and really solves the problem of getting too hot when bicycling around town. You can let the electric motor do all the work on the way to a meeting, and arrive relatively fresh. It has pedals and a seven speed derailleur, so there is always the opportunity for exercise. The small 15-mile range has never been an issue, most bike trips are shorter than that. However, for $100, you can add a second battery to double the range, or to quick-swap batteries like a cordless drill.

GM Will Provide Electric Cars Soon or Die

2008-08-13T16:05:00.000-07:00

OK, you gotta keep your old clunker running 2-3 more years until the GM Volt is released.

Current estimates have the Volt going about 40 miles before a little gas engine kicks in to increase range. Five more years of battery development will increase range enough to wean us from gas entirely.

As we all have hoped, technology will get us out of this mess, and please note that the free market economy is what encourages innovations. Government incentive programs should be used sparingly. Case in point, the laws that encouraged ethanol production have affected food prices. It's hard to predict unintended consequences, and the free market is smarter than any of us.

Start Learning about V2G (vehicle to grid)

2008-08-13T07:00:00.000-07:00

The oil needed for transportation is probably the nation's #1 issue right now. The solution is now being fleshed out, and it's simple, elegant and involves your home.

I'll give the executive summary:

1. Forget Hydrogen powered cars.
2. Forget Natural gas powered cars.
3. Forget ethanol powered cars.

Daily driving trips will be done with an electric car that plugs into the grid at home, work or anywhere. Today's grid can already handle this growing demand, but it must become a smarter grid. Digital powerline signals will meter your electricity usage wherever you plug in. The V2G part comes into play during those demand peaks. All the electric cars that are plugged in during those times will be called upon to put electricity back on the grid, thereby avoiding any potential brownouts.

The reason electricity wins is because it is TEN TIMES cheaper than gas per mile driven. Wind electricity is already cheaper than coal, PV electricity promises to be even cheaper than that.

To learn more, google "V2G" The links change daily.

Of course the solution for the long-distance freight industry has been obvious for 150 years. Trains will replace trucks, a perfect reversal of the 20th century. Electric trucks will be developed to distribute the freight on a local basis.

Obvious Need for Smart Metering

2008-05-30T09:51:00.000-07:00

Some sort of weird incentive program has been approved by the PUC. From the Denver Post article:

"Under a new incentive plan approved by the commission, Xcel could recover from ratepayers all costs for programs that encourage customers to use energy more efficiently. Xcel also could receive bonuses if it meets certain targets." Is it just me, but isn't this some kind of circular logic? Here's another way to say it, and it's hard to believe the Post can write this with a straight face: "Xcel will recover from ratepayers all costs for programs that encourage ratepayers to use less." Auugghhh!

How about a rate-based incentive program? That's how the rest of our economy works. You are charged the cost of a service plus a profit. The amount of profit is determined by the market price.

Since Xcel is a monopoly, the market price is set by the PUC. Therefore the market price should be the cost plus the 10% profit that Xcel is allowed by law.

The problem is that the rate structure doesn't reflect actual costs.

The smart metering initiative will solve this problem, so incentive programs like this are unnecessary because normal economic laws of the marketplace will naturally encourage conservation and alternative energy.

Home Tour a Huge Success

2008-05-16T07:40:00.000-07:00

The turnout for the Wash Park Home Tour was the biggest ever. We weren't allowed to stay around during the tour, so if anyone has further questions about the home, feel free to call Kevin at 720 435-5909

Solar Home on the Wash Park Home Tour

2008-04-27T20:04:00.000-07:00

Our personal residence, a "solar Denver Square", built in 2004, is on this year's East Wash Park Home Tour.

This annual event is the biggest fundraiser for Steele Elementary.

Things to look for:
1. High SGHC glass used on the south side.
2. "Poor man's terrazo" diamond-ground and stained concrete floors for thermal mass.
3. Rare indoor swamp cooler that serves as a humidifier in the winter.
4. Infloor radiant heat.
5. On demand hot water.
6. Near-zero exterior maintenance.
7. Low-water landscaping.

