Best Thermostat Settings to Save Energy at Home in Spain

Setting your thermostat just a few degrees differently can have a noticeable effect on how much energy your home uses. This is particularly relevant in Spain, where air conditioning can become a major source of electricity consumption during hot summers, while homes in colder areas