Many buildings fail airtightness testing
Around a third of buildings tested by BRE are failing the airtightness test two-and-a-half years after the introduction of Approved Document L2. The news emerged just as as the consultation document for the latest Part L on energy efficiency was released by the Office of the Deputy Prime Minister. Mike Jaggs, head of BRE’s airtightness service, says, ‘A large number of companies still appear to be unaware that Building Control have to be satisfied that a building is airtight before it can be signed off. This means that designers and contractors are not addressing the issue at the start of a project when it is very often quite simple to put in place the right design and workmanship principles. ‘Failing the test means having to go back and redo work in the final stages of construction, and this is very costly, both in time and money. It comes as quite a shock to clients when they suddenly realise they haven’t designed or built for airtightness.’ The new Part L sets a target for the improvement of building energy performance of 25 to 35%, which is expected to require innovation in products, including renewables integrated into building components. Part L2 requires all non-domestic buildings to demonstrate that they are airtight, either by reviewing designs with Building Control or by putting the building through an airtightness test in the final stages of construction. For buildings over 1000 m2, the Office of the Deputy Prime Minister recommends testing. BRE’s experience is that companies that manage the process properly have no problem getting their buildings through the test. Mike Jaggs, comments, ‘It’s a matter of attention to detail. Everyone needs to know what has to be done and why. Success doesn’t depend on building type; complex buildings can pass and simple buildings can fail.’ Building-control bodies seem to be inconsistent in the way they apply the air-permeability requirements. Some are more strict than others, and BRE feels that this could be improved. ‘It is important to iron out these differences and have everyone working to the same standards,’ says Mike Jaggs. ‘They aren’t difficult to achieve; it’s just a matter of learning what to do on your first building and then rolling the process out on following projects.’
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