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Since 1998
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Calculate heat loss to determine whether underfloor heating can comfortably heat your room.
The Underfloor Heating Heat Loss Calculator helps you estimate how much heat a room or building loses so you can design an underfloor heating system that delivers consistent comfort without wasting energy. Accurate heat loss calculations are essential to ensure your system is powerful enough to maintain desired temperatures, even during the coldest conditions.
This tool provides clear estimates that support better system design, lower running costs, and improved thermal comfort.
Heat loss refers to the amount of heat energy that escapes from a room through:
Walls
Floors
Ceilings and roofs
Windows and doors
Ventilation and air leakage
Your underfloor heating system must replace this lost heat to maintain a stable indoor temperature.
Incorrect heat loss calculations can lead to system problems.
Rooms that never reach target temperature
Excessive boiler or heat pump run times
Higher energy bills
Reduced comfort
Oversized systems
Unnecessary installation costs
Reduced system efficiency
The calculator helps strike the right balance.
The calculator estimates heat loss using building and room-specific data.
Room dimensions
Floor area
Insulation levels
Wall, floor, and ceiling construction
Window and door sizes
Indoor and outdoor temperatures
The output is a heat loss value (W or W/m²) needed to size your system correctly.
Well-insulated rooms: 30–50 W/m²
Average insulation: 50–70 W/m²
Poor insulation or large glazing: 70–100+ W/m²
The calculator tailors results to your property.
This tool is ideal for:
Homeowners planning underfloor heating
Installers and heating engineers
Architects and designers
Landlords and developers
Renovation and new-build projects
Anyone involved in heating design can benefit.
Insulation plays a critical role in underfloor heating performance.
Faster warm-up times
Lower flow temperatures
Reduced running costs
Improved comfort
The calculator highlights how insulation impacts heat loss.
Heat loss calculations apply to both systems:
Electric underfloor heating requires accurate wattage selection
Water-based systems depend on pipe spacing and flow temperatures
The calculator supports both system types.
Improve wall and floor insulation
Upgrade windows and doors
Seal drafts and air leaks
Use insulation boards beneath heating elements
Reducing heat loss can significantly lower system size and cost.
It ensures your underfloor heating system can meet the room’s heating demand efficiently.
In most modern homes, yes—if heat loss is calculated correctly.
Yes. Renovations, insulation upgrades, or window replacements affect heat loss.
It provides reliable estimates but does not replace a full professional heat loss survey.
Results are typically shown in watts (W) or watts per square metre (W/m²).
Yes. It’s completely free to use.
The Underfloor Heating Heat Loss Calculator provides estimates for guidance only. Final system design should be verified by a qualified heating professional.
An efficient underfloor heating system starts with accurate heat loss calculations. Use the Underfloor Heating Heat Loss Calculator to design a system that delivers comfort, efficiency, and long-term savings.