Eric Doub, President and Founder - Ecofutures, (Courtesy of Ecofutures)

Zero Net Energy Homes that produce as much energy as they consume are a great option for people who want to limit their greenhouse gas emissions while eliminating all monthly expenses associated with an energy or utility bill.  The B-GC spoke to Eric Doub, President and Founder of Ecofutures, Inc., one of the few companies in the U.S. that specializes in the building of such homes.  For a glimpse of what may be the future of homes in the U.S. read on.

:   Can you start off by telling me a little about Ecofutures, including its history, its market and its business direction?

Eric Doub: I started Ecofutures in the early 1990s by retrofitting homes to make them  super efficient and healthy, and in 2005 built our first so called zero net energy home.  We define this as a grid-tied home that produces on average as much power as it consumes.  Currently, the luxury, carbon neutral homes we are building are all in the Denver, Colorado metro area, but we are getting requests to be part of design teams in Washington State, New Mexico and the Boston area.   Our business direction is expanding to include homes across the cost structure, from lower income, factory built, zero net energy homes to the kind of luxury, zero net energy homes we started with.  The growing awareness of our unique skill set in building energy efficient, high performance  homes has led us to do consulting for neighborhoods and communities and to work with developers and architects who want to use our skill set in the energy efficiency area.  Our reputation for building healthy, beautiful, durable, comfortable zero net energy homes has opened up a lot of new opportunities for us.

:  How many Zero Net Energy Homes have you built?  What is the HERS range for homes that you have built?  How much cost does the Zero Net Energy feature add to the cost of your homes? (For information on the HERS index read ‘How Energy Efficient is Your Home’.)

Eric Doub: We have completed 4 homes that are zero net energy homes.  We have done a renovation on one home to convert it to energy neutrality, and are now in the process of building two additional zero net energy homes, which we expect to complete by summer 2010.  The HERS index of the 4 homes we have built have been verified to range from 19 to -3.  The one we built with a HERS index of 19 is not truly net zero, but in that case, the objective was to build a nearly zero net energy home.

The added cost to bring a home from a standard energy use home with a HERS index of 100 to zero net energy is about 5% to 8 % of the home’s normal price.

:   Can you tell us how your Zero Net Energy  home specifications differ from non-Zero Net Energy homes?  Insulation?  Electric power sources?  Home heat and hot water?  Lighting and energy efficient appliances?   Are there company partners/contractors you work with when you design and build a Zero Net Energy home?

Eric Doub: Let me answer this question by referring to a home we built in North Boulder, CO, one we call the Solar Harvest home (see Figure 1).  This home, built in 2005, is just under 5,000 square feet in size.  The home consumes about 10,000 kwh/year and has an 8.74 kw PV system generating over 12,000 kwh/year.  Of the 10,000 kwh/year consumed, only about 1600 kwh is needed to electrically heat the home through a Colorado winter, just a small fraction of the power that would be required to heat a conventionally built home.   In addition to the PV, we used salvaged 1980s flat plate solar collectors from Novan Solar for hot water with a large solar storage tank.  In other homes, I have used Thermomax evacuated solar collectors, which are slightly more effective than the flat plate designs in low temperatures and mixed solar gain conditions.

Figure 1: The Solar Harvest Zero Net Energy Home built by Ecofutures. (Courtesy of Ecofutures)

Heating requirements are kept low by using the best windows and a thermal break system for insulation.  We use Fibertec energy efficient windows and Icynene polyurethane spray foam insulation.  Standard wall assemblies transfer about 50% of the heat from the indoor drywall to the outdoors.  In our homes, we break the normal thermally conductive path by creating a gap and then filling it with the spray foam.   The home is sufficiently well insulated so that the heating system is required only after a couple of cloudy days with temperatures in the teens.  On sunny days, it is not likely to need heating even with outdoor temperatures below -20 F.

For air conditioning we use the Coolerado system, which uses only about 20% of the power of a standard air conditioner.  For most kitchen appliances we use Consumer Reports findings to select those with the highest efficiency.  With regard to lighting, we often use a lighting designer who is up to speed with the latest, lowest energy and most pleasing lighting products.  We use a lot of compact fluorescents and are starting to use more LEDs.

:    Can you tell us if you are seeing an increased interest in Zero Net Energy homes recently?   Is there something about your area of Colorado that leads to a higher level of market interest in Zero Net Energy housing?

Eric Doub: There is a huge increase in interest.  However, the total number of zero net energy homes is still small.  Though homes are being built with more emphasis on energy efficiency, the percentage of new homes that actually achieve zero net energy is very small.

Yes, Colorado residents seem to be particularly interested in keeping their environment clean out of concerns for climate change and national security.  Not surprisingly, a number of the people I build homes for also have electric vehicles.  One home I designed had to have provisions for charging a converted plug-in Pontiac Vibe.  Another home, I am planning for completion this summer requires that I allow for a plug-in electric Tesla vehicle, expected to consume 2,800 kwh/y based on an estimated driving distance of 15,000 miles.

:   What kind of federal or state subsidies are there for Zero Net Energy homes?  If these exist, do you handle the paperwork completely and include the benefit in the home price?

Eric Doub: There are various incentives and tax credits.  In addition to the usual renewable energy incentives, there are tax credits for getting a HERS rating of 50 or better.  Consider the following reference for more information.

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