Technical Booklet F1 Conservation of Fuel and Power in Dwellings·Page 31·2.47
Maximum Air Permeability Requirements
Maximum permissible air permeability is 10 m³/(h.m²) at 50 Pa, with an expectation of 5 m³/(h.m²) or less; below 3 m³/(h.m²) requires consideration of mechanical ventilation alternatives or specialist advice.
The maximum permissible air permeability is 10 m3/(h.m2) at 50 Pa however, it is expected that dwellings will normally have an assessed air permeability of 5 m3/(h.m2) at 50 Pa or less. Where an air permeability of less than 3 m3/(h.m2) at 50 Pa is a likely outcome, consideration should be given to alternatives to natural ventilation, such as a continuous mechanical extract ventilation system, or to seek specialist advice in order to ensure adequate indoor air quality. Heat recovery will further improve energy performance on mechanical systems. Guidance on these systems is provided in Technical Booklet K.
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