MORE DETAILS:

DICKSON RESIDENCE

“The Substation House”

1491 S GAYLORD

2003-2004

Green Features

Site is at the south end of the block which allowed unrestricted access to the sun. (little to no shading)

Passive Solar : Large window area on the south walls of the house. The interior temperature swings somewhat because of the heat gain from the sun. After a sunny day the living room temperature will be 68, and early in the morning, it will be 64. A room temperature of 65 feels quite comfortable because the house isn’t drafty and the walls and windows are relatively warm compared to older homes.

Minimized window area on east, north, and west. On the north, to save heat in winter, on the E & W to reduce heat gain in summer and shoulder seasons. Most of the E & W windows are shaded for the same reason.

South window glazing is a special low-e coating with a high solar heat gain coefficient (SHGC) to maximize heat gain in winter. This keeps the space heating cost to $20/month for the main house in the 4 coldest months.

Stained concrete floors provide thermal mass to “save up” daytime heat until nighttime. This process is unregulated and occurs naturally and automatically. 2” thick concrete was poured on the first and second floors. The basement slab is 6” to prevent cracking due to somewhat expansive soil. Similarly, the concrete floors help keep the house cool on hot summer afternoons

Large window well on the south side provides more heat and light than usually found in a basement.

Structural Insulated Panels (SIPs) used for wall and roof construction. SIPs can be described as stressed-skin foam panels. They provide a high R-value and ensure a tight heated envelope (reduced unwanted air leakage). Having a SIP roof and no conventional attic trusses make the attic livable space for very low cost.

Unique indoor-mounted evaporative cooler uses 5 times less energy than A/C for summertime cooling. The airflow is reversed thru the cooler in winter, using the HEPA air filter, thereby serving as the humidifier. The indoor location of the evaporative cooler allows easier maintenance. Denver is one of the best places on the continent for evaporative cooling.

Medium-high efficiency boiler for the in-floor radiant back-up heat and domestic hot water. The boiler is “direct vent” to eliminate the possibility of CO entering the house. The combustion air is sucked in directly from the outside, and blown outside after combustion. The radiant in-floor heat system was installed by Advanced Hydronics. Because the home uses such little backup space heat, this boiler was the best choice at the time.

3.3 KW photovoltaic system mounted on the garage roof feeds power back on to the grid when it is generating more electricity than the home is using.

The pre-existing red brick building was saved and re-purposed as the home office/shop. (It still has poor energy performance, but a brick insulation retrofit experiment is ongoing. This is a city-wide problem needing a solution ASAP.) Side note: this building was originally built in the late 40’s to store a huge bank of lead-acid batteries. These batteries were part of the electrical grid for the Denver Tramway system.

The SIP construction allowed the easy finishing of the attic space, providing a very useful 3^rd floor bonus room. (Conventionally built homes have vented attics, which are hot in summer, and cold in winter, and the single largest cause of heat loss and heat gain.) Design flaw #1: Kevin’s experience with finished attics led him to believe that the 3^rd floor wouldn’t need any heat. The assumption was that the heat from below would migrate up. It turned out that the house is comfortable at only 65F, so very little heat migrates up at that low of a temperature, and the third floor needs some heat at times.

Exterior below grade basement/foundation insulation. This is a really important detail that is rarely done correctly in new construction. The result is the basement zone stays at 64 degrees in the winter without any heat from the boiler.

No wood or gas fireplaces. Although we like the ambiance of fireplaces, any room with a fireplace would overheat quickly in this house.

Hot water “D’mand” pump. In each bathroom, the doorbell button summons hot water to the fixtures by turning on a pump for a few seconds. This is much quicker than turning on the faucet or shower and waiting for hot water to reach it. This also saves lots of water. This type of demand system is considered superior to timed recirculation systems that waste heat when hot water isn’t called for in the bathrooms.

Note on “passive solar cooling”: In the summer, the large double doors on the third floor can be opened at night along with the basement windows. Although over 1000 cubic feet per minute of air then naturally flows up through the house, it’s still not enough cooling effect for the two hottest months of summer. Denver’s climate has changed enough to generally require active cooling.

Low maintenance items:

a. Brick and stucco exterior.

b. 75 year stone coated steel shingles. They are much lighter and more hailproof than solid roof tiles.

c. Minimal painted exterior wood surfaces

d. Concrete floors have no maintenance, only cleaning.

e. Minimal roof penetrations mean fewer future roof leaks, and less air leakage. There is no fake chimney that is still put on most new homes. The joint between a chimney and the roof is the single largest source of roof leaks.

f. Low maintenance landscaping, wood mulch for weed control

18. Low Water Landscaping: Although there is a bluegrass play area, the rest of this large lot uses xeriscaping and a drip system for irrigation. Summertime water usage is usually under 10,000 gallons per month.

