When you're looking beyond just the upfront cost of installing ThermoSphere Mesh electric underfloor heating, understanding the running costs is crucial for smart budgeting. The idea of underfloor heating sounds luxurious, but it doesn't have to come with luxury level prices.
This blog explores those running costs using the ThermoSphere running cost calculator and places them in the context of current UK electricity prices. Not only this, we'll let you in on a couple of secrets for keeping your costs down.
Energy costs will vary depending on a multitude of factors:
So bear these things in mind when working out any costs. But the figures you get on this calculator are an excellent place to start and a pretty good benchmark for what you can expect (if we do say so ourselves). Our running cost calculator is based on a 10 m² area with a 150 W mesh mat.
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Looking ahead to the end of 2025, this will rise slightly to 26.35 p/kWh and 53.68 p/day respectively, per the upcoming price cap.
More information and a reference for these figures can be found below.
Electricity will always rise in price. Along with everything else in the world. But if you are smart with your usage, which isn't as hard as you might think, then underfloor heating can be not only affordable but actually often cheaper than some alternatives.
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A 150 W mesh covering 10 m² uses about 1.5 kW per hour.
At 25.73 p/kWh, that's approximately 38.6 p per hour of operation (1.5kW × 25.73p/kWh = 38.6p).
That means if you run it for 3 hours a day, you'd spend roughly £1.16 per day (3 × 38.6 p = £1.16), or around £34.80 per month assuming 30 days.
These figures are estimates based on current data (September 2025). The ThermoSphere calculator will provide a more tailored figure, but this gives a useful frame of reference based on current UK averages. It is a good benchmark for you to start budgeting. If you want to talk to someone about this or work together to get an even closer estimate, please don't hesitate to get in touch below.
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The key point is this: regardless of whether your ThermoSphere Mesh system is rated at 100 W, 150 W, or 200 W per square metre, the total amount of energy required to heat a room from, say, 15 °C to 20 °C is essentially the same, no matter how fast you do it. The thing that really impacts the running costs will be heat loss from the room, which is mainly governed by the fabric of the building, for example insulation in walls, double glazing etc.
So, what’s the real difference between output levels? It’s the speed at which that heat is delivered. A 200 W/m² system will reach the target temperature more quickly than a 100 W/m² system, which can be particularly useful in rooms that are used in short bursts—like bathrooms or ensuites. But crucially, it doesn’t mean that the 200 W system will keep drawing more energy indefinitely. Once the desired temperature is reached, the thermostat will cycle the system on and off as needed, just like any other output level.
So, while different output levels can affect how quickly a room heats up, they do not significantly affect the overall running costs—especially when the system is being used with proper insulation and smart thermostatic controls.
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Insulation boards, for example, are one of the most effective ways to improve the efficiency of an electric underfloor heating system. By reducing heat loss through the subfloor, quality insulation boards help the system retain more warmth within the room itself rather than allowing it to dissipate downwards. In practical terms, this can almost halve the amount of energy needed to maintain a comfortable floor temperature. Less heat loss means the heating system doesn't need to work as hard or for as long, to achieve the desired effect. This directly reduces the amount of electricity consumed.
Another key factor is the use of a smart, programmable thermostat. Intelligent thermostatic control plays a vital role in minimising wasted energy by allowing users to precisely schedule heating times and set temperature limits. Pairing the thermostat with a floor temperature sensor ensures that the heating is only active when it's genuinely needed, rather than running continuously. This not only improves comfort by delivering heat exactly when and where it's needed, but also avoids over-heating and excessive energy use, especially in well-insulated homes where residual warmth can last for hours.
Lastly, the overall insulation and airtightness of your home can have a significant impact on running costs. In a well-sealed, energy-efficient space, warm air stays put for longer—reducing the frequency and duration with which the heating system needs to cycle on. If your property is poorly insulated or draughty, more heat escapes, meaning your underfloor system has to work harder just to maintain a steady temperature. Improving wall, loft and window insulation will not only benefit your underfloor heating efficiency but also lower your overall energy bills year-round.
Together, these factors can help maximise the return on your underfloor heating investment by reducing how much energy is required to maintain comfort. Even small improvements, like using the correct insulation board thickness or tweaking thermostat settings, can lead to meaningful savings over time. For example, in a 10m2 bathroom, turning your thermostat down by just 1 degrees can save you up to £30 a year on your energy bill. To find out more about maximising your money saving with electric underfloor heating (EUFH) check out this blog below.
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Final thoughts
In essence, for a standard ThermoSphere Mesh system (10 m², 150 W), you're likely looking at around £1.50–£1.70 per day, depending on regional and tariff specifics. There are ways you can be clever with your heating and lower you costs, but on the whole, this is where you would be when budgeting. To find out more about other aspects, check the blogs below.
❓📊 What Does Mesh Actually Cost 📊❓ Mesh 2,3&5
Electric heating made easy
Or contact us via the website, or give one of the team a call on 01622 689440. Find out more about ThermoSphere by reading of one of our other blogs here.
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