Estimate the heating load of a space from its area, how well it’s insulated, and the temperature difference you’re designing for — a quick kW figure to size a heater.
Rule-of-thumb estimate only. A full heat-loss calculation accounts for wall, roof, floor and glazing U-values, air infiltration and ceiling height — use a detailed method for critical jobs.
Quoting a heating install? traqR takes your sizing through to a quote, job and invoice with the equipment on the job card.
Start free trialA space loses heat through its walls, roof, floor, windows and gaps. The worse the insulation, the higher the loss per square metre.
The bigger the difference between the inside target and the cold outside design temperature, the more heat has to be put in to hold the temperature.
Multiplying the area allowance by the temperature difference gives an estimated heating load in kW to match against a heater or system.
A quick estimate multiplies the floor area by a heat-loss allowance per square metre set by the insulation level, then scales it for the indoor-to-outdoor temperature difference. It gives a kW figure to size a heater against — for a typical 30 m² room that’s often in the 2–4 kW range.
It’s the gap between the temperature you want inside and the cold outdoor temperature you design for. A larger difference — a cold climate or a warm target — means a higher heating load. This tool uses your indoor and outdoor figures to scale the result.
Insulation directly reduces how fast heat escapes, so a well-insulated space can need less than half the heating of a draughty one of the same size. Improving insulation often cuts running costs more than upsizing the heater.
No. It’s a rule-of-thumb estimate. A proper heat-loss calculation uses the U-values of each building element, air infiltration and ceiling height, and should be done by a competent designer for important jobs.
This calculator is a rule-of-thumb estimate for guidance only. Accurate heating load requires a full heat-loss calculation using building element U-values, infiltration and volume, carried out by a competent HVAC designer or installer.
traqR takes your sizing through to a quote, job and invoice with the equipment on the job card. Try it free for 14 days.