Get the heat right.
Estimate room heat loss and explore radiators.
Living room
- Length
- 4 m
- Width
- 5 m
- Height
- 2.4 m
- External walls
- 2
- Glazing
- Custom · U 2.8
- Wall construction
- Custom · U 1
Editable starting estimates; illustration is decorative, not a measured floorplan.
Calculation assumptions
Starting values are editable assumptions, not a construction survey. Use measured U-values, local outdoor design temperature and ventilation rate. A heated adjoining space at the indoor temperature contributes zero floor or ceiling loss.
Fabric loss: Σ(U × A × ΔT). Ventilation: 0.33 × air changes/hour × room volume × ΔT. Net external wall area is height × (length × length walls + width × width walls), less windows and external doors. Floor and ceiling use their own boundary temperatures. No safety factor, thermal bridging or certification is implied. 1 W = 3.412142 BTU/h.
Windows and doors must fit within the external wall area. Indoor temperature must exceed outdoor temperature; floor and ceiling boundaries cannot be warmer than indoors. All inputs must stay within the indicated limits.
Open University: building heat lossesEnergy Saving Trust: heat-loss guidanceExplore radiators for this room
Check manufacturer-rated output at your system temperatures. Output matching is not available.
Planning several rooms?
Keep room calculations together in a project on this device.