5. Calculations and measurements

5.1 Conditions to be met

All calculations are based on normal air conditions:

• temperature at 20 °C ;

• density of 1.2 kg/m ³ .

Smoke extraction calculations for common horizontal corridors are carried out on a compartment basis. If the compartment is made up of several levels, the calculations are carried out for all the levels, but the smoke extraction system is activated for each level under the conditions specified in article GH 49 (§ 9.1 of