Did you know that as well as being an acoustic consultancy, we are an ATTMA Registered Air Tightness Testing company with Level 1 and Level 2 testers?
What is Air Tightness?
Air tightness testing, sometimes called an ‘air leakage test’ is way to establish just that. How much air is leaking through a building. Air leakage is essentially the uncontrolled flow of air through gaps and cracks in the fabric of the building. There are two categories of air in a building, ventilation and infiltration. While ventilation is meant to be there, infiltration is not. The air tightness test is designed to measure the infiltration and gives us an idea of how much infiltrating air is present and, if possible, where it is coming from.
Why Test?
All new builds in England & Wales must be tested to comply with either Approved Document L Volume 1&2 2021 (as amended 2023) or the older version, L1A or L1B 2010. Older buildings may still fall under L1A depending on commencement date.
Approved Document L 2021 (amended 2023):
- Part L Volume 1 – domestic
- Part L Volume 2 – non-domestic
Approved Document L 2010:
- Part L1A – domestic
- Part L1B – non domestic
There are different standards for Northen Ireland (Technical Booklet 2012 F1) and another for Scotland (Section 6 Technical Handbook 2019).
Regulations are not the only reason to test of course. Infiltration can have a number of detrimental effects of a building and its occupants such as:
- Larger U-Values
- Heating or cooling systems unable to meet demands
- Increased energy usage
- Draughts
- External contaminants entering a building
- Increased sound transmission from external sources
In worst case scenarios air leakage can also degrade the fabric of the building over time, resulting in the need for expensive repairs.
A building should be tested as close to completion as possible. There is no point testing if the building is incomplete.
What does a test do?
Air tightness tests use a fan, temporary sealing, thermometers, barometers and some mathematics to work out how much air leakage a building has.
A test will:
- Calculate the air permeability
- Calculate the air flow exponent
Create a coefficient of determination.
What happens during a test?
A tester will take measurements from the building plans to work out its internal envelope and volume. Once they know how big the building is internally, the internal/external temperature and barometric readings are taken. The ventilation is temporarily sealed, and a fan is placed in an appropriate external door within a frame. Pre-test zero or ‘static’ flow pressures are taken, then the fan is turned on to either pressurise or depressurise the building. The tester will take a series of flow readings which measure the air as the fan runs. Once complied and post-test zero flow pressures are taken, we will be given information which tells us how the building has performed. A tester will then check the results to see if they meet or exceed the relevant regulations for the building and the design air permeability given to it by the SAP or SBEM report.
