Fuel cost and displaced-fuel savings calculator

The warehouse example divides by heater efficiency; do not double-count it for fuel-basis savings.

Units

S_{f} = \frac{Q_{\text{displaced}} \times c_{f}}{\eta_{\text{displaced}}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

S_{f} = \frac{350{,}000{,}000 \times 0.000014}{0.82} \approx 5{,}976

Symbol	Meaning	Unit
$S_{f}$	annual displaced-fuel cost	$/yr
$Q_{\text{displaced}}$	useful heat that replaces purchased heating	Btu/yr
$c_{f}$	fuel energy price	$/Btu
$\eta_{\text{displaced}}$	efficiency of displaced heater; 1 if Q is already fuel input	fraction

Symbol	Meaning	Unit
$S_{f}$	annual displaced-fuel cost	$/yr
$Q_{\text{displaced}}$	useful heat that replaces purchased heating	kWh/year
$c_{f}$	fuel-energy price per kilowatt-hour	$/kWh
$\eta_{\text{displaced}}$	efficiency of displaced heater	fraction

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.