October 16, 2009
Mixed Humid

Side-by-side energy testing and monitoring was conducted on two houses in Louisville, KY. Both houses were identical except that one house was constructed with conventional U.S. 2x4 studs and a truss roof while the other house was constructed with stress-skin insulated-core panels for the walls and second floor ceiling. Airtightness testing included fan pressurization by blower door, hour-long tracer tests using sulphur hexafluoride, and two-week-long time-averaged tests using perfluorocarbon tracers. Thermal insulation quality testing was done by infrared imaging. Pressure differential testing resulted in recommendations to used sealed combustion appliances, and to increase return air flow from closed rooms. By calculation, the conductive building load coefficient (UA) differed by only 2% between the two houses. Heating energy-use monitoring showed savings for the panel house of 12% with electric heating and 15% with gas heating. A comparison of the two monitoring periods showed that the combined efficiency of the gas furnace and the air distribution system for both houses was close to 80%. Measured energy-use regression models with Typical Meterological Year weather data gave a prediction of seasonal energy savings of 16% for electric heating and 19% for gas heating. Seasonal heating energy-use predictions were also made with the DOE2.1E hourly building energy simulation program, which gave savings of 7% for electric heating and 6% for gas heating. The discrepancy between savings predicted by measurement and simulation may be related to rated performance versus field performance of insulation systems. From the data, it appears that this type of industrialized construction has energy efficiency advantages over conventional construction.