What is Airtightness in a Home?
One of the most important, and often overlooked, aspects of a home’s energy performance is the airtightness of
the home. Builders often forget that a home’s energy performance can be improved significantly by ensuring that it
is airtight before, during and after it is built.
This can be achieved through careful design for airtightness and the use of high-quality construction materials such as Insulated Concrete Forms.
What is Airtightness?
Airtightness is the measurement of how well a building limits air movement into and out of the structure. It is important because it controls the amount of outside air that can enter and exit a home, which affects the energy use, comfort, indoor air quality, and durability of the building.
Why is Air Tightness important?
Airtightness is one of the most important aspects to consider when creating an energy efficient home. That is why modern materials like SIPs and ICF are becoming more popular. However, you can also upgrade an older home by increasing the overall insulation in the wall cavities with a special focus on wall seams, door and window openings.
How to measure and test the airtightness of your home
A variety of airtightness test methods can be used to assess the airtightness of a property. The most popular method for both new builds and existing properties is the fan pressurization, also known as the ‘blower door’ test. This method can accurately measure the rate of air leakage throughout the entire building envelope.
What is a Building Envelope:
the parts of the building that separate the interior and exterior of a building. The envelope typically consists
of the roof, walls, door and window openings and the foundation.
It is a vital part of a building’s thermal performance and overall build quality. The envelope is what helps maintain indoor temperatures, minimize heat loss and protect the home from harsh weather, noise and pollution.
How is a blower door test done?
To test the airtightness of a home, the house is sealed up as much as possible and then a powerful fan is mounted in an external door frame. There are two ways this test can be performed, the fan is set up to either pull or push the air inside the home in order to depressurize or pressurize the inside of the house. Sensors then measure the movement of air and calculate how much airflow / pressure is created. This process takes anywhere between 1-3 hours depending on the size of the home.
When to Test Airtightness?
For a new construction build, the ideal time to test for airtightness is right before any internal finishes such
as plasterboard or cement board are applied. This will ensure that you can properly seal and air gaps or cracks in
your home before you finish the interior or exterior elements.
When renovating an older home, you are still able to improve your airtightness by installing draught-proofing strips around doors and windows or even adding extra layers of seal or caulking in areas where it is missing.
You can always try to perform a thermal imaging inspection of your home to try to identify any temperature drops. This can be a good indicator of air permeability or and air gaps in the building envelope.