How much will it cost to run my European Heritage underfloor heating system?

This is a very common question and the simple answer is that running costs are determined by many different factors there are and should never be a negative factor.

It costs much less than you think!  It is a common misconception that electric underfloor heating is expensive to run.  It is not.

However, it is too easy to say “how long is a piece of string” and so the following is considered a sensible explanation.

Radiant floor heating is the most efficient form of heating possible, and the larger the floor area heated, the more efficient the heating system is.  Radiant floor heating is more efficient than radiators and other forms of convected heat, and also requires no maintenance.

The most economical systems from a running cost point of view will be those installed with floor insulation in well insulated rooms.  For example, in a well insulated new building (in-line with current building regulations) running costs would only be around £4 per square metre per year.

Factors influencing the running cost include some of the following, and these must be considered when calculating and estimating the cost.

1.  How long will the heating operate.  For example, when we estimate £4 /m² this assumes electricity at 7.5 pence per kilowatt hour, and you are heating the room for around 150 days a year for ten hours a day and supplying power for 20% of that time.

2. In a similar way a conservatory will have a running cost of approximately £8 per square metre per year, this time though based on heating the room for 200 days a year, 8 hours a day and supplying power for 35% of that time.  It is probably true that most systems in conservatories are used much less than other rooms but the heat losses in a conservatory are naturally much larger.

3. Because electrical heating systems can easily be zoned by thermostatic control, each room can be controlled independently and so you only use just enough energy to maintain your desired temperature.

4. The desired temperature could be higher in some rooms than others.

5. The thermostats are also timers and will only energise the system when programmed to operate that way.

6. Insulated floors.  The closer the insulation layer is to the underfloor heating the more effective it will be.  Insulation tile-backer boards are a good example of this, as they provide a thermal barrier, directing more than 95% of the heat upwards.  This is particularly the case on concrete floors.  Concrete floors without a thermal barrier like tile-backer boards will absorb around 30% of the heat energy downwards until stabilisation of the installed heat energy takes place.  This is not normally a problem because most floors will have insulation below the top screed as a minimum, but the time taken to stabilise will be longer than a floor with tile-backer boards placed directly under the heating.

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