Energy & Insulation Calculators

UK home energy and insulation calculators — radiator BTU heat-loss sizing (with heat-pump ΔT30 correction), air-conditioning sizing, and loft, floor and wall insulation quantities to current Building Regulations. Size heating and insulation correctly and estimate running costs.

Energy
Radiator BTU Calculator
Room heat loss using the CIBSE method with radiator sizing and ASHP correction factor.
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Energy
Air Conditioner Calculator
AC cooling sizing in BTU, kW and tons, with efficiency and UK running costs.
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Energy
Loft Insulation Calculator
Rolls needed to reach the recommended 270mm depth to current Building Regs.
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Energy
Loft Flooring Calculator
Chipboard panels and loft legs needed to board a loft over insulation.
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Energy
Floor Insulation Calculator
PIR boards or mineral wool for suspended or solid ground floors.
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Energy
Wall Insulation Calculator
Insulated plasterboard or stud-and-slab quantities for internal wall lining.
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How these calculators work

Heating and insulation only work when they're sized correctly. The radiator BTU calculator estimates room heat loss using the CIBSE method and applies a heat-pump correction (ΔT30) so a radiator sized for a gas boiler isn't left undersized on a heat pump. Insulation tools work to current Building Regulations depths — such as 270mm for loft insulation — and the air-conditioning tool sizes cooling in BTU, kW and tons with UK running-cost estimates.