Heating & gas calculators
Gas, oil, wood and heat-pump heating costs, boilers, gas unit conversions.
Heat pump running cost
Models an air-source heat pump month by month for your climate: heat demand, COP at every outdoor temperature and flow temperature, electricity use, running cost versus your current boiler and CO₂ saved.
Heating & gasHeating cost comparison
Ranks nine heating systems (gas, LPG, oil, electric, air- and ground-source heat pumps, pellets, logs and district heating) by cost per kWh of useful heat, annual bill and CO₂, using your own prices.
Heating & gasHeat pump vs gas boiler
Compares an air-source heat pump with a new condensing gas boiler on running cost, installation, maintenance, standing charges and CO₂, and shows the electricity-to-gas price ratio at which they break even.
Heating & gasGas bill from meter reading
Turns two gas meter readings (m³, ft³, kWh or therms) into kWh using the calorific value and volume correction exactly as suppliers do, then adds unit price, standing charge and VAT. It also estimates your annual gas use from a single bill.
Heating & gasInsulation savings
Enter the area and U-value of walls, roof, windows and floor before and after insulating. Using heating degree days for your climate, it shows the heat loss avoided, kWh and money saved, CO₂ and payback for each measure.
Heating & gasGround source heat pump
Sizes a ground-source heat pump from your heat demand: kW output, borehole metres or horizontal collector area for your soil or rock (VDI 4640 extraction rates), seasonal COP, running cost and installed cost versus an air-source unit and gas.
Heating & gasGenerator fuel consumption
How much diesel, petrol, LPG or natural gas a generator burns at any load, how long a tank lasts and what each kWh really costs once engine wear is counted, compared with grid power and solar plus battery.
Heating & gasBiomass boiler fuel & cost
From your annual heat demand to tonnes and cubic metres of logs, chips or pellets (corrected for moisture content), plus boiler size, buffer tank, store volume and the running cost against gas, oil and a heat pump.