Residential Building Energy Compilations

A. Meier, B. Pon

Three related investigations of energy use in homes are underway. One is a broad compilation of field performance of energy-efficient buildings in both warm and cold climates. Its aim is to identify and document the characteristics of buildings that provide high levels of amenities with low energy consumption. The second investigation seeks to quantify the energy savings from ground source heat pumps (GHPs). The third focuses on the energy use of homes in cold climates around the world. The goal is to understand the apparent differences in energy performance due to differences in the methodology of assessing performance.

The three studies are similar because they require the collection and analysis of large amounts of energy and building characteristics data. They all draw upon a common database containing energy, climate, and physical parameters of the homes. Some of the same buildings are used in all three studies because they are energy-efficient, located in cold climates, and are heated with GHPs. The studies diverge in the treatment of the data.

The first study, the compilation of energy-efficient homes, is a broad effort to show that low-energy homes are not strange or necessarily unconventional structures. Moreover, these buildings achieve low energy use through conventional and reliable technologies, rather than through the efforts or sacrifices of their occupants. This study also seeks to collect data from efficient homes in warm regions, where reducing the cooling requirements is the primary goal.

The second study focuses on the energy use of homes with GHPs. The GHP is a new technology that in theory offers reduced energy use, improved thermal comfort in both winter and summer, and reduced peak loads. Homes equipped with GHPs are being built in a tremendous range of climates, from wintry Montana to semi-tropical Louisiana. Considerable anecdotal evidence suggests that the occupants are happy with both the reduced energy bills and the improved indoor thermal environment, but there is no careful documentation of the energy savings. The Figure shows a comparison of Montana GHP homes with a control group of energy-efficient homes in the same climate region. In spite of the cold climate, space-heating energy (for both groups) is virtually independent of home size. The GHP homes used about 15% less space-heating energy than the controls-a significant difference, but less than that claimed by advocates of GHPs.

Figure. Space heating energy use of Montana homes with ground source heat pumps and controls.

The goal of the third study is to test new indicators of energy efficiency that better capture the home's overall energy efficiency and the levels of services enjoyed by its occupants. In the last 20 years, consumers throughout the world have reduced the energy used for space heating in cold climates. Now the space-heating costs are frequently less than one-third of the entire utility bill, even in near-Arctic climates. At the same time, electricity use in conjunction with space-heating systems (for ventilation and boiler operation) has greatly increased, in addition to the electricity for appliances and water heating. The result is that traditional indicators of residential energy efficiency, based on space heating alone, are increasingly obsolete.

Reference

Litt B, Meier A. What is a low-energy house? In: Proceedings of the ACEEE Summer Study on Energy Efficiency in Buildings., August 28-September 3, 1994. Vol. 9. Washington, DC: American Council for an Energy Efficient Economy, 1994, pp. 9.213-9.220.

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