National Energy Savings Potential of Zero Energy House Kits

Submitted by: Jeff Christian, Buildings Technology Center

One of the projects underway in the Buildings Technology Center is the development of affordable zero energy house kits. After at least a full year of detailed measurements in three occupied prototype kit houses in Lenoir City, TN, and eight months of a fourth, our findings are that you can construct these houses for around $100,000 and after the solar credits from TVA, cost the home owner, on average, less than $1.00 per day over a yearly cycle. These houses are made from Structural Insulated Panels prefabricated and shipped to the site already for doors, windows and electrical wiring. Once the envelope is up, weather barrier system installed, all openings flashed, windows, and doors set, the air tightness can be confirmed at less than 0.1 air changes per hour by a blower door test. All ducts are located inside the conditioned space therefore not pulling in any unwanted cold air into the house in the winter or hot moist air in the summer.

The house is orientated to bring in plenty of delightful daylight and minimize summer time overheating by extended overhangs and minimum usage of west windows. Pressure balancing provisions are designed into the HVAC system so there is very little risk of pulling unwanted moist air into the walls, roof, or floor. This also eliminates the risk of pulling in radon, termites or odors from outside the house. The house has fresh air always coming into the building in a controlled manner to satisfy Indoor Air Quality requirements of the American Society of Heating, Cooling and Refrigerating Engineers Standard 62.2. So the house is a very healthy environment to spend most of your time when you're not out at the Lab all hours of the day and night.

The house uses as many florescent lights as practical. Liberal use of indirect lighting from sconces with CFL and tube florescent in the kitchen. All energy star appliances and a Heat Pump water heater that also help the refrigerator and provide some welcome nice cool dry air particularly in the summer.

The house has geothermal heating and cooling which means no ugly-noise box hanging around the patio outside. Now the only noise box is coming from your teenager's bedroom. On the roof is a long lasting metal roof to give you that soothing tone of rain drops that everybody keeps singing about. Also this roof is completely recyclable unlike those shingles that are most likely on your current house. Did you know that extending roof service life from 15 to 30 years can save $5.4 billion per year and reduce waste by 0.16 billion ft³/yr? This roof waste savings alone totals 1.6% of the U.S. total solid waste, much going into unregulated C&D landfills.

Then we frost this delicious house with solar modules that make energy from the sun. To sweeten the deal even more we get money from TVA for every kWh we produce. It gets even better. All your friends can help by buying green power from TVA at a premium. Even if they can’t have all the fun and feel good that comes from the satisfaction and pride of walking the talk and being a terrific environmental Steward by having a Prius in the driveway of your home zero energy sweet home. It even gets better than that, because you can read about how this beautiful Rocky Top country is actually not EPA compliant with air pollution requirements for ozone and 2.5 micron particulate matter and you aren’t part of the problem. It keeps getting better, you can know that back in the day the grid went down on 50 million folks in the Northeast on August 14, 2003, the first prototype near zero energy house generated 8 kWh that day and the hour before the 4:00 PM crash 1 kWh. You will not be contributing to grid stress, in fact your house will most likely be supplying into grid on peak hot summer afternoons during demand periods.

In summary, you will not only be able to tell your grandkids that you had the most fantastic career at ORNL, some under the ESTD Banner, by actually earning a living helping to save the earth by your contributions to energy efficiency and other national needs, but you lived your life with a very light footprint on this fragile planet. Imagine the glow in your grandkid’s eyes. You will be their hero. They will admire your life so much that they will go right to their studies and learn to live their life and choose their career paths to be just like you. They will all earn Ph.D.s and lots of money and use that money in good ways just like you by buying more zero energy house kits that were invented at ORNL back in the beginning of the new millennium.

To show you where we are heading with our zero energy project please see the fact sheet “Efficient Technologies for Affordable Zero Energy Buildings”.

Ok! Now that you have an unbiased idea of how wonderful it would be to have your next house start with a zero energy house kit, I need some help. Please answer four simple questions.

Please Email ChristianJE@ornl.gov

When I asked the Tellico Village Rotary Club those questions this is the energy data I received. The average daily cost reported was $4.73. This data was collected in June 2004. One reported cost of $8.05/day. The low value under $3 was an apartment dweller.

The same group answered question three with a reported average willingness to pay 10.5% for a house that started with a zero energy kit. Several responders from this group of primarily retired folks now living in Tellico Village said they would be willing to pay as much as 30% more for a house with zero energy bills.

