Heat loss characteristics of the ELCAP residential sample

Abstract

The fundamental purpose of this study is to analyze heat loss characteristics of the End-Use Load and Consumer Assessment Program (ELCAP) samples of residential buildings and compare these results in a regional context. The two basic objectives of the analysis are to determine the distribution of insulation levels and heat loss potential among the various building components in existing homes as a function of construction vintage and climate zone, and to calculate theoretical residential heat loss potentials for use in subsequent analyses. The vintage and climate zone dimensions explored in this analysis are of particular interest in testing the extent to which the sample supports the general perception that newer houses and houses in colder climates tend to be better insulated than older houses and houses in warmer climates. The distributions of overall heat loss potential and insulation levels, for the houses as a whole and for the houses excluding the foundation, are examined. The effects of house size, shape, and foundation type on these distributions are also examined. Similarly, the distributions of effective insulation levels for each building envelope component are developed. The sample weighted average heat loss potential for each envelope component is also determined by climate zone, to provide information about the relative heat loss through components that are the targets of energy conservation retrofit programs. A principal result of this analysis is the information that home insulation levels are primarily related to vintage rather than climate severity, at both the whole house and component levels. The sole exception to this trend is windows, which exhibit a trend in climate zone but not vitage. The general trend toward vintage as a determinant of thermal integrity of residences may be the consequence of a lack of climatically appropriate energy standards. This illustrates that the lost opportunities for achieving an energy-efficient housing population can be large in the face of a tendency to build to common practices that are not adapted to particular climates. It should also be noted that the historical trend toward larger homes does result in higher thermal conductance, but this is more than compensated by the trend toward increased insulation levels. The homes built to the Model Conservation Standards clearly exceed the historical trends when they are viewed as representative of the next decade of construction.