Heating load for 100 m²: estimate and required inputs
Floor area alone does not determine the heating load of a 100 m² home. With an explicitly assumed specific design heat loss of 60 W/m², the estimate is 6 kW. The same area at 40 or 100 W/m² gives 4 or 10 kW; these are arithmetic scenarios, not recommended building ratings.
Calculate with your assumptions
What determines the load?
Record the location and outdoor design temperature, indoor set point, exposed walls, roof, floor, windows and doors, their areas and U-values, air volume and ventilation or infiltration. Two homes with the same floor area can have different exposed surfaces, insulation, leakage and outdoor conditions. Use room-by-room design losses when selecting emitters.
How to use the estimate
Enter a specific heat-loss figure supplied by a building assessment, or an assumption you want to compare. Estimated power = 100 m² × specific heat loss. To convert watts to kilowatts, divide by 1000. The form does not derive its input from the building's age or suggest a universal W/m² value.
From building inputs to a design calculation
Fabric heat loss depends on the sum of U × exposed area × temperature difference, with suitable treatment of ground contact, adjoining spaces and thermal bridges. Ventilation losses depend on air flow and temperature difference, with applicable heat recovery and infiltration treatment. Those inputs must be assessed consistently before dividing the calculated design loss by the floor area.
Power, energy and equipment
Heating load is a power in kW at stated design conditions. Annual energy in kWh also depends on weather, operating hours, controls and gains; it cannot be obtained by treating this power as an annual total. Domestic hot water and reheating requirements are separate. A heat pump's available output at design outdoor and water temperatures must be checked against its manufacturer's data.
Examples with stated assumptions
| Inputs and method | Result |
|---|---|
| 100 m² × 40 W/m² | 4.00 kW |
| 100 m² × 60 W/m² | 6.00 kW |
| 100 m² × 100 W/m² | 10.00 kW |
Result scope
This area-based comparison is an estimate using your supplied assumption. It does not replace a design heat-loss assessment or select a boiler, heat pump or electrical supply.