Cost Effective Levels of Thermal Insulation for Basements in Canadian Housing

This paper is based on recently completed research funded by Canada Mortgage and Housing Corporation to investigate cost effective levels of thermal insulation for basements in Canadian housing. The work is an update of a life cycle economic assessment appearing in Performance Guidelines for Basement Systems and Materials Project undertaken for the Institute for Research and Construction, National Research Council Canada in 1999. Since that time, the cost of space heating energy has escalated sharply and new methods and materials for insulating basements have emerged. The paper addresses the conference themes of new research and revised design understanding, and basement construction methods. A methodology for energy modeling and life cycle cost analysis is presented in the first part of the paper followed by an assessment of the energy efficiency of current practices. These results are then contrasted with cost effective alternatives when several energy price escalation rate scenarios are examined using the Modified Uniform Present Worth method according to ASTM E 917, Measuring Life-Cycle Costs of Buildings and Building Systems, ASTM Standards on Building Economics, Fifth Edition, 2004. The final part of the paper presents recommended basement envelope assemblies for achieving cost effective levels of energy efficiency while improving basement system performance with respect to moisture protection, thermal comfort and reduced susceptibility to mould. The paper is of interest to designers, builders and house occupants because basements are increasingly becoming viewed as liveable spaces that are expected to perform as well as above-grade areas of the building. For energy policy and building code agencies, the substantial energy savings cost effectively afforded by advanced basement envelope systems are compelling factors to update minimum thermal insulation requirements for basements.