In late 1999, the Commonwealth of Pennsylvania passed legislation to adopt one or more statewide building codes. It is likely that the International Residential Code (IRC 2000) will be adopted for low-rise residential construction. The legislation permits the development of an alternative to Chapter 11, Energy Efficiency, in the IRC 2000 provided that equivalence, in terms of space conditioning energy, is maintained. The Pennsylvania Housing Research Center (PHRC) was asked to develop this alternative version of Chapter 11. Our terms of reference required the development of an alternative, prescriptive, code chapter that would be simpler, more flexible, and Pennsylvania-focused. The PHRC alternative Chapter 11, together with six supplementary reports, was submitted in May 2000. The alternative energy code for Pennsylvania is a significant improvement over the IRC 2000. Two studies--one on glazing ratios and the other on climate--permitted major simplifications with regard to the number of relevant climatic zones and the need for builders to determine glazing ratios for individual houses. A study of light-gauge, cold-formed, steel-framed wall systems provided the basis for a set of more comprehensive recommendations for the selection and placement of thermal insulation to control both heat and moisture flow. Prescriptive trade-offs for greater airtightness, the use of high-efficiency equipment, or both are introduced. Equivalence, with regard to space conditioning energy consumption (conservation), is demonstrated in two studies. One study is confined to thermal envelope considerations and the other involves system (house or townhouse) analysis using POWER-DOE. This paper discusses the changes and the reasons for introducing these changes to the IRC 2000 Code.

Authors: Eric F. P. Burnett, Ph.D., P.E.; Mark R. Fortney

Citation: Thermal Performance of the Exterior Envelopes of Buildings VIII

Keywords: December, Florida, 2001