(1) Total surface area of enclosure (S)
W 1000 mm x H 2000 mm x d 600 mm
S = 7 m2 (except the bottom)
(2) Estimated total amount of heat produced in the enclosure (P)
P = 500 W
To make the internal temperature setting lower than the maximum ambient temperature.
(1) Maximum ambient temperature (T1)
T1 = 40 °C
(2) Temperature setting inside the enclosure (T2)
T2 = 35 °C
หมายเหตุ : Sheet steel, free standing
 Heat transition coefficient of the enclosure (U)
U = 5 W / (m^{2}.K)

 Difference between (T) the temperature setting inside the enclosure(T_{1}) and
maximum ambient temperature (T_{2})
T = T_{1}  T_{2} = 5 °C
The above values are used to obtain the amount of heat transmitted from the
outside into the enclosure (P_{1})
P_{1} = U x S x T
= 5 x 7 x 5
= 175 W
The minimum cooling output (P_{T}) required for this case
P_{T} = P + P_{1}
= 500 + 175
= 675 W
Select a model whose cooling output in higher than the required cooling output (P_{T}) 