The requirements of an air-conditioning system as laid down in BCAR’s are described below.
Provision of fresh air
Fresh air must be provided at a rate of 1 lb per seat per minute in normal circumstances, or at
not less than 0.5 lb following a failure of any part of the duplicated air-conditioning system
(No JAR Figures quoted except for crew which is “not less than 10 cubic ft per minute per crew
member”)
Temperature
Cabin air temperature should be maintained within the range 65°F to 75°F, (18°C to 24°C).
Relative humidity
The relative humidity of the cabin air must be maintained at approximately 30% (at 40,000 ft the
relative humidity is only 1 to 2%).
THIS EXCERPT STATES OTHERWISE AND IS WHY I ASK...IT'D BE GREAT IF SOMEONE FLYING THE BRITISH SKIES COULD CLEAR THIS UP...!!