How do I calculate emissions from a thermic fluid heater?
Calculate them from the fuel the heater burns, not from the hot oil it circulates: fuel quantity times the fuel's emission factor gives Scope 1 CO2. An electric thermic fluid heater has no Scope 1; its kWh go into Scope 2 at the grid factor.
Factors for the usual fuels
Take the quantity from fuel invoices, adjusted for stock at the start and end of the year.
- Coal: 2.42 kg CO2 per kg (IPCC 2006 based default; real coal varies by grade).
- Furnace oil: 2.97 kg CO2 per litre.
- PNG: 2.05 kg CO2 per standard cubic metre.
- Diesel or LDO: 2.68 kg CO2 per litre for diesel.
- Wood, briquettes or husk: the CO2 is biogenic and reported separately; only methane and nitrous oxide count in Scope 1.
When the heater shares fuel with a boiler
If one coal yard or one gas meter feeds both a steam boiler and a thermic fluid heater, the total Scope 1 is the same either way. Split it only if you need emissions per unit or per product. Use separate gas sub-meters, coal weighment per day, or the heat duty method below to share the fuel.
Estimating fuel from heat duty
Fuel used = heat delivered / (fuel calorific value x heater efficiency). Heat delivered is the heater's rated kcal per hour x average load x hours run. Use the gross calorific value on your coal test report or supplier bill, and a measured efficiency if you have one; thermic fluid heaters often run at about 75 to 85 percent. Treat the result as an estimate and reconcile it with purchases.
What does not count as combustion
- Thermic fluid top-ups: the oil is not burnt, so it adds no combustion emissions. It is a purchased material for Scope 3.
- Spent thermic fluid sent for disposal: a hazardous waste stream for Scope 3, not Scope 1, unless you burn it on site.
- Electricity for the circulation pumps: Scope 2.
Worked example: one month for a coal-fired heater
- Rating 10,00,000 kcal/h; average load 60%; 500 hours run
- Heat delivered: 10,00,000 x 0.6 x 500 = 30,00,00,000 kcal
- Coal GCV 4,000 kcal/kg, efficiency 75%: 30,00,00,000 / (4,000 x 0.75) = 1,00,000 kg coal
- Scope 1: 1,00,000 x 2.42 = 2,42,000 kg CO2, about 242 t
- Check: coal received minus stock change in the month should be close to 100 t
The calorific value and efficiency are illustrative. Use your coal test report and a measured efficiency; the coal invoices remain the primary evidence.
What Senseible does here
Senseible reads coal, wood, furnace oil, PNG and diesel invoices as Scope 1 at IPCC 2006 defaults, and electricity bills as Scope 2 for electric heaters. A heat duty estimate is your own working, kept beside those invoices.
Sources: 2006 IPCC Guidelines, Volume 2 Energy, Chapter 2 (stationary combustion), BEE Energy Auditor Guide Book 2, Energy efficiency in thermal utilities (fuels, combustion, efficiency), GHG Protocol Corporate Standard
Last reviewed 2026-10-18.