End Use Energy Consumption Estimates For Us Commercial Buildings 1989

An accurate picture of how energy is used in the nation's stock of commercial buildings can serve a variety of program planning and policy needs within the Department of Energy, by utilities, and other groups seeking to improve the efficiency of energy use in the building sector. This report describes an estimation of energy consumption by end use based upon data from the 1989 Commercial Building Energy Consumption Survey (CBECS). The methodology used in the study combines elements of engineering simulations and statistical analysis to estimate end-use intensities for heating, cooling, ventilation, lighting, refrigeration, hot water, cooking, and miscellaneous equipment. Billing data for electricity and natural gas were first decomposed into weather and nonweather dependent loads. Subsequently, Statistical Adjusted Engineering (SAE) models were estimated by building type with annual data. The SAE models used variables such as building size, vintage, climate region, weekly operating hours, and employee density to adjust the engineering model predicted loads to the observed consumption. End-use consumption by fuel was estimated for each of the 5,876 buildings in the 1989 CBECS. The report displays the summary results for eleven separate building types as well as for the total US commercial building stock.

Over the past two decades energy consumption in commercial buildings has been the fastest growing segment among the major end-use sectors in the US. This paper provides a decomposition of the major factors behind the trends in commercial energy use over this period. It examines the impact on overall commercial sector energy intensity from: (1) new buildings, (2) changes in the composition of buildings by geographic region and building type, (3) the growth in office equipment and computers, and (4) the influence of several common envelope conservation measures. A statistical decomposition of historical monthly electricity and gas consumption data is developed to separate energy use into heating, cooling, and ventilation (HVAC) and other components (non-HVAC). This data is then used in conjunction with historical commercial building floor space estimates to derive end-use intensities for these components of energy consumption. Deterministic analyses are performed to estimate the impacts of other factors. The impact of new buildings is measured by estimating the average improvement in heating efficiencies for buildings built after 1980. The effect of building composition on aggregate commercial building energy intensity is based upon estimates of historical floor space by building type and region and building-specific intensities derived from the 1989 Commercial Building Energy Consumption Survey (CBECS). Stocks of various types of office equipment were constructed from industry statistics and independent surveys. The stocks of selected office equipment were combined with estimates of unit energy consumption to estimate the impact on total commercial electricity consumption. For estimating changes in energy intensity due to the building retrofits, the study utilizes a new energy simulation tool developed as part of the Facility Energy Decision Screening (FEDS) system for the US Department of Energy.