What are Door Energy Ratings (DER)?
Based on a traffic-light style rating system of G to A, A being the most efficient, door energy ratings were originally launched by the British Fenestration Rating Council (BFRC) back in 2011, stating replacement doors with more than 60% internal face glazing must have a minimum Door Energy Rating of band E (or U-value 1.8W/m2K). Read on.