Estimates of Energy Cost Savings Achieved from 2009 IECC Code-Compliant, Single Family Residences in Texas

Abstract

This report presents estimates of the energy cost savings to be achieved from 2009 International Energy Conservation Code (IECC) code-compliant, single-family residences in Texas compared to the pre-2009 IECC codes, including: the 2001 IECC, the 2006 IECC, and the 2006 IECC w/ Houston amendments (w/ HA). A series of simulations were performed using an ESL simulation model (BDL version 4.01.07 of IC3) based on the DOE-2.1e simulation and the appropriate TMY2 weather files for three counties representing three 2009 IECC Climate Zones across Texas: Harris County for Climate Zone 2, Tarrant County for Climate Zone 3, and Potter County for Climate Zone 4. Two options based on the choice of heating fuel type were considered: (a) an electric/gas house (gas-fired furnace for space heating, and gas water heater for domestic water heating), and (b) a heat pump house (heat pump for space heating, and electric water heater for domestic water heating). The base-case building was assumed to be a 2,325 sq. ft., square-shape, one story, single-family, detached house with a floor-to-ceiling height of 8 feet. The house has an attic with a roof pitched at 23 degrees. The base-case building envelope and system characteristics were determined from the general characteristics and the climate-specific characteristics as specified in the 2001 IECC, the 2006 IECC, the 2006 IECC w/HA, and the 2009 IECC. In addition, to facilitate a better comparison with the 2009 code, several modifications were applied to the pre-2009 IECC codes. As a result, the estimated annual energy cost savings per house associated with the 2009 IECC compared to the 2001 and 2006 IECC are: (a) an electric/gas house: $462/year and $206/year for Harris County, $432/year and $216/year for Tarrant County, and $576/year and $153/year for Potter County and (b) a heat pump house: $490/year and $203/year for Harris County, $487/year and $226/year for Tarrant County, and $680/year and $155/year for Potter County. The corresponding % savings of total energy cost of a 2009 IECC code-compliant house are: (a) an electric/gas house: 22.7% and 10.1% for Harris County, 21.8% and 10.9% for Tarrant County, and 28.9% and 7.7% for Potter County and (b) a heat pump house: 21.6% and 8.9% for Harris County, 20.9% and 9.7% for Tarrant County, and 25.7% and 5.8% for Potter County.