AIR TIGHTNESS TESTING
Air leakage is the unwanted and uncontrolled flow of air throughout a building. Referred to as draughts or air infiltration, a common area in which air leakage occurs is around gaps and cracks surrounding external door and windows which are often not visible to the eye. Air leakage is usually quantified as Air Permeability. This is the leakage of air (m3/hour) through the building, per square metre of building envelope (External walls, Roofs, and lowest floors) at a pressure differential of 50Pa between the inside and the outside of the building. .
Why perform an Air tightness test?
With the ever increasing need for higher efficiency buildings, and compliance with current technical guidance document, 'Building Regulation Part L 2008', all new houses must achieve an air permeability of 10m3/hr/m2 or lower. By performing an air tightness test, heat loss due to air infiltration can be limited, thus helping to save energy and most importantly reducing energy bills.
In non-domestic buildings, new buildings for sale or rent require a Building Energy Rating (BER). For most buildings, the rating must be calculated using software called SBEM. Default values of air permeability of 25m3/hr/m2 must be input into SBEM. Most new buildings will perform better than this. Levels below 5 are commonly being reached in well detailed buildings. Reducing the air permeability in SBEM from 25 to 5 has a marked effect on the BER, improving the performance. Therefore testing of non-domestic buildings can often be justified to yield this much improved energy rating, adding to the marketability of the building.
What can Overy & Associates offer?
Pre test site meeting
For contract teams who are unfamiliar with air tightness testing, we can visit site some weeks before the proposed test date for a pre-test visual inspection and snagging.
Ø Review the test procedure, visually inspect the building, prepare a snag list based on the visual inspection.
Ø Agree on provisional date for the actual test.
Ø Agree the surface area of the building with the contractor/ design team for calculation purposes.
Ø Review required attendances.
Ø Agree location for test rig(s).
Whole Building Air Tightness testing
The air permeability tests will be conducted in accordance with the specified standard, IS EN 13829:2000, which is referenced by ATTMA. Results will be reported in writing. Provisional results will be given on site on the day of the test, provided the building envelope area is known.
Air Leakage Audit
Should the building fail to meet the specified air permeability criteria we can assist in locating air leakage routes using the following methods:
Ø Smoke Test
We add large quantities of artificial smoke to the building, then pressurise the building. The locations at which the smoke leaves the exterior side of the envelope will be visible and will be noted.
Ø Thermal imaging surveillance
Thermal imaging detects hot and cold spots using an infrared digital camera. Provided the building is heated to about 10oC above the outdoor temperature, the location that air leaks out of the building will be visible on the outside as infra-red hot spots, usually at junctions and corners.
Overy + Associates were the first company in Ireland to carry out Air Permeability testing.
Overy + Associates have been performing air tightness tests on domestic buildings since 1998 and testing commercial buildings since 2002.
Full Air tightness design review
I t is important that the building has been designed to be sufficiently air tight to meet the air permeability requirements. We can carry out a design review of the drawings and specifications and make recommendations as to particular areas where close attention needs to be paid during construction, or where additional products or details might be applied to increase the probability of a successful outcome.