Sunday, October 9, 2011

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

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.

Friday, October 7, 2011

2011 LED Lighting Update

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

Monday, August 15, 2011

Important New Solar Tank from Bradford White


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

Here's the description:

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 the top 40-60 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 per day to the room they are in.  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

Friday, August 12, 2011

Heat Pump Water Heaters Redux

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

Tuesday, August 9, 2011

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

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.

Sunday, June 26, 2011

Praise for Swamp Coolers (in Denver)

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 AC 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 AC 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.

Sunday, May 1, 2011

Earth Advantage Institute's Top Ten List


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/