Annex Classes of performance in relation to air permeability for roof lights of plastics and glass and roof hatches

United Kingdom

Class	Lower limit value of Internal Pressure(4 Pa)	Higher limit value of Internal Pressure(100 Pa)
In case of class A, in addition to declaring the class, the worst measurement of all pressure steps shall also be declared using the following template: Class A (internal pressure (100Pa), assessed leakage rate).
Note: The boundaries of the classes used in this Table may be derived from the following formula: $Q = Q_{100} \times {(\frac{P}{100})}^{2 ∕ 3}$ Where: Q is the leakage rate in m³ per hour, per linear m rooflight perimeter during a test under internal pressure P is the internal pressure during a test (in Pa) Q₁₀₀ is the leakage rate in m³ per hour, per linear m rooflight perimeter at an internal pressure of 100 Pa
Class	Air permeability(in m³/(h.m))
A^f1	< 1,4	< 12
B	≥ 1,4	≥ 12
C	≥ 6	≥ 50

Annotations

f1: In case of class A, in addition to declaring the class, the worst measurement of all pressure steps shall also be declared using the following template: Class A (internal pressure (100Pa), assessed leakage rate).