Smart Metering Coming to Boulder

2008-03-13T22:12:00.000-07:00

In previous posts, I have emphasized the need for "smart meters". In a move that was secret until today, Xcel Energy has announced plans for an even more ambitious program called the "smart grid".

They have chosen Boulder for the pilot program.

Cheap Photovoltaics Mean Easy Zero Energy Homes

2008-03-01T10:56:00.000-08:00

Let's see, there are at least two photovoltaic manufacturers in Colorado that promise $1.00/watt thin film PV panels "soon". If you add maybe $4.00/watt for installation, and subtract the rebates, which are at least $4.50/watt, it means your PV investment will be almost free, and it wipes out your electricity bill of $50-$150/month.

By any measure, this is a good investment. Think about it for a minute, and you'll conclude that your new zero energy home should be ALL ELECTRIC. It goes against today's conventional wisdom, but things are changing fast. The reason is simply that there is currently no method for a residential building to make natural gas and put it "back on the grid". In the summer, you'll have excess electricity production, but Xcel pays you retail for it. You can't do that with solar thermal either.

It can also be shown that Zero Energy homes with no solar thermal or natural gas appliances are simpler and cheaper to construct, so it's win-win all around.

Green Politics in Denver

2008-02-04T01:37:00.000-08:00

I'm personally not a big fan of traditional green politics, like passing laws that favor evaporative coolers over conventional A/C. (This happened in Denver recently) In most cases, market forces combined with lots of consumer education will produce the best results. "Unintended consequences" often result from poorly thought out laws (just ask Jared Polis). All other things being equal, fewer laws are better than more laws for many reasons. High on that list of reasons is the need for fewer lawyers.

Chris Nevitt, Denver's "greenest" city councilman, however, informed me of an interesting law passed by the city of Berkeley, CA. If you own a home and want to put photovoltaic solar on the roof, find a contractor and get a bid. The city will pay for it, then add the cost to your property tax bill to be paid over time.

With a financing scheme like that, there really aren't any barriers to PV ownership. The yearly savings on your electricity bill is instantly larger than the property tax increase.

PassivHaus Report

2008-01-12T11:42:00.000-08:00

This report, from the CEPHEUS project, should change your mind about many aspects of homebuilding.

I'll try to boil down the most important points in the report in regard to green building in Denver and Colorado:

1. If the walls are superinsulated, if excellent windows are used, and air infiltration is minimized, there may be no need for a heating system per se.

2. A house this tight does need ventilation, and a good way to precondition this air is through a buried tube. The common fear of mold in this tube shouldn't be a problem in Colorado.

3. An 80% effective air to air heat exchanger should be employed to recoup the heat from the stale air being exhausted from the house.

4. Eliminating the thermal bridging commonly seen in stud walls is highly important.

5. A superinsulated home automatically means a very uniform temperature distribution, and increased comfort.

Save Energy Washing and Drying Clothes

2007-12-02T14:45:00.000-08:00

Here's some reviews of Coldwater Tide . Theoretically, with this stuff you never need to wash with hot water.

Here's a product that can pay for itself in under a year, and also save a lot of time: spin dryer. It's probably a bit too soon for universal acceptance, but the simplicity of it makes me think the price will come down even further as sales go up.

Using Radiant Floors for Backup Heat

2007-10-18T22:02:00.000-07:00

Radiant floor heat is considered by many to be the most comfortable method of delivering heat. Even zero energy homes need a source of backup heating. Therefore, radiant is often the choice in high end custom homes, when cost is trumped by comfort and "sizzle".

After building and living in a near zero energy home now for three years, we have learned that radiant heat is quite comfortable when it is on. The trouble is, the solar and superinsulation aspects of the house prevent it from coming on very often. In fact, it hasn't been worth the extra cost of the system (about $10k more than a forced air system), and we wouldn't do it again.

Additional challenges with radiant floor heat:

1. A completely separate ducted system is required for summer air conditioning. A swamp cooler in Denver is by far the best choice (it typically won't use ductwork).

