Technical Booklet F2 Conservation of Fuel and Power in Buildings Other Than Dwellings·Page 51·Table 3.1
Table 3.1: Opening areas in the extension
Maximum glazing percentages for windows, personnel doors, and rooflights vary by building type, ranging from 15–40% of exposed walls and 20% of roof area, with exceptions for buildings with vehicle access doors and smoke vents.
Building type | Windows and personnel doors as % of exposed wall | Rooflights as % of area of roof
Residential buildings where people temporarily or permanently reside | 30 | 20
Places of assembly, offices and shops | 40 | 20
Industrial and storage buildings | 15 | 20
Buildings with vehicle access doors, display windows and similar glazing | As required | N/A
Buildings with smoke vents | N/A | As required
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