Evaluation of Affordable Prototype Houses at Two Levels of Energy Efficiency

Two high performance prototype houses were built in Carbondale, Colorado, as part of the U.S. Department of Energy's Building America (BA) Program. Each prototype was a 1256 ft2 (117 m2), 1-story, 3-bedroom house, and met the local requirements for affordable housing. The National Renewable Energy Laboratory (NREL) performed short-term field testing and DOE-2.2 simulations in support of thisproject at the end of December 2004. We also installed long-term monitoring equipment in one of the houses, and are currently tracking the performance of key building systems under occupied conditions. One of the houses (designated H1) included a package of cost-effective energy efficiency features that placed it well above the Energy Star level, targeting a Home Energy Rating System (HERS)score of 88-89. The other (designated H2) was a BA research house, targeting a HERS score of 94-95, and 45% whole-house energy savings compared to the BA Benchmark. Preliminary results from the field evaluation indicate that the energy savings for both houses will exceed the design targets established for the project, although the performance of certain building systems, including theventilation and foundation systems, leave some room for improvement.