2. In order to filter, humidify, and ventilate, a separate ducted system must be installed. (Now add $5k to the above $10k).

3. The heating system is at risk of freezing in extreme conditions with a power failure.

More lessons learned in a superinsulated home:

The third floor attic bonus room has no heating source, and this turned out to be a mistake. It was designed without heat because in my experience, third floor attic rooms were always the warmest place in the house. It turns out this is only true if the heating system is running a lot. In our house, since the boiler is rarely on, the third floor doesn't get enough heat from naturally rising warm air. The third floor, therefore, stays about 4 degrees cooler than the main floor.

Close attention was paid to the basement insulation details. As a result, the heat loss is so low that the basement zone comes on only about 4 times per heating season. Again, that zone wasn't worth the cost when a couple $30 baseboard heaters could do the job.

Chicago's Demand Management Scheme

2007-09-28T22:13:00.000-07:00

I harp about utility demand management a lot. Take a look at what Chicago is doing in this field. With a properly designed system in Chicago, you might never have to pay more than $0.03/kwh. In Denver, you never can get a rate of less than about $0.08.

Technically, it doesn't save any energy or prevent CO2 generation. It does, however, eliminate the necessity of building of new, larger power plants. Reducing utility capital expenditures should help keep electric costs down.

In fact, it's the first on the list of sustainability priorities that electric utilities must pursue, listed here in order of best cost/benefit:

1. Peak load shaving (with nighttime load valley filling).
2. Conservation.
3. Bringing renewable energy sources on line.

Sustainability and Maintainability

2007-09-12T07:41:00.000-07:00

Sustainable Housing can be defined as housing that conserves resources as much as possible.

What's the most important resource to the average person? Their MONEY. Therefore, new green built homes should not only aim for zero energy, but also for zero maintenance. Life's too short to paint siding.

Here's the start of my zero maintenance checklist:

1. No exposed, painted wood. Board and Batten wood siding may be used if you make the pledge to let it weather naturally, and turn silver grey, then mottled dark brown.

2. Use large gutters and downspouts. The bigger they are, the less likely they are to clog. Employ scuppers where appropriate, they can be cleaned in a fraction of the time. Pop rivets should be specified in lieu of screws. "Gutter Helmet" type devices are not the silver bullet, but they can help.

3. Consider designing the house to look good with galvanized sheet metal trim. 24 gauge galvanized gutters and fascia will never have to be replaced or even painted in your lifetime. When it does start to rust in 80 years, let it, and go for a rustic look. Failure is still 40 more years out. Of course, copper is even better, but the price/performance is not.

4. Pay a lot of attention to the "splash zone" where rain puts wet mud on the house on the lowest 12"-36"

5. Low maintenance landscaping. Please don't be tempted to put concrete and asphalt everywhere, or astroturf.

6. Fiberglass windows. These really are the only option for zero maintenance windows. Vinyl will crack eventually, and any sort of wood window needs regular painting or varnishing.

Attic Design Update

2007-09-09T21:14:00.000-07:00

The gurus at Building Science have updated their conditioned attic recommendations for every climate. If there is one code requirement that should be implemented immediately, this is it.

And for those roofers and shingle salesmen who always say "It will void the shingle warranty", attic ventilation has very little effect on shingle temperature.

Conditioned attics are now finally allowed in the IRC building code, which Denver uses, but they should be mandatory. They can be accomplished at little to no cost, because they eliminate the often tricky attic ventilation requirements.

The simplest steps to a better wall.

2007-09-03T16:34:00.000-07:00

Two easy changes can be made to conventional wall building:

1. Start by framing on 24" centers:
Optimum Value Engineering
It's hard to get experienced framers to change their ways, but this saves a lot of wood with some extra design time. You have to give them a drawing that shows every stud and header location and configuration.

2. Thermal bridging is a big issue in stud walls. Dow Styrofoam helps at almost no extra cost. Note that it eliminates most of the (rot prone) OSB in the structure, and if you tape the joints, it eliminates all the Tyvek. "Styrofoam insulating sheathing" keeps most of the water at least 1/2" away from all the wood in the house. Nice.

Demand Management

2007-07-18T00:24:00.000-07:00

There has been quite a lot of controversy surrounding the proposed new Xcel towers at Ruby Hill. Does anyone realize this upgrade can be completely avoided with prudent Demand Side Management?

