Building heat
Heating load calculator
Estimate the heating power required for a room or building using floor area, a heat-loss factor, and a design temperature margin.
Outputs
- Heating load in kW
- Adjusted load with margin
- Load per m2
What heating load does a 100 m2 house need at 50 W/m2?
Example build-up
Area: 100 m2. Heat-loss factor: 50 W/m2. Margin: 10 percent.
Base load is 5.0 kW and the adjusted load is 5.5 kW.
Formula
Load = area × heat loss factor
Adjusted load = load × (1 + margin / 100)
Enter the room or building details
Measurement note
This is a simplified sizing estimate. Envelope quality, ventilation, climate, and internal gains can change the real load.
What the inputs mean
Floor area
Use the space you actually want to heat, in square meters.
Heat loss factor
Lower values fit better-insulated spaces; higher values suit older or leakier buildings.
Margin
Add a small margin for cold snaps, system losses, or conservative sizing.