Air permeability figure are used in DEAP calculations and poor airtightness can significantly affect the calculated thermal performance of a building.
A reduction in air permeability (@ 50Pa) from 15 (m3/(h.m2 ) to 5 (m3/(h.m2)
= Energy savings of approximately 25%
The air permeability of a building can be determined by means of a pressure test conducted using a device referred to as a Blower door Building Regulations 2011 TGD-L (Dwellings) indicates that reasonable provision for airtightness is to achieve a pressure test result of no worse than 7m3/(h.m2)@50Pa., however best practice is regarded as less than 3m3/(h.m2)@50Pa, with Passive House requirements being less than 1m3/(h.m2)@50Pa.
All Kingspan Century systems, with their factory manufactured applied airleakage measures offer the highest levels of airtightness, typically achieving less than 2m3/(h.m2)@50Pa and can be designed to achieve less than 1m3/(h.m2)@50Pa.
However in traditional construction it is necessary to understand that air leakage routes are complex, and subsequent works such as service penetrations can affect airtightness.