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What is air leakage & what impact does it have?
Building air leakage & energy efficiency
We use fan pressurisation testing of buildings to
show compliance with Part L of the Building Regulations.
Pressurisation testing equipment ranges from single and
multiple fan units, to large truck mounted fan
systems. The following table shows recommended air
leakage specifications for different building types.
|
Air Leakage Index (m3/hr/
m2 @ 50Pa) |
| Building Type |
Best Practice |
Normal |
| Offices (naturally
ventilated) |
3.0 |
7.0 |
| Offices (mixed mode) |
2.5 |
5.0 |
| Offices (air
conditioned/low energy) |
2.0 |
5.0 |
| Factories/Warehouses |
2.0 |
6.0 |
| Superstores |
1.0 |
5.0 |
| Schools |
3.0 |
9.0 |
| Hospitals |
5.0 |
9.0 |
| Museums and Archival Stores |
1.0 |
1.5 |
| Cold Stores |
0.2 |
0.35 |
| Dwellings (naturally
ventilated) |
3.0 |
9.0 |
| Dwellings (mechanically
ventilated) |
3.0 |
5.0 |
The air leakage test involves connecting the fans to a
suitable aperture in the building envelope, usually a
double door opening. The fans are variable speed and
therefore variable volume.
With the test rig connected to the building the pressure
will be increased in 5.0 Pa increments from 10.0 Pa to
60 Pa or the maximum that can be achieved. Then 5.0 Pa
decrements down to 10 Pa. At the time of the tests the
barometric pressure is recorded as well as the internal
and external temperatures.
All the logged readings are used to calculate the air
leakage rate at 50 Pa standard atmosphere. Should the
building pass then a witness certificate must be signed
by the builders representative.
It is anticipated that the work can be carried out in
one day. We will only require the building to be free of
personnel for a period of approximately1.0 hour at any
one time.
The local wind speed should preferably be below 3.0m/s.
Before the test is carried out, all mechanical
ventilation systems must be switched off.
All extract and supply terminals need to be sealed of
with plywood sheeting or plastic sheeting and gaffer
tape.
Trickle vents and smoke vents must be closed but not
sealed
Drain traps should be filled.
All internal doors wedged open to equalise the internal
pressure.
Opening windows and external doors must be shut.
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