Does warm air heating use less energy than radiant heating? A clear answer

Abstract

The paper shows that the two temperature ratios F₁ and F₂, introduced in section A9(1979) of the C.I.B.S. Guide to calculate steady state heat loss coefficients as function of the proportion of radiant heat to be supplied, are not independent, in that 3F₁ + F₂ = 4. From this it follows that if for a building or room ≥ AU < NV, the heat loss coefficient for any method of heating containing a significant proportion of radiation is smaller than that for warm air heating, for the same dry resultant temperature. This is confirmed by examples. The result is applied to factories built to satisfy part FF of the Building Regulations, and it is shown that only for small factories with little ventilation will the heat loss coefficient for warm air heating be less than for heating including radiation.