Modeling climate-driven changes in U.S. buildings energy demand

Abstract

How climate change might impact energy demand is not well understood, yet energy forecasting requires that assumptions be specified. This paper reviews the literature on the relationship between global warming and the demand for space cooling in buildings. It then estimates two key parameters that link energy for space cooling to cooling degree days (CDDs) using data for nine U.S. Census divisions, which is the spatial resolution of the National Energy Modeling System (NEMS). The first parameter is the set point temperature for calculating CDDs; the second is the exponent for representing the relationship between changes in CDDs and changes in electricity consumption for space cooling. We find that the best-fitting CDDs have a set point of 67 °F (19.4 °C), for both residential and commercial buildings, rather than the conventional 65 °F (18.3 °C). Set points also vary by region, with warmer regions tending to have higher set points. When CDDs are based on the conventional set point, the best fitting exponent is 1.5 for both residential and commercial buildings, indicating that space cooling is more climate-sensitive than is specified in NEMS. As a result, the official projections of U.S. energy consumption would appear to underestimate the energy required for space cooling.