Underfloor heating calculator for Tenerife

How much heating your room needs, which product fits your floor, and — the question nobody answers honestly — what it actually costs to run each month. The arithmetic is shown below the result, so you can check it.

How the numbers are worked out

• Heated area is smaller than the room. You don't run heating under a bath, a kitchen island or a fitted wardrobe, so usable area is 70–85% of the floor depending on the room.
• Output follows the building, not the fashion. 150 W/m² for bathrooms and older Canarian construction with little insulation; 100 W/m² where the building is well insulated and the heating is for comfort rather than as the main source.
• Product follows the floor. Heating mat under tile and porcelain; heating film under laminate and vinyl, because film is thinner and spreads heat across a floating floor.
• It is not drawing power all the time. A thermostat cycles the system on and off once the floor is warm. We assume it runs about 40% of the hours you have it on in a poorly insulated building, 30% in a well insulated one — that duty cycle is the single biggest factor in the bill, and any calculator ignoring it is overstating your cost by two to three times.
• Heating season here is roughly November to March — about five months, and mostly evenings.

Why running cost matters more than the purchase price

Electric underfloor heating is cheap to buy and the cost that worries people is the electricity. Most suppliers avoid the question. A 12 m² living room in an older Tenerife house works out at a few euros a week over a five-month season — considerably less than most people assume, and worth knowing before you decide rather than after.