HEATLOSSPROHeat loss and heat pump guides
Plain guides with the formulas, worked examples and a free calculator on every page. For installers, engineers and homeowners planning a heat pump.
How to calculate heat lossThe U × A × ΔT formula, ventilation loss, a worked example and a one-room calculator in watts and BTU.
Heat pump size from your gas or oil usageEstimate the heat loss and heat pump size of a house from last year's gas, oil or LPG consumption.
Radiator output at heat pump temperaturesHow much heat a radiator gives at 35–55 °C flow, in watts and BTU, and whether it is big enough.
U-values of walls, windows, floors and roofsTypical U-values by construction, and how to calculate one from the layers of a wall.
Heat pump running cost vs gasWhat a heat pump costs to run compared with your gas or oil boiler, from your own bills.
Heat loss per m² by house ageA quick whole-house estimate from floor area, age and type, and why it is only a first guess.
Underfloor heating output per m²How much heat underfloor heating gives by floor finish, pipe spacing and flow temperature.
Design outdoor temperatureWhich outdoor temperature to size heating for, by country and region, and what changing it does.
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