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Description: This 49-page report provides the thermal performance of 11 different structural wall systems: concrete masonry, insulated cast-in-place, insulated concrete forms (ICFs), and autoclaved aerated concrete (AAC) as well as wood and steel frame. The results illustrate the benefits of thermal mass, depending on climatic conditions for most of North America.
Based on Department of Energy software, researchers modeled a typical single-family house design (2,450 sq ft) to test energy consumption in 25 cities (25 ASHRAE zones) across the U.S. and Canada. For each location, the researchers create models of 11 different exterior wall systems: conventional wood frame, steel frame, AAC, concrete masonry units, ICFs, and insulated concrete hybrid walls with exterior insulation or interior insulation. Typical materials went into the design to meet or exceed the minimum energy code requirements of the 2000 International Energy Conservation Code for U.S. locations, or the 1997 Model National Energy Code of Canada for Houses for Canadian locations. Annual energy use was based on heat flow through exterior walls (R-Value and U-value) and thermal mass effects.
Analyses showed that energy for heating and cooling accounted for 20 to 72 percent of the total annual energy cost, depending on the location. Due to the thermal mass of the concrete walls, houses with concrete walls had lower heating and cooling costs than houses with conventional frame walls, except for locations where the concrete walls were extremely under-insulated.
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