Saturday, December 10, 2011

The Folly of Suburban Greenfield Development

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*:

* 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.

Sunday, October 23, 2011

Lighting Efficiency Summary, 2011

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:

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. 

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:

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:

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:

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

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 ( 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.

Tuesday, April 19, 2011

New Passive Solar Domestic Hot Water System Debuts

There’s a new passively pumped solar water heating system
that greatly simplifies the typical cold climate domestic hot water (DHW)

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:

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

And why it fizzled:

The patent can be viewed at

Thursday, February 24, 2011

Xcel Drops PV Rebates!

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...


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? 


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

Tuesday, February 15, 2011

Finally a Consumer Friendly Home Energy Rating System

I've finally found my dream house rating system, which is just like an EPA rating label for an appliance or a car:
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.pdf811.7 KB

Wednesday, February 9, 2011

Your New Construction Greenbuilding in Denver Checklist

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 3/8" 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.

Saturday, January 29, 2011

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

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 $'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.

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.

Tuesday, January 18, 2011

Denver's Zoning Now on the Cutting Edge

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:

" 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.

Sunday, January 9, 2011

The Advantages of Neighborhood Photovoltaics

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.