Use exterior doors rated at a minimum of R-4
Wood doors are poor insulators
Wood is safely traditional but with an R-rating of about 1 per inch not a very effective thermal insulator. Instead, use insulated steel or fiberglass exterior doors with a rating of R-4 or greater. Glass panels in doors can lower insulating qualities, so keep that to a minimum and eliminate sidelights if possible.
Learn more in the Green Building Encyclopedia
Learn more in the Green Product Guide
