Air Permeability (Building Fabric)

Building air permeability is the metric describing the air leakage through the envelope of a building.  It can be described as :

“the uncontrolled flow of air through gaps and cracks in the fabric of a building, sometimes referred to as infiltration or draughts”.

There has been extensive research into the adverse consequences of poor air permeability (air leakage) in Buildings, particularly in Europe and the US.  The most significant of these are

• poor air quality from pollution ingress,
• poor thermal comfort control,
• increased energy usage in the building,
• uncontrolled ingress of moisture, and the subsequent potential for mould issues

The measure of air leakage in a building may also be used as a surrogate measure of ‘Build Quality’.

As buildings become more and more energy efficient, the greater the percentage of energy consumption may be due to air leakage, and therefore the importance of ‘building tightness’ will increase over time.

Legislation in the United Kingdom requires all new dwellings (residential) and non-dwellings (commercial and industrial) to verify the building permeability or leakage as part of the mandatory energy efficiency rating.

In Australia, the mandatory disclosure of commercial building energy efficiency is currently enforced using Building Energy Efficiency Certificates or BEECS.  Verifying the assumed leakage rates in Building Simulation allows for greater certainty in performance, whether in NABERS Commitments or Green Star Rating designs or as-built assessments.

QED Environmental Services has conducted a test for a building with a NABERS Commitment of 4.5 Stars.  Assumptions regarding air leakage used in the building energy use simulation were compared to measured values, allowing for greater confidence in the predicted NABERS Rating.

QED Environmental Services can test either the whole building or individual floors, or sections of the building. 

QED Environmental Services consultants have been trained in the tests required when following the ATTMA Technical Standard L2, The Air Tightness Testing & Measurement Association, October 2010.