Blower Door Test, Setup and Results
One aspect of an Energy Star certified home is the airtight-ness of the structure or thermal envelope. We all know that heating and cooling your home accounts for the bulk of your monthly utility bill and that’s why minimizing air infiltration is so important.
Air leaks can have a huge impact, negating triple pane windows or excellent insulation. They occur in many different places like doors, window frames, outlets, fireplace dampers and attic entries. Blower door tests reveal these problems so you can take the right steps to “button up” your home.
Calibrated blower door tests are an important part of a home energy audit- the best way to understand the energy needs of your home.
Blower Door Test Setup
A blower door test has two main pieces of equipment- the door and the pressure sensor. This test starts by setting up an adjustable, canvas door with an integrated fan that effectively seals off an exterior entrance. The fan is used to equally depressurize the entire home making air leaks more prominent, and the sensor is used to determine the difference between the fan flow and building pressure. The fewer the air leaks, the less the fan works to maintain that pressure.
Understanding Blower Door Test Results
The blower door fan works to depressurize your home to 50 pascals. A CFM50 score (cubic feet per minute) is determined by how much air flow is required to achieve that pressure difference between the inside and outside of the home. These results are normalized for better comparison. The CFM50 measure, combined with the total volume of the house, can be used to compute the air changes per hour (ACH), and at 50 pascals, you get the ACH50 score. An ACH50 score of 5 or less indicates a tight house. A score between 5 and 10 indicates a moderately tight house and anything above indicates a leaky house.
How Blower Door Result are Used
The results of a blower door test are used for a Home Energy Rating Score (HERS) and to earn the Energy Star certification.
HERS A HERS compares your home to the HERS reference home and, ultimately, to other homes. The index ranges from 0 to 150 with lower scores indicating less energy (more efficient). The HERS index shows that standard new homes score a 100 and most existing homes score about 130. A net zero energy home receives a score of 0.
Energy Star Certification The EPA has set strict guidelines to earn Energy Star Certification, ensuring homes are 20-30% more efficient. To be eligible, a home energy rater works with the builder to implement energy-saving equipment and construction techniques. They also perform various on-site diagnostics including the blower door test.
What do you think? Have you had a home energy audit?
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