Comparison of building enclosures designed to the minimum requirements of the 2011 NECB

The objective of this study was to compare the life cycle costs of lightweight and thermally massive building enclosures designed to meet the prescriptive requirements of the 2011 National Energy Code of Canada for Buildings (NECB) in Edmonton, Alberta, Canada. Nine enclosure systems matched to three buildings (office, school, and apartment) were designed to meet the NECB requirements. Energy costs were estimated from local energy prices and hygrothermal analyses conducted using WUFI Plus. Construction and maintenance costs were estimated using “bids” from local contractors and RS Means cost data. Life cycle cost analysis (LCCA) was carried out and the enclosures were compared based on equivalent annual cost. LCCA demonstrated that the high initial cost of heavier materials is largely offset by greater durability and reduced sensitivity to moisture. Despite relatively low initial costs, EIFS on stud framing was shown to have very high life cycle costs if not properly maintained.