Insulating exterior walls as part of energy-efficiency measures for the whole house can significantly reduce energy consumption and save heating and cooling costs. Three strategies are presented in this guide, including the top-up strategy previously discussed, and two major retrofit methods where insulation is added to the interior or the exterior of the existing insulation. While major insulation retrofits are more intrusive they are generally more cost effective when combined with interior or exterior work already taking place. The potential energy savings can also be a compelling reason to initiate work.

See the Guide entitled BC Housing - Best Practices - Windows and Doors, and the industry guide Best Practices for Window and Door Replacement in Wood-Frame Buildings published by the Fenestration Association of BC and BC Housing (see Resources at the end of this Guide) for more information on how to integrate windows and doors into an insulation retrofit project.