This from the Leonardo Energy website:
"Italy is currently undertaking a programme to install 30 million smart meters. It is estimated that demand-side management tariffs, which limit customers to 3KW of power during peak periods, have reduced peak demand by 5% for 3 hours, 10 days a year. This has removed the need to construct a power station with 2GW capacity to cover the peak demand."

Smart meter technology can also prevent all new powerline capacity upgrades.

Passive Solar Heating is Simple

2007-07-14T02:11:00.000-07:00

I found this European, scholarly, technical paper on Green Building.

Here's my favorite passage:

"3.1 Heating
3.1.1 Passive systems
General considerations The best way to reduce energy consumption is to take advantage of all available natural energy. This is the purpose of bioclimatic design, which is one path to a low energy house. The bioclimatic approach operates at two levels:
1. let the energy of the sun come in
2. do not let it out again"

It really doesn't get much more complicated than that. We've been in our near-zero energy home for 2.5 years now, and have discovered that not only are we saving energy and money, the comfort is amazing.

A relatively overlooked aspect of passive solar is that you want windows with high SHGC (solar heat gain coefficient) on the south side, preferably with overhangs. In the actual marketplace, I have as yet only found only one supplier of these windows, Hurd. Be sure to specify "hard coat" Lo E. In addition, don't "overglaze" the south side, you might get October overheating or need to wear sunglasses indoors.

Now, armed with that advice, find a building site where your neighbor can't block your sun.

Xcel's "Time of Use" energy rates

2007-07-07T23:21:00.000-07:00

Electric utilities are rightly concerned about peak electrical usage, and they spend some effort trying to smooth daily peaks and filling nighttime valleys.

In the 70's Colorado Public Service introduced "off-peak" rates, later called "Time-of-day" rates. This rate schedule was recently discontinued for lack of interest. Coincidentally, they recently offered a new pilot program called "time-of-use" pricing that also aims at that target. Once again, they have developed a rate structure that is too hard to understand and therefore too hard to take advantage of.

2007-06-20T22:22:00.000-07:00

Q. What's a zoning change needed to provide the city's neighborhoods with a sustainable new urban housing option?

A. A change to allow Accessory Dwelling Units in all zones. Truly a win-win-win.

ADU benefits list

2007-06-20T22:11:00.000-07:00

Why is the blog all black?

To save energy, of course:

ABOUT BLACKLE
Blackle saves energy because the screen is predominantly black. "Image displayed is primarily a function of the user's color settings and desktop graphics, as well as the color and size of open application windows; a given monitor requires more power to display a white (or light) screen than a black (or dark) screen." Roberson et al, 2002

In January 2007 a blog post titled Black Google Would Save 750 Megawatt-hours a Year proposed the theory that a black version of the Google search engine would save a fair bit of energy due to the popularity of the search engine. Since then there has been skepticism
about the significance of the energy savings that can be achieved and the cost in terms of readability of black web pages.

Draft Greenprint Denver Residential Design Manual

2007-06-18T09:21:00.000-07:00

Kevin Dickson 2007

Green building is VERY climate/site/zoning/architectural program specific, so Denver needs these specific recommendations to guide design. This draft addresses sustainable homebuilding in the City of Denver with its specific zoning and building codes.

It should be noted that when Quick Wins eliminated Denver's solar bulk plane, there have been few incentives for incorporating solar energy into home design.

Photovoltaic systems are currently preferable to Solar Thermal and Passive Solar. There are many reasons for this, but a few of them have been addressed in comments by Mark Eatherton, one of the country’s most experienced and innovative hydronic and solar heating system contractors, who just happens to practice right here in Denver.

In his words, “But for the mean time, at least here in Colorado where the utiity is REQUIRED to buy back excess electrical production, I'm thinking PV solar makes more sense for the world as a whole. If during the summer months, the dwelling to which the array is attached can not use the electricity being produced by the PV system, it goes back into the grid, helping to offset the demand imparted to the grid from cooling loads.”

When taking this idea further in the R-2 zone, you discover that new construction duplexes don’t lend themselves well to solar. We should allow 22’ wide 2.5 story homes on 25’ lots. Gabled roofs would be the preferred solar configuration. PV cells would be on the south side, silver galvalume metal roof on the north side (see photo). The silver metal is designed to reflect sunlight onto the PV cells of the adjacent house, nearly doubling their electrical output. Optionally, an unglazed thermal collection system such as Dawn Solar or Warm Board could be integrated underneath the PV cells. This thermal energy would be 100% of the domestic hot water load on all sunny days above 40 deg. F.

Ten Percent of the homesites in Denver are excellent candidates for Passive Solar. The side of every lot on the south end of north-south blocks has unobstructed sun. One way to get the word out is to require a consultation with Greenprint Denver’s Passive Solar consultant whenever a zoning application or demolition permit is filed for one of these lots. Edit: As the older neighborhoods get redeveloped, this ten percent could be increased to a potential 30%+ if zone lots on both ends of the block were allowed to be reconfigured in this manner facing south on the avenues:

More incentives needed. City government financial aid helps get the word out about sustainable best practices. Builders are always very slow to adopt new technology because they’ve all been burned by it at some point.

Reuse is better than rebuilding?. Jim Lindberg recently stated “The greenest home is an existing home”, i.e., tearing down and rebuilding isn’t as green as retrofitting the old home. This could be true in many cases, but the concept needs more scientific analysis. A usable basement is high on Denver homebuyers’ wish lists, and a basement retrofit is still financially unfeasible.

Pick one green rating method. The Denver Building Dept. needs to recommend one house rating method among the many. With a little research, we could determine which one gives the best results for Denver’s climate, and is the most user-friendly. All these methods are continually being updated, so using just one means that consumers will be able to compare apples to apples. (This has been addressed in the Climate Action Plan)

ADU’s are picking up steam. Carriage homes and granny flats solve a myriad of problems without creating any. If they are allowed through a change in the zoning code, they should be promoted as a green feature. The roof of a new 2.5 story carriage house is the single best place for a solar photovoltaic system.

Rebuilding existing neighborhoods is far greener than contributing to sprawl by building new subdivisions. Denver has this intrinsic advantage over outlying suburbs. Perceived lower housing costs in the suburbs are offset by higher transportation costs. This point needs to be stressed to young families headed to the cul-de-sacs of Highlands Ranch. Stay in the city and build an addition if necessary.

Superinsulation in new construction and retrofit should be promoted. "The Super-Insulated Retrofit Book" states that you can cut heating requirements about 75-85% on most houses with pre-1970's style insulation (these houses had very little insulation because energy was so cheap). Although IRC requires a high R-factor, stud and header losses even with 2 x 6 construction are high, so a thermal break should be required. Our research has not yet revealed the ideal way to retrofit historic brick homes. Thermally, EIFS is excellent, but you have to turn a brick house into a stucco house, which is not usually a desirable scenario. A “thin brick” veneer brings back the brick look and near-zero maintenance, but doubles the cost. Injecting foam between brick courses is helpful, but achieves R-8 at best. IRC 2006 requires R19 walls. Low e paints should be investigated, inside and out. If the wall is brick veneer on concrete block, the voids in the block should be filled with insulation.

The vented attic is dead. Building science for Denver’s climate prefers conditioned attic space. Add just a couple feet to the attic kneewall, and now you have a cheap and charming bonus room. Vented attics developed mainly because homes leak a lot of air, and water vapor condensed in the cold attic. Venting then became the only way to dry them to prevent rot. The summertime performance under this scenario is even worse, energy-wise. IRC 2006 provides this new conditioned attic detail.

Energy efficient homes and/or homes near transit can qualify for better mortgages. The lenders understand that the buyers will have lower transportation costs. Most families could give up the second or third car.

There should be some financial incentives for TOD in selected areas of change. Maybe a break on property taxes for a few years.

Heat Recovery Ventilators are required by code in Canada. Some local builders are accomplishing the same fresh air supplementation by a simple bath fan that runs 24/7. If HRV costs are reasonable, they should be utilized to recapture the heat in the exhausted air.

Builders need training and encouragement to use evaporative cooling. Edit: Denver City council passed a law to encourage evaporative cooling and discourage central air.

