Measuring success: Using the blower door test for Net Zero standards

January 20, 2021

Throughout the construction of any residential building, there are a number of quality assurance tests that need to be done in order to achieve the Net Zero or Net Zero Ready standard. One such of these tests is a blower door test — which Big Block had Sun Ridge Residential conduct for the National Affordable Housing Corporation Willowview Heights projects. 

A blower door test measures the air leakage of a building which is then gauged against industry standards. These standards are measured in air changes per hour (ACH) and vary depending on certain certifications the builder may be going for. 

For instance, new home minimum requirements for air tightness are set at 3.2 ACH whereas the ACH for an Energy Star new home must be at 2.5 for single detached units and 3.0 for attached units. Net Zero homes have even more stringent regulations, requiring a rating of 1.5 ACH for single detached units and 2.0 for attached units.

Willowview Heights’ ACH clocked in at 0.5 ACH — exceeding the requirements for a Net Zero build by 75%.

“The blower door test is used to confirm that the finished house complies with code or energy program ACH requirements,” said Darcy Bzdel, director of technical services for Sun Ridge Residential. 

“The blower door kit is also a very valuable tool in locating and correcting excessive air leakage areas. This is especially valuable at the pre-drywall stage when these issues can be addressed very easily.”

A blower door test is completed by setting up a fan assembly in one of the exterior doors, simulating a closed door. The fan is then used to blow interior air to the outside, creating negative pressure inside the home.

“Through a series of data points of measured house pressure (the difference between pressure inside the home and ambient pressure) and fan pressure or flow rate, the house ACH is determined,” Bzdel said.

Ensuring a home is as air tight as can be is crucial in building to Net Zero standards as it means less heat will be lost to the outdoors — and thus less energy needs to be put into heating. 

Not only does this mean a lower ACH leads to less energy consumption but tenants can be assured that the temperature of the house is less likely to fluctuate. 

Bzdel said the Net Zero Homes program aims to reduce the energy consumption of the house to 0 on an annual basis, which is done by minimizing the energy consumption of the house — increasing insulation, improving window specifications, better mechanical equipment and minimizing heat loss due to air leakage.  

“This consumption can then be offset with the installation of photovoltaic panels (or wind turbine) on-site,” Bzdel said.

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