Q: Airtight? A: Blower Door Testing

Category: Energy Efficiency

Energy Efficiency – Airtight Testing

White House warm air arrows escaping With energy prices rising year on year, this alone is a good reason to check any homes air tightness. However, there are other reasons – some which can seriously affect health, which make it important to test airflow.

At one time or another, everyone has lived in a house that seems impossible to warm in the winter and becomes unbearably warm in the summer. An invisible problem, air leakage can present major problems aside from an overly warm or cold home. Losing large amounts of warm air to the outside means sharp rises in heating costs, cause damp and condensation issues, as well as making for uncomfortable living conditions for residents. 

Have you been offered a Blower Door Test as part of the Green Deal?

Blower door testing makes it easy to identify just where air leakage is occurring, giving a clear view of the worst spots and making sure qualified builders can plug those leaks.

What is Blower Door Testing? 

Detecting escaping air, because it can escape from multiple, hidden spots, requires a rigorous detection method that makes it easy to see problem areas. This is exactly what blower door testing delivers.

The basic components of a blower door test consist of; an adjustable, flexible panel and frame which slide into the space an exterior door occupies, a powerful, adjustable fan, a manometer and hoses for evaluating airflow, and air pressure gauges for the interior and exterior of the house.

The fan sucks the air inside the house out, making the pressure inside much lower, otherwise known as depressurisation – whilst pressure can vary due to outside conditions, the pressure is usually around 50 pascals. This magnifies any leaks the building might have, making it much easier to identify and treat them.

The pressure gauge attached to the blower door makes it easy to measure the airflow needed to keep the pressure differential between the outside and inside at the right level.

In some cases, the auditor will take several readings, altering the pressures involved, then adjust for temperature and take an average reading of all of the tests. This enables the auditor to build the most accurate model possible of airflow and the overall leakage area of the house.

It also common practice with some auditors to integrate thermographic scans into their tests. As the blower door emphasises air leaking from the building, the auditor can use a hand-held thermographic camera to see the leak of heat from a building, which appears as black streaks emanating from the building.

  • Blower door testing uses a powerful fan, adjustable door frame and panel, pressure gauges, a manometer and hoses and, sometimes, a thermographic camera
  • The fan sucks air from the house, lowering the pressure inside, which magnifies any airflow leaks
  • The auditor can then use the manometer, thermographic camera and other tools to identify the leaks and the amount of airflow present

Fresh Air

Homes that leak air, because there is no way to regulate the flow, do not provide a healthy, constant amount of fresh air. For example, when the weather outside is bitterly cold and windy, that air will infiltrate the house, but is unwanted. However, when the weather is hot, humid and there is little to no wind, the air inside the house is likely to remain uncirculated and stale.

Condensation, Mould and Rot

Another factor to consider with air leakage is how it can lead to, and spread, condensation and mould. Because many areas that leak air are hard to identify or hidden, condensation can build over time, eventually leading to mould and even rot. Mould spores in the air can have an extremely detrimental effect on health. At the same time, rot can eat away, unchecked, at roof timbres and other areas, causing large amounts of costly damage.

Energy and the Environment

Homes that are as protected against air leakage as possible use much less energy for heating than those that are not.

Because a blower door tested house retains its heat much more efficiently, that means less energy expenditure for the occupants and lower bills.

At the same time, the house that uses less energy is much kinder to the environment, whereas a house leaking air requires near-constant heating to keep interior temperatures at a pleasant level. With the environment becoming an increasingly important issue, homes that use energy as efficiently as possible are going to become more and more desirable.