137. When the temperature of the exhaust air does not exceed 30 ºC, the sensible heat content of the exhaust air in kilowatts shall be calculated by using the formula:
Cs: 0.00123 Q (te - to)
Cs: sensible heat content in kW
Q: rated capacity of the building exhaust air system at normal exhaust air temperature in L/s
te: temperature of the exhaust air before passing through any heat recovery apparatus in ºC
to: outdoor design temperature for heating purposes in ºC.