Analysis of Code-Compliant Construction in Texas Based on Texas Building Energy Performance Standards (TBEPS)

Abstract

This paper presents a detailed technical analysis comparing the stringency of the Texas Building Energy Performance Standards (TBEPS), based on Chapter 11 of the 2009 International Residential Code (IRC) for residential construction and Chapter 5 of the 2009 International Energy Conservation Code (IECC) for commercial construction, to the recently published editions of the IRC and IECC: 2012 IRC for residential construction and 2012 IECC for commercial construction. A series of simulations were performed using the Laboratory's single-family and large commercial office building simulation models based on the DOE-2.1e program and the appropriate TMY2 weather files for three counties representing three 2009 IECC and 2012 IECC Climate Zones across Texas: Harris County for Climate Zone 2, Tarrant County for Climate Zone 3, and Potter County for Climate Zone 4. The analysis determined that the residential provisions of 2012 IRC are more stringent than the 2009 IRC that used the relevant 2009 IECC residential provisions, which is one of the two paths to comply with the 2009 IRC per Section N1101.2 of the code. The annual total source energy savings of the 2012 IRC ranges from 16.3% to 21.4% with the performance path and from 14.3% to 20.1% with the prescriptive path, depending on the climate zone and the heating system type of a house. The analysis for large office buildings also determined that the commercial provisions of 2012 IECC are more stringent that the 2009 IECC. The annual total site energy savings of the 2012 IECC ranges from 7.3% to 11.6% based on site energy use and from 4.1% to 7.0% based on source energy use, depending on the climate zone.