Blower Door Testing to Improve Air Tightness in Buildings

You only get one chance to put together your building envelope correctly. Once it been constructed and concealed with a plasterboard and timber, it can be very difficult to fix ultimately creating a path to a leaky home or building – that’s where blower door testing come into play. Blower door air tightness testing is now a requirement of

What is a Blower Door Testing Air Leakage Test?

So, what is blower door air leakage test? Air tightness is the amount of air that leaks through the gaps and cracks in the building envelope, which can affect the energy efficiency, comfort, and health of the occupants. Blower door equipment is used to measure the air tightness of a dwelling, commercial building, or clean room to various standards such as ATTMA TS1/TS2


What Blower Door Test Equipment is required to undertake the test?

The blower door test equipment consists of the following main components:

  • Digital manometer
  • High powered fan completes with range ring A, B, C and L flow plates
  • Aluminium door panel frame and door cloth
  • Air tightness testing software
  • Thermometer
  • Barometer

The fan is mounted on within the door panel, which is positioned in an external doorway, often the entrance door. The fan creates a pressure difference between the inside and outside of the building or room, either by blowing air in (pressurisation) or sucking air out (depressurisation). The Digital manometer measures the airflow through the fan and calculates the air leakage rate of the building envelope.


What is the Designed Air Leakage Target?

For many dwellings and commercial buildings, the designed air permeability rate may vary; however, buildings using MVHR usually need to achieve a figure below 3m3/h.m2, however, this will be stipulated within your design stage SAP (dwellings) or SBEM (commercial buildings). In our experience the most common air leakage target is 5m3/h.m2, which can still be a difficult figure to achieve.

In the event of a test failure, handheld smoke machines and the infrared cameras can be used to visually locate the sources of air leakage by detecting the smoke leakage paths and temperature differences caused by the air movement.

The reasons for Blower Door Testing

Blower door testing can be performed for various purposes, such as:

  • Checking compliance with building codes or standards that require a certain level of air tightness for new or renovated buildings.
  • Checking compliance with ISO standards that require a certain level of air tightness for cleanroom and laboratory.
  • Identifying and quantifying air leakage problems that can cause high energy bills, poor indoor air quality, moisture issues or thermal discomfort.
  • Evaluating the effectiveness of air sealing measures that aim to improve the air tightness of a building or room.
  • Comparing the performance of different buildings or rooms in terms of their air tightness.
  • Determining proper sizing and airflow requirements of heating and cooling equipment to your building.
  • Determining whether mechanical ventilation is needed to provide acceptable fresh air and maintain indoor air quality in your building.

Blower door testing is a valuable tool for many stakeholders such as developers, architects, engineers, contractors and building owners and energy auditors who want to ensure that their new and/or refurbished building envelope is well constructed and airtight which is invaluable for mechanical designers, as they can design the buildings heating/cooling system safe in the knowledge that the building fabric meets their design criteria.

So, in summary, by using blower door equipment to undertake the air tightness testing, clients can achieve higher energy efficiency, lower environmental impact and better indoor comfort and health for their buildings and occupants.

What happens if my building fails the blower door test?

If your building fails the blower door test – don’t panic! in the event of a test failure, we can undertake combined blower door Smoke testing and/or blower door thermal air leakage surveys to highlight the air leakage paths within the building fabric. This allows clients to undertake the repairs on the day to achieve a air tightness test pass, and/or in the event of a massive test failure, when can produce a detailed ‘easy to follow’ air leakage survey report to help the contractor target the main air leakage paths to improve the building envelope to achieve a pass.


We provide a professional blower door testing service

We are UKAS and ATTMA accredited to Level 2 to undertake blower door air tightness testing from the smallest dwellings to commercial buildings with floor areas in excess of 10000m2. We have undertaken blower door testing to many prestigious jobs such as The Imperial War Museum and Battersea Power Station.

We are one of the only air tightness testing companies in the UK, that provides both blower door smoke testing & thermal imaging air leakage detection in one package lowering costs and coordination issues.

If you have a project that required air tightness testing and/or air leakage surveys, please contact Darren on 07775623464 or