A number of provincial governments may in the future taken proactive steps to make thermal efficiency requirements for fenestration products mandatory. A leader in the area of regulations, B.C. has enacted its Energy Efficiency Act which has stipulated that all exterior doors must have a thermal efficiency or U value of 2.0 W/m²
K. In addition, Energy Star requirements for the thermal performance of doors have recently been reduced to a point that no solid wood exterior door can meet these voluntary, well publicized standards. Foam-filled steel and fibreglass doors can easily meet current requirements and expected future tougher requirements when announced. Both mandated and voluntary thermal performance requirements will reduce the market share of Canadian exterior wood door manufacturers to a point that it would drive many of them out of business.
Following the lead of German wood door manufacturers with their success in manufacturing thermally efficient wood doors capable of meet very stringent German thermal efficiency standards, similar approaches were used in this project to develop thermally efficient wood prototype doors that incorporate the use of insulation in the door’s core. Three types of insulation were sourced which are proven to work in improving the thermal efficiency of door. A leading wood door manufacturer with experience in building fire doors was contracted to build eight prototype doors using similar construction techniques found with manufacturing fire doors.
Wood doors with insulation incorporated into doors are capable of exceeding government thermal performance requirements. Depending on both the thermal conductivity of the insulation used and its coverage within the door, the thicker proto-type doors were able to meet an Energy Star Zone D rating — the coldest climate in Canada. This is equal to the thermal performance rating attained by the best of competing foam-filled steel doors.
By adapting their wood door designs to incorporate the use of insulation in the door cores, Canadian wood door manufacturers can regain lost market share taken from them by foam-filled steel and fibreglass doors.