Infiltration or air leakage can have a significant impact on the required heat load for a house and in some cases can have a bigger impact than insulation values. This shows up in both energy modeling and in actual retrofit improvements to existing homes. (see below for FAQ on infiltration)
There are 5 equally important items that are required to achieve successful results to minimize air leakage:
1) An initial infiltration and ventilation strategy: It’s not only important to have a plan to minimize air leakage in a house, it’s equally important to have a strategy to bring in fresh air and exhaust stale air in a house (ventilation will be the next blog post).
2) Material selection
3) Installation and construction techniques and process
4) Training and / or experience
5) Attention to detail and mindset to do it right and take pride in the work being done
After window and cellulose installation and air sealing at CreekSide Net Zero, we achieved an infiltration rate of 0.28ACH50 which is 53% lower than the Passive House Institute target and 15% lower than our initial blower door test which was conducted earlier in the process.
It is truly an example of excellent collaboration, communication, coordination and attention to detail. There were 3 companies that worked together to achieve this excellent result:
– New Energy Works who were responsible for the pre-panelized double wall and roof I-beam construction and installation, exterior zip wall and interior zip ceiling air sealing as well as the window installation
– Airtight Services who were responsible for the cellulose insulation installation and window foam
– CreekSide Energy Solutions who were responsible for window, door and other envelope penetration air sealing
All of these companies have a ‘do it right’ culture that sets them apart from other contractors and construction companies.
Why test for infiltration? All other factors being equal, a leaky house will have a significantly higher heat loss than a tight house.
How to test infiltration? A calibrated blower door assembly with a fan and manometer is mounted in a doorway and the fan either blows air out of or into the house to either depressurize or pressurize the house. The manometer will control the fan speed to meet required pressure and also provide a readout of the infiltration rate. Either a smoke stick or infrared camera can then be used to identify leaky areas.
How is infiltration rate measured? XACH50 = X air changes per hour at 50 pascals based on the volume of the house, 50 pascals is approximately equivalent to a 20 mph wind blowing on all faces of the house being tested.
What is the infiltration rate target for an Energy Star house? 4ACH50 for climate zone 5 (Pulaski, NY)
What is the Passive House infiltration rate target? 0.6ACH50 (A high bar set by the Passive House Institute to meet their stringent criteria, and a good indicator of performance)