States doors are often an overlooked component in the thermal integrity of the building envelope. Although swinging doors represent a small portion of the shell in residential buildings. Their U-factor is usually many times higher than those of walls or ceilings. In some commercial buildings, loading (overhead) doors represent a significant area of high heat loss. Contrary to common perception, there is a wide range in the design, type and therefore thermal performance of doors. The 1997 ASHRAE Handbook of Fundamentals will contain expanded tables of door U-factors to account for these product variations. Presents the results of detailed computer simulation of door U-factors. Presents recommended U-factors for glazed and unglazed residential and commercial swinging doors and commercial/industrial overhead and revolving doors.

KEYWORDS: year 1996, Transmittance, doors, commercial, industrial, domestic, revolving doors, swing doors, overhead