One of the best green builders in the state has told me that he’s afraid to introduce water vapor into a home for warranty reasons. Even though that’s overreacting, a local company, Coolerado, has already solved that problem.
Another reason swamp coolers aren’t used is because they aren’t supported by national HVAC suppliers like Lennox.
Low first cost, and low operating cost. This happy concurrence is rare in mechanical appliances. Sam’s Club price for a 4000cfm unit is under $400.
Many of us Coloradoans with dry sinuses prefer the extra moisture all summer.
Contributes to Global Cooling. On hot days, incoming air is 80F-100F, but the exhaust air is vented from the house at 75F. Conventional A/C units dump huge amounts of hot air into the neighborhood. That’s roughly three times less waste heat into the environment.
To reduce maintenance headaches, they CAN be installed inside, in a vented basement mechanical room. (CAVEAT – this mechanical room MUST have only direct vent gas appliances).
Barometric vent dampers will reduce window management. These dampers are simple, but not readily available yet.

Denver has made a $6 Billion commitment to mass transit. Any R-0, R-1, or even R-2 (low density) zoning should be re-examined within 1/2 mile of a rail stop. The city and the citizens want a return on the light rail investment, and to get cars off the street. Higher density helps accomplish the goals. Neighborhood organizations will always initially oppose this, but Greenprint will start the learning process that higher density near transit is INEVITABLE. Fear of density is still all too common. New York City uses the 50% of the resources per capita of any other city because of density-related economies of scale. Similarly, we can learn from Paris. The typical building is six stories with no front setback. Are the neighborhoods charming? Yes. Is it easy to get around? Yes, but not so much in a car.

Ground source heat pumps are still too expensive for low energy homes. Because of high initial cost, GSHP systems aren’t cost effective for low energy homes under 30,000 BTU/HR design heat loss. The equipment cost won’t be recovered before the equipment needs replacing. Centralized geosystems, however, always make sense in larger multifamily projects and possibly in a neighborhood-wide application.

Use concrete commercial floor systems to increase thermal mass. This could increase comfort, reduce noise, and stabilize temperatures without increasing cost. As part of an overall strategy, this thermal mass can help save nighttime "free-cooling” for daytime. Other thermal mass systems are possible, such as double-drywall systems.

Hot water recirculation BAD, on demand systems GOOD. It takes wasted water and wasted time for hot water to reach far-flung bathrooms. Recirc systems are more wasteful and expensive than on-demand pumps.

Wind Energy. If the site has a good wind regime, these are usually much more cost effective than PV. Denver, however, has relatively little of the steady winds required. Xcel is investing heavily in large, high efficiency wind turbines, and passing the cost savings to us anyway. (Note: The Mercury Café has installed two wind generators near the CBD, so let’s keep an eye on their performance before we completely rule out micro-wind for Denver.)

Smart meters and time-of-use pricing for all homes. Electricity that is consumed in the middle of the night (think off-peak thermal storage systems) should be much cheaper than electricity used in the afternoon of a hot day. Similarly, homeowner-generated PV electricity sold back to Xcel on summer afternoons should cost Xcel MORE than the average rate. Note that the old off-peak demand rates from Xcel were recently discontinued after 30 years because of lack of interest. Let’s not reinvent the wheel that no one wanted. (Originally called “off-peak” rates, then “time-of-day” rates, they were structured poorly and no conventional residences could benefit) Edit: Xcel, on its own initiative, has begun a smart grid city pilot project in Boulder as of March 2008.

This from the Leonardo Energy website:

"Italy is currently undertaking a programme to install 30 million smart meters. It is estimated that demand-side management tariffs, which limit customers to 3KW of power during peak periods, have reduced peak demand by 5% for 3 hours, 10 days a year. This has removed the need to construct a power station with 2GW capacity to cover the peak demand."

20. Keep an eye on LED lighting. The currently available bulbs are too dim and too expensive now, but they have good potential. The service life will be much longer than CFL's, and the light is more pleasing. Edit: LED's are now affordable, if still dim.

21. Greywater Heat Recovery is Easy. GFX Technology manufactures a heat exchanger that reclaims most of the heat from showers that normally goes down the drain.

Greenprint Denver and Climate Action Plan

2007-06-18T08:55:00.000-07:00

Builders interested in capitalizing on the growing "scrape and build" phenomenon in Denver are well-advised to keep up with impending 'green' changes to the building and zoning codes:

Greenprint Denver

Denver Climate Action Plan