In the cover story of the January 2005 issue of Mother Earth News, the author Amanda Griscom Little asked if anybody was interested in forming a buyer group to negotiate mass buy purchase prices for key components of zero energy house kits or maybe even whole ZEH kits. The response has been that 831 emails have arrived in Jeff Christian’s inbox. Many of these have whole developments in mind. One is looking to build 2500 units. Just for grins are any of you interested in going in on this deal?

P.S.
We just got our first payment from Wal-Mart to monitor the new McKinney, TX, super center that is topped with five different solar PV systems, two windmills, and a bioboiler burning lube oil mixed with cooking oil from the grill. Roof water runoff into a simulated wet lands to clean and use for irrigating the trees helping to cool the Wal-Mart shoppers parked cars. I have had six telephone conversations with Wal-Mart folks about sitting a zero energy house kit in the parking lot right next to the pond. So stay tuned, you might be able to pick up one of these zero energy house kits along with your groceries, and other cost cutter items on your next run to the store.

National Energy Savings

This project promotes affordable housing that meets the DOE Building Technologies, Building Integration element’s Multi-Year Plan performance goals. This will help such housing become available to the middle- and lower-cost segments of the housing market. Moreover, by increasing the affordability of energy efficient housing technologies, attainment of future, higher level performance goals will be facilitated for high-as well as-low cost housing. When the cost of energy efficient technologies is lowered, additional energy savings measures can be incorporated in a house while still meeting the MYP requirement for zero or less cash flow. Thus, this project provides enabling technology for overall, integrated building efficiency improvements.

Estimating energy savings from a broad spectrum of component technologies many of which are being worked on in the HVAC and Building Envelope groups in ESTD is difficult. Therefore, a conservative bound on the energy savings for the integrated efficiency improvements for which this project provides enabling technology is estimated. Actual energy savings are expected to be larger than what is calculated here.

First, the percentage of energy savings must be calculated. The basis for this number will be actual, measured savings. Four, prototype, Building America, near zero energy houses have been built in partnership with Habitat for Humanity (HfH). Detailed measurements of the energy use by these four houses have been made for a full year. Comparing the average energy use from these four houses to the average energy use of 12 other houses in the same HfH subdivision, but built with conventional technology, shows that the near zero energy houses use 45% less energy. [Christian, ASHRAE Journal, January 2005] This is illustrated in the graph provided below, which shows the annual energy use of a representative sample of the conventional houses compared to a sample of the near zero energy houses.

The figure of 45% is conservative because it does not take into account expected future improvements in energy savings. It is also less than the Building America goal of 50% average energy savings by 2012.

To estimate the expected market penetration for highly energy efficient homes, refer to the National Assocation of Home Builders (NAHB) Research Center report, “The Potential Impact of Zero Energy Homes.” This report estimates a market penetration potential of 70% for highly energy efficient homes, given appropriate incentives. Establishment of just these types of incentives is included in this project. TVA, the nation’s largest public utility, offers financial incentives for green power generation. This can serve as an example for utilities across the nation, and this project will establish the basis for extending these incentives to such technologies as solar water heaters and low-cost geothermal heat pumps. It is thus appropriate to use the NAHB figure as a basis for market penetration. However, to ensure that a conservative figure is used in the present calculation, we will reduce the estimated market penetration to 50%; that is, we assume that 50% of new homes built will utilize this highly energy efficient technology.

We must now estimate how much of existing housing stock will be replaced with new homes. Each year we replace about 2% of our housing stock (2004 Buildings Energy Data Book). Between 2012, the date for the Building America goal of average home energy savings of 50%, and 2050 is a period of 38 years. During this period (2%/yr x 38 yr) = 76% of our housing stock will have been replaced by new homes. With 50% of these new homes utilizing highly energy efficient technology, we can conclude that a total of 38% of the housing stock in 2050 will attain the cited level of energy efficiency. Note that this figure is conservative, as it ignores all the homes built between now and 2012, some of which will certainly also incorporate this technology.

Given that the residential sector currently uses 22 quads [2004 Buildings Energy Data Book], we can now perform the energy savings calculation:

This represents a conservative estimate of the energy savings in 2050 from the highly energy efficient new homes for which this project provides enabling technology.

Note that many of the technologies included in this project will be applicable to retrofitting existing homes to improve their energy efficiency. As affordable, highly efficient technologies become more common in the market, it is certain that some will be applied to existing homes, generating still more energy savings. We feel confident that a market penetration of 30% for technologies with cumulative energy savings of 20% is achievable, which in turn would imply another 0.3 quads of savings:

24% existing homes x 20% savings x 22 quads x 30% penetration = 0.3 quads

So this is the basis for why I told President Bush on March 9, 2005 in Columbus OH, that the R&D on zero energy buildings will save about 4 quads per year.

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