Boiler Fuel Switch CO2 and Cost Calculator
Boiler fuel and efficiency decide both your energy bill and a large part of your Scope 1 emissions. This calculator compares a current boiler with a replacement fuel and efficiency, giving fuel use, CO2 and money side by side.
Your numbers
Steam or hot water energy leaving the boiler, not fuel input.
Your results
Factors are CO2 only, from US EPA emission factor tables. CH4 and N2O add a small amount. Use your jurisdiction's official factors for reporting.
Annual fuel saving vs new fuel price
Sweeps New fuel price from 2 to 40, holding your other inputs fixed.
Need Scope 1 data from your ERP?
Optional expert review of connecting fuel purchases to an emissions inventory.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Estimate useful heat from steam or hot water meters, or back-calculate from last year's fuel use times the boiler efficiency. Choose the current fuel, enter its efficiency and delivered price per MMBtu, then do the same for the new fuel or new boiler. For a pure efficiency upgrade, keep the same fuel on both sides. The tool returns fuel input, combustion CO2, the reduction and the annual cost saving. Sweep the new fuel price to test gas market volatility.
- Use delivered price including demand and delivery charges
- Convert gallons or therms to MMBtu before entering prices
- Confirm efficiency with a combustion test, not nameplate
The formula
Fuel input equals useful heat divided by efficiency. Combustion CO2 in tonnes equals fuel input in MMBtu times the emission factor in kg per MMBtu divided by 1000. Typical US EPA factors are about 53.06 for natural gas, 62.87 for propane, 73.96 for distillate oil, 75.10 for residual oil and 93.28 for bituminous coal. Cost saving is current fuel input times current price minus new fuel input times new price.
Reading the result
Going from 78% efficient oil to 88% efficient gas, as in the defaults, cuts fuel input by about 11% and CO2 by around 36% because gas carries less carbon per unit of energy. The chart shows the saving shrinking as the new fuel price rises, and you can read off the break-even price. Add capital cost and conversion work outside this tool to get payback. Electrification options such as heat pumps need a different model based on coefficient of performance.
Common mistakes
A frequent error is comparing fuel prices per gallon and per therm without converting to a common energy unit. Another is ignoring that biogenic CO2 is reported separately rather than counted as zero emissions overall. Upstream methane leakage is not included in combustion factors. Keep fuel purchases, meter readings and emission factors with versions in your energy or ERP records so the inventory is traceable.
- Convert to MMBtu first
- Use higher heating value consistently
- Document factor source and year
Frequently Asked Questions
What emission factor does natural gas use?
The US EPA lists about 53.06 kg CO2 per MMBtu for pipeline natural gas. That is combustion CO2 only. Reporting frameworks may also require CH4 and N2O, using the factors for your jurisdiction and reporting year.
Is switching from oil to gas always cheaper?
Not always. It depends on the delivered price per MMBtu of each fuel and on efficiency. Use the sweep chart to find the price at which savings vanish, and add conversion capital to get payback.
How do I get useful heat?
Use a steam or BTU meter if you have one. Otherwise multiply annual fuel input by measured boiler efficiency. Avoid nameplate efficiency, which can be several points higher than the in-service value.
Why is biomass shown as zero?
Under common inventory rules, biogenic CO2 is reported outside the Scope 1 total, while CH4 and N2O from burning biomass are still counted. The option is shown for comparison. Check your protocol for the treatment you must use.
Netray can link fuel purchase orders, meter readings and boiler maintenance records in your ERP to a Scope 1 view you can query, on premise if needed.
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