Calculators › Benchmarking, budgets and carbon Heat-pump carbon break-even grid factor calculator
Heat-pump carbon break-even grid factor
Compare fuel and grid emissions for equal useful heating service. The break-even factor includes boiler losses and heat-pump COP; 3412 converts kWh to Btu on this approximation.
Units IP (US) SI (metric)
E F grid,max = E F fuel × 3412 × C O P × 100 1 , 000 , 000 × η b \mathrm{EF}_{\text{grid,max}} = \frac{\mathrm{EF}_{\text{fuel}} \times 3412 \times \mathrm{COP} \times 100}{1{,}000{,}000 \times \eta_{b}} EF grid,max = 1 , 000 , 000 × η b EF fuel × 3412 × COP × 100 E F grid,max = E F fuel × 0.0036 × C O P × 100 η b \mathrm{EF}_{\text{grid,max}} = \frac{\mathrm{EF}_{\text{fuel}} \times 0.0036 \times \mathrm{COP} \times 100}{\eta_{b}} EF grid,max = η b EF fuel × 0.0036 × COP × 100
Calculator
Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.
Worked example
Given
E F fuel \mathrm{EF}_{\text{fuel}} EF fuel 117 lb CO2e/MMBtu C O P \mathrm{COP} COP 3 ratio η b \eta_{b} η b 80 % E F grid,max = 117 × 3412 × 3 × 100 1 , 000 , 000 × 80 ≈ 1.497 \mathrm{EF}_{\text{grid,max}} = \frac{117 \times 3412 \times 3 \times 100}{1{,}000{,}000 \times 80} \approx 1.497 EF grid,max = 1 , 000 , 000 × 80 117 × 3412 × 3 × 100 ≈ 1.497
Given
E F fuel \mathrm{EF}_{\text{fuel}} EF fuel 56 kg CO2e/GJ C O P \mathrm{COP} COP 3.2 ratio η b \eta_{b} η b 84 % E F grid,max = 56 × 0.0036 × 3.2 × 100 84 = 0.768 \mathrm{EF}_{\text{grid,max}} = \frac{56 \times 0.0036 \times 3.2 \times 100}{84} = 0.768 EF grid,max = 84 56 × 0.0036 × 3.2 × 100 = 0.768
Symbols and units
Symbol Meaning Unit
E F grid,max \mathrm{EF}_{\text{grid,max}} EF grid,max break-even purchased-electricity factor lb CO2e/kWh E F fuel \mathrm{EF}_{\text{fuel}} EF fuel fuel-input emissions factor lb CO2e/MMBtu C O P \mathrm{COP} COP heat-pump heating coefficient of performance ratio η b \eta_{b} η b displaced boiler useful-heat efficiency %
Symbol Meaning Unit
E F grid,max \mathrm{EF}_{\text{grid,max}} EF grid,max break-even purchased-electricity factor kg CO2e/kWh E F fuel \mathrm{EF}_{\text{fuel}} EF fuel fuel-input emissions factor kg CO2e/GJ C O P \mathrm{COP} COP heat-pump heating coefficient of performance ratio η b \eta_{b} η b displaced boiler useful-heat efficiency %
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