Air permeability is one of the major sources of heat loss from a building's interior, contributing to higher building running costs and increased CO2 emissions.
Critical to achieving good air tightness is the flexibility of the cladding system in accommodating variances in steelwork tolerances. Reducing air permeability is a major factor in demonstrating compliance with the latest changes to Part L of Building Regulations. Part L 2010 states a minimum 10.0m³/hr/m² at 50Pa. The NCM (National Calculation Methodology) advises a minimum of 5.0m³/hr/m² at 50Pa.
Good air permeability aids in delivering EPC ratings in Band A.