Buildings XI Conference -- The TVA Dollar-a-Day Energy Cost 235 m2 Research Home PDF

In 2008, a demographic study was conducted on what represents the market for builder spec homes in the mixed-humid climate region served by a large electric utility. Several builders were interviewed and one was selected to construct a trilogy of research houses of similar size, orientation, window area, and exposure. One house captured what was representative builder “spec” construction in 2008, one was the same as the builder house but provided an extensive energy-efficiency retrofit package, and the third was a Home Energy Rating System (HERS) 34 high-performance house with highly efficient envelope, energy recovery ventilator, solar photovoltaics, and solar water heating.

This paper provides a measured performance comparison between the builder house with a HERS 101 and the HERS 34 high performance house. The envelope’s measured comparisons cover the R-22 h·ft²·°F/Btu (3.9 m²·°C/W) hot box measured flash and blown-in fiberglass optimum value framed walls, R-49 h·ft²·°F/Btu (8.6 m2·°C/W) vented attic with radiant barrier on the underside of the roof sheathing, R-6 h·ft²·°F/Btu (1.1 m2·°C/W) triple layer windows, airtight construction, ach @ 50 Pa of 2.4, and zero energy duct loss to the outside. The HERS 34 high-performance house has a 2 ton seasonal energy efficiency ratio of 16 Btu/ Wh (16.8 kJ/Wh), a heating season performance factor of 9.5 Btu/Wh (10 kJ/Wh) air-source heat pump compared to the International Energy Conservation Code (ICC 2006) 2006 code-compliant air-source heat pumps with a total capacity of 4 tons (14 kW) in the builder house.

These are research houses with identical simulated occupancies with the first full year of measured performance and a neutral cash flow analysis completed. These houses will be reconfigured every year with technology retrofits that will continue to strive toward neutral cash flow net-zero grid energy performance until at least 2012.