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adjusted so that there is no differential pressure between the middle
and the upper and lower floors there will be no cross leakage from the
middle floor. The measured air leakage rate will therefore be the
envelope leakage for that floor.
Some example good practice target values (at 50 Pa) are
[3]:
Air-conditioned offices
5 m
3
m
-2
h
-1
Naturally Ventilated offices
10 m
3
m
-2
h
-1
Superstores
5 m
3
m
-2
h
-1
The measured values quoted are the arithmetic mean of the air
leakage rates measured for pressurisation and depressurisation tests.
It follows that the air leakage rate measured under unbalanced
conditions will be an over estimate of the air leakage through the
envelope by an amount depending on the degree of leakage to
neighbouring units.
3
Bahnfleth W P, Yuill G K, Lee B W. Protocol for Field Testing of Tall Buildings to Determine Air Leakage Rate.
ASHRAE Transactions. 1999. pp27-38.