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BTU to kW metric conversion formula

BTUs to kWs Table Converter

BTUs (British Thermal Units)kWs (Kilowatts)
3000 BTUs0.88 kWs
5000 BTUs1.47 kWs
6000 BTUs1.75 kWs
7000 BTUs2.05 kWs
8000 BTUs2.34 kWs
9000 BTUs2.63 kWs
10000 BTUs2.93 kWs
11000 BTUs3.22 kWs
12000 BTUs3.51 kWs
13000 BTUs3.80 kWs
14000 BTUs4.10 kWs
15000 BTUs4.39 kWs
16000 BTUs4.68 kWs
17000 BTUs4.98 kWs

To calculate BTU’s transferred to the other side of the roof you need to know also Thermal resistance of the roof assembly (R).

  • 3412.142 BTU hours = 1 kW hour
  • 1000 BTUs = 0.293 kW
  • 1 kW = 1000 watts

The formula looks like this:

(T1 – T2)/ R or if R = (R1+R2+R3+R4…Rn) formula looks like this: (T1- T2)/ (R1+R2+R3+R4…Rn);

Formula is in the American (Imperial) units so all data we need to transform to American units:

  • 40C=104F; current roof temperature
  • 30C=86F; reduced roof temperature with Super Therm
  • 25C=77F; ambient air temperature
  • 3,000m2=32,290ft2; area of the envelope of building
  • R=11.18BTU/hr ft2 F; R-value for the roof could be any (assuming insulation installed)

So, here are the results for a heat transferred with the data entered:

(104F-86F)/11.18BTU/hr ft2 F = 1.61BTU/hr ft2;

For 32,292ft2 roof: 1.61BTU/hr ft2 F * 32,292ft2 = 51,990.12 BTU/hr;

51,990BTU/hr = 15.24 kW;

kW per m2 is 15.24 kW/3000m2=0.0051kW/m2.

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