Inside Spanish Homes: Temperatures Span 6.8°C to 25°C

Living between 6.8°C and 25°C: Spain’s thermal map

In one home, the thermometer read 11.8 degrees upon waking and 6.8 after airing out the room. In another, 25 degrees with central heating on. This is not a measurement error: these are temperatures declared in Spanish households during a cold snap, and the gap between them explains almost everything discussed afterward regarding heating, insulation, and bills. Indoor temperature now functions as a social marker as precise as the postal code.

From 8 to 25 degrees: where decent housing stands

There is a vague consensus: comfort lies between 21 and 23 degrees, with some stretching it to 26 and others lowering it to 19-20. At 16, multiple voices agree, you are already cold. The real range is much wider. 13 degrees in a bathrobe, una manola, and flannel sheets. 11.9 with aerothermal heating just started. 8 degrees as the threshold to press the power button. And at the other extreme, 22 with two split units, 24.5 in a short-sleeved shirt with -2 degrees outside, and up to 30-39 in warm climates.

The orientation of each room makes a difference: 21 degrees in a south-facing living room and about 15 in north-facing rooms within the same house. Construction, however, rarely helps. An extension built 35 years ago, without current materials or money to pay for them, stays at 11.8 degrees and 86% humidity at dawn. Spain Mark, someone summarizes with irony.

How much does it cost to heat the house for a morning?

Here is the shocking figure. A home with a condensing natural gas boiler, circuit at 47 degrees for two hours and then at 42 for three more, with a dehumidifier running full time changing rooms every hour, costs around one euro. One euro to have a child playing house in the living room. The full breakdown of that calculation—hours, circuit temperatures, power, and kilowatt price—fills an entire sheet of numbers.

More debated is the glass of water. One minute in a 1,400-watt microwave is 0.023 kWh, which at 0.15 euros per kWh costs 0.35 cents. The comparison with the cost of heating dozens of liters for a shower leaves some with raised eyebrows: some claim such a difference is impossible and the calculations are done with bad faith. The answer is that the microwave also spends energy illuminating, rotating the plate, and heating the cup itself, and the price per liter is not comparable between gas and electricity. A third calculation ignites the issue entirely: 10 cents for a two-minute infusion in the microwave, according to a published electricity tariff. Against the calculated 0.70 cents, the discrepancy ranges from 15 to 30 times, depending on how you look at it.

Thermal clothing, bathrobe, and blanket: the strategy of those who don’t turn it on

Half of Spain seems to have turned energy saving into a sporting discipline. Some don’t turn it on until eight in the evening and endure with two overlapping tracksuits. Some declare themselves cool and well-preserved. Some argue that with thermal clothing available, turning on heating earlier is nonsense, setting the start threshold at 8 degrees. Others admit the house stays at 15 because the split units, from the year of the polka, touch the casing and won’t start, and the makeshift fixes no longer work.

The counterpoint comes from those who live with air conditioning 365 days a year, who don’t drop below 23-24 as soon as the fireplace is lit, and who exceed 25 with central heating. Between these extremes lies the variable almost no one discusses: humidity. Dry cold is tolerable; humid cold, with 85% outside, seeps into the bones. 86% humidity at 11.8 degrees doesn’t feel the same as 50% at 18.

Comfort has an owner: children and couples

Here the consensus breaks. A house at 12 degrees is sustained by bathrobe, blanket, and good will until there is a minor in the living room. Those who consistently drop below 20 degrees always receive the same question: do you have kids? The expression that settles the discussion is not “saving,” it is thermal comfort, and anyone who has sat for two hours at 17 degrees with a child in front knows exactly what it means. Added to this is a domestic factor mentioned between the lines: dropping below 21 with another person in the house is a negotiation, not an individual decision.

The gap in expectations also appears. Some read the lower figures and see only superhero immune systems; others see common sense and a bill that doesn’t skyrocket. And in between, the suspicion that the thermometer doesn’t always measure what is believed to be measured.

The most expensive gas and the house that doesn’t insulate

One participant summarizes the technical background: homes built with cheap materials, contractors saving by subcontracting, gas more expensive than in much of the continent, and electricity loaded with taxes. In this framework, the debate over whether 16 degrees are cold or not starts to seem a luxury of a temperate country. Even one participant admits the real solution—improving insulation—is still waiting for a budget, although they insulated part of their house eight years ago.

With gas and electricity where they are, the gap between turning on and not turning on won’t narrow on its own. It is likely that the start threshold will rise in houses with children and remain fixed in others, while aerothermal systems and heat pumps displace oil and veteran split units. The real doubt is whether insulation will arrive before the next cold snap. Relying on the latter is what everyone has done so far.