Radiant Floor Heating Calculator
Calculate the running cost of electric or hydronic radiant floor heating. Enter your floor area, system type and energy prices to see daily, monthly and annual cost estimates.
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Tip: Electric and hydronic systems use entirely different calculation models. The results are not directly comparable unless you are evaluating which system to install.
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System Type
Common questions
How much does electric radiant floor heating cost to run? +
A 20 m² room with 150 W/m² mats draws 3 kW installed. With a 60% duty cycle running 8 hours per day over 180 days, the annual electricity use is about 2,592 kWh. At $0.28/kWh that is around $726 per year. Smaller areas such as bathrooms cost significantly less — a 5 m² bathroom floor at the same settings would cost around $182 per year.
Is hydronic radiant floor heating cheaper to run than electric? +
For whole-house heating, hydronic systems are generally cheaper to run because they use a boiler or heat pump rather than direct resistance heating. A heat pump with COP 3.5 delivers 3.5 units of heat per unit of electricity, making it far more efficient than a 1:1 electric element. Electric systems suit smaller supplementary areas — bathrooms, kitchens, entrance halls — where low installation cost matters more than running cost per kWh.
What is a duty cycle for electric radiant floor heating? +
Duty cycle is the proportion of scheduled hours that the heating element is actually drawing power. A thermostat cycles the system on and off to maintain the set floor temperature. In practice, a well-set thermostat typically results in the system running 50-70% of the scheduled time. A duty cycle of 100% means no thermostat control — the element runs for the full scheduled hours every day.
Does water temperature affect hydronic radiant floor heating costs? +
Water temperature affects heat pump efficiency significantly. A heat pump supplying water at 35 °C typically achieves COP 4.0 or higher. At 55 °C, COP may fall to 2.5 or below. Radiant floor systems are well suited to heat pumps precisely because they can operate at low flow temperatures — typically 30-45 °C — which keeps COP high and running costs low. Gas and oil boilers are less sensitive to flow temperature in this range.
Electric vs hydronic radiant floor heating — understanding the costs
How are electric and hydronic radiant floor heating costs calculated?
The two systems use entirely different energy models and should not be compared using the same formula.
Electric radiant floor heating
Cost is driven by installed wattage, how long the system runs and how much of that time the element is actually drawing power. The formula is: installed power (kW) x duty cycle x hours per day x days per year x electricity price. Duty cycle reflects thermostat behaviour — a well-set thermostat typically results in the element running 50-70% of scheduled hours. The key variable is installed W/m², which ranges from about 100 W/m² for heating foil to 160-200 W/m² for cables and high-output mats.
Hydronic radiant floor heating
Cost depends on total heat demand, heat source efficiency and fuel price. Annual heat demand is estimated from floor area and insulation level (kWh/m2/yr). The heat source — gas boiler, oil boiler or heat pump — then delivers that heat at a given efficiency or COP. A gas boiler at 90% efficiency consuming 13,333 kWh of gas to deliver 12,000 kWh of heat at $0.07/kWh costs around $933 per year. A heat pump with COP 3.5 uses only 3,429 kWh of electricity to deliver the same heat — but at $0.28/kWh electricity that is $960 per year. The economics depend entirely on your local fuel and electricity prices.
Why water temperature matters for heat pumps
Radiant floor systems are the ideal partner for heat pumps because they deliver comfortable heating at low flow temperatures — typically 30-45 °C. At these temperatures, air source heat pumps typically achieve seasonal COP of 3.5-4.5. If the system requires higher flow temperatures, COP falls and running costs rise. When designing a hydronic radiant system with a heat pump, it is worth checking that the floor circuit can be designed to operate at the lowest flow temperature your heat pump supports.
To compare your current boiler against a heat pump for whole-home heating, use the Boiler vs Heat Pump Calculator. For electric-only underfloor heating in a single room, try the Underfloor Heating Cost Calculator.