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Measuring Building Performance - Testing For Airtightness With the introduction of energy efficiency standards for new housing the construction industry is now having to build tighter buildings that limit airflow into and out of a building. The tighter the construction the more efficient a building is at limiting energy flow associated with uncontrolled air leakage. 20% of a building's heating and cooling can be lost through uncontrolled air leakage of the building envelope. New, highly energy efficient residential buildings should have a natural air leakage rate* of no greater than 0.5 air changes per hour natural (achnat). Internationally, the accepted range for energy efficient housing is between 0.3 and 0.5 achnat. Improving Energy Efficiency of Existing Buildings The majority of existing houses have been built using techniques and materials that cannot ensure
such a tight construction and as a result air leakage is a major problem. Existing older buildings
can have air leakage rates of up to 3.0 achnat. The average housing stock in Victoria has an
average leakage rate of 1.49 air changes per hour natural (achnat) (pub. Energy Victoria 1992). |
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To begin to retrofit an existing building to try and reduce energy consumption requires a detailed and
accurate understanding of the rate and nature of air leakage of the building. There are now available specialist tools that can measure air leakage of a building and assist in energy conservation. One such tool is the "Blower Door". Blower door technology is used in many countries, where energy efficiency is mandated, to measure the airtightness of building envelopes, diagnose and demonstrate air leakage problems, estimate natural infiltration rates, estimate energy efficiency losses from building air leakage, and certify construction integrity. The results of a blower door test will indicate where air leakages occur. Given this information appropriate and targeted tightening of a house can occur. |
 Blower door measurements being taken. |
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There are many house-tightening measures that can be undertaken to reduce air leakage and improve energy efficiency in a house. Typical measures such as weatherstripping doors, caulking windows, adding insulation are obvious measures and can often result in a 30% reduction in air leakage. The result will be a tighter house that is more energy efficient, more comfortable, fewer drafts and often healthier. Blower door tests will also indicate if any installed HVAC (heating, ventilation and air conditioning) system is functioning correctly. Duct systems can contribute significantly to air leakage problems. * All buildings need a required amount of ventilation to ensure that the occupants are not affected by sick building syndrome. Houses that are very tight will require mechanical ventilation with heat recovery (for energy efficiency) to maintain a healthy environment for the occupants. Download Blower Door Information Sheet PDF file. |
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