Standards for controlled fittings

Fitting Standard Windows, roof windows and glazed rooflights(1) 1.8 W/m2.K for the whole unit Alternative option for windows in buildings that are essentially domestic in character(2) A window energy rating(3) of Band C Plastic rooflight(4) 1.8 W/m2.K Curtain walling See paragraph 3.63 Pedestrian doors where the door has more than 50% of its internal face area glazed 1.8 W/m2.K for the whole unit High-usage entrance doors for people 3.5 W/m2.K Vehicle access and similar large doors 1.5 W/m2.K Other doors 1.8 W/m2.K Roof ventilators (including smoke extract ventilators) 3.5 W/m2.K Notes: (1) Excluding display windows. (2) For example, student accommodation, care homes and similar uses where the occupancy levels and internal gains are essentially domestic in character. (3) See Technical Booklet F1 for more detail on window energy rating. (4) The relevant rooflight U-value for checking against these limits is that based on the developed area of the rooflight, not the area of the roof aperture. The developed area of a rooflight is explained in NARM Technical Document NTD 2 (2010) Assessment of thermal performance of out-of-plane rooflights.