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  • Writer's pictureS.Samson

The Airtight Revolution: The Future of Sustainable Building in Australia

Updated: Sep 12, 2023

If you're interested in sustainable building, you may have heard of a "Blower Door Test" before. Testing a home's airtightness with a blower door is like taking a Ferrari to the track - you want to know if it performs like a well-oiled machine or if it's leaking air like a rusty old jalopy. Just like a supercar needs to pass rigorous performance and safety tests to deliver maximum power and speed, a home needs to be airtight to achieve maximum energy efficiency, comfort and reduce condensation.


What is a Blower Door Test?

A Blower Door Test is a diagnostic tool used to measure the airtightness of a home. It's performed by a trained professional using a specialized piece of equipment called a Blower Door. The Blower Door is essentially a large fan that is mounted in the doorway of the home. Once it's turned on, the fan pulls air out of the home (and/ or pushes it in), which causes air from the outside to be drawn into the home through any leaks or cracks.

As the Blower Door creates negative pressure in the home, the technician can use a device called a manometer to measure the pressure difference between the inside and outside of the home. This information can then be used to calculate the air infiltration rate of the home using the internal volume (m3/hr.m3 at 50Pa) or total surface area of the envelope (m3/hr.m2 at 50Pa). The results of the Blower Door Test can provide valuable information about the overall airtightness of the home and identify areas where air leaks are present.


Why is it important to have an airtight home?

There are several reasons why it's important to have an airtight home. First and foremost, an airtight home is more energy-efficient. When a home is not airtight, air can leak in and out of the home. This leakage is called thermal bypass where hot or cold air has an easy path to bypass the insulation layer, causing the heating and cooling system to work harder than necessary to maintain a comfortable temperature. This can result in higher energy bills and can put unnecessary strain on your HVAC system.

In addition to saving energy, an airtight home can also improve indoor air quality. When outside air is allowed to enter the home through leaks and cracks, it can bring with it dust, allergens, interstitial condensation and pollutants. An airtight home, on the other hand, will help keep contaminants out, reduce condensation and improve the overall health and comfort of those living in the home.

Finally, an airtight home is often a more comfortable home. When air leaks are present, it can create drafts and cold spots in the home. By sealing up these leaks, you can create a more consistent and comfortable indoor environment that is completely within your control.


Airtightness in Australia

In Australia, the National Construction Code (NCC) has recently introduced (2019) a new air-tightness requirement for residential homes. Compliance with P2.6.1 (f) requires that a building envelope be sealed at an air permeability of not more than 10 m3/hr.m2 at 50Pa of pressure when tested in accordance with AS/NZS ISO 9972 Method 1. This means that homes must be sealed tightly enough to limit the amount of air that can leak in and out of the building, ensuring that energy is not wasted on heating or cooling unused spaces. Part 3.12.3 of the NCC also requires the sealing of windows and lights to comply with these regulations.

While this verification process is not yet mandatory, it is a step in the right direction towards promoting energy-efficient and sustainable living. As the world continues to grapple with the effects of climate change, it is becoming increasingly clear that we must take action to reduce our carbon footprint. By sealing our homes more tightly and reducing energy waste, we can do our part to help protect the planet while also saving money on energy bills.


How is it used in a Passivehaus?

A Passivehaus is a type of ultra-energy-efficient building that is designed to be as airtight as possible. In order to achieve this level of airtightness, a Blower Door Test is should be performed during the build, usually before internal linings are installed, and must be performed at the end of the construction process. The test is used to identify any areas where air leaks are present and to verify that the building meets the rigorous airtightness standards of the Passivehaus institute.

During the construction of a Passivehaus, special attention is paid to the building envelope. The envelope includes the walls, roof, and floor of the home and is intended to be as airtight as possible. This is achieved through planning and design, high quality windows and doors, and careful attention to detail during the construction process.

Once the home is complete, a Blower Door Test is performed to verify that the home meets the Passivehaus airtightness standards of 0.6 ACH @ 50pa to ATTMA TSL4. If the test reveals any leaks, they must be sealed up before the home can be certified as a Passivehaus.


Who is ATTMA?

ATTMA is the Air Tightness Testing and Measurement Association, a UK-based organization that sets the standards for Blower Door Testing and airtightness measurement. ATTMA was formed in 2002 and has since become the leading organization in the UK and Australia, among other countries, for air tightness testing and measurement.

ATTMA provides training and certification for Blower Door Test technicians and sets the standards for airtightness testing in Australia.



Speaking of Blower Door Testing and airtightness, if you're in need of a company that specializes in these areas, look no further than SUSTAINABUILDING! Our team of experts are dedicated to helping homeowners and builders achieve maximum energy efficiency, indoor air quality, and comfort through the use of Blower Door Testing and airtightness solutions. We are trained and certified by ATTMA to perform Blower Door Tests and identify areas of air leakage in homes and buildings. With our state-of-the-art equipment and years of experience, we can provide accurate and reliable results to help you make the most of your home or building.


Image: Airtightness being implemented at the SUSTAINABUILDING demonstration home.


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