What temperature should the air conditioning be set to in a rental or hotel?

A comfortable room sits at about 22 to 26°C. Guests routinely set it to 16 to 18°C, and because each degree lower adds 7 to 10% to the cooling load, the gap between the two is pure waste, worth €190–450 per AC unit per season. The fix is not a colder rule or a warmer one. It is holding the room inside the comfort band.

The short answer

Set the air conditioning inside the recognised comfort band of roughly 22 to 26°C. Most guests will not notice the difference between 22°C and the 18°C they tend to reach for, but the bill will. The two settings that cost you money are the extreme cold a guest dials in on arrival, and the hours the unit then runs in an empty room. Both sit outside the comfort band, and both are avoidable without making a single guest uncomfortable.

What the standards actually say

There is no need to guess what counts as comfortable. Two recognised standards define it, and they agree closely.

• ASHRAE 55, the international thermal comfort standard, puts the summer comfort zone at roughly 22.5 to 26°C for normal clothing and activity.
• EN 16798-1, the EU standard, places the summer comfort range at about 23 to 26°C, with its highest comfort category, the one suited to hotels, around 23.5 to 25.5°C.

Put plainly, a room at 22 to 24°C is comfortable for almost everyone. A room at 16 to 18°C is not more comfortable, it is just colder, and the extra cold is paid for in full.

Two different bands, often confused

It is easy to mix up two things that sound similar but are not. There is a comfort band, about 22 to 26°C, which is what the standards above describe. And there is an energy-austerity band, about 26 to 27°C, which is the warmest setting authorities recommend to cut consumption. In August 2022 Spain went further and made it law for a time: under Royal Decree-Law 14/2022, public and commercial buildings including hotels could not cool below 27°C.

Austerity limits are useful as a reference point. They tell you that even the most aggressive official guidance says do not cool below 27°C, while guests are setting 16°C, eleven degrees lower. But 27°C is not a comfort target. To a paying guest it reads as the AC barely working. The useful answer is neither the guest's 16°C nor the regulator's 27°C. It is the comfort band in between.

The detail most operators miss: 18°C is a heating number

When an operator does try to set a floor, 18°C is the figure that tends to get chosen. It feels like a sensible, slightly-warmer minimum. But 18°C is close to the World Health Organization's recommended minimum for a heated home in winter. It is a cold-weather health floor, the temperature below which a room is considered too cold for occupants in winter. It was never meant as a summer cooling target.

So a cage or a lock that caps the remote at 18°C is still holding the room four to eight degrees below the comfort band all day. It looks like restraint. It is still paying for cold nobody needs.

Why guests go below comfort in the first place

Two reasons, and neither is malice. First, a hot guest walking into a hot room presses the temperature all the way down because lower feels faster, even though the room cools at the same rate whether the target is 16°C or 22°C. Second, the guest is not paying the electricity bill. With no marginal cost to them, there is no reason to be careful, so the unit gets set low and left running while they head out for the day.

This is not a problem you fix with a sign asking guests to be considerate. It is a problem you fix by quietly removing the settings that are outside the comfort band, while leaving the guest in full control inside it.

What the gap is worth

Every degree below the comfort band adds roughly 7 to 10% to the cooling load, and a guest who drops a room from 24°C to 16°C can lift energy use by up to 70%. Add the hours the unit spends cooling an empty room, and the recoverable waste comes to €190–450 per AC unit per season. For a single property the maths scales straight off the unit count: a 9-room hotel recovers roughly €2,800 a year, a 50-room hotel with 50 AC units recovers €9,500–22,500 a season.

The operator's way through

Narveo was built by a vacation rental operator in Ibiza, after years of watching guests leave the AC running at 16°C all day, and it is still used in the founder's own properties. Instead of arguing about a single number, it enforces the comfort band. A guest can still pick up the remote and adjust the temperature. What changes is that a setting below the band simply resolves to the nearest comfortable one, and the unit auto-shuts off after a set time so an empty room stops cooling itself. The extreme cold is gone, the empty-room runtime is gone, and the guest never feels controlled.

It sets up in under 2 minutes, costs €69 per unit, and works with 6,000+ AC codes. No app. No WiFi. No installation. The guest keeps a comfortable room. You keep the saving.

FAQ

When Narveo is not the right solution

Narveo is designed for warm-climate rentals and hotels where split AC units run continuously through a four-to-six month peak season. Properties in cool climates, where guests rarely use the AC during the day, will see proportionally less return. Narveo is not compatible with ducted or centralised BMS systems, and it is not suited to owner-occupied properties where usage is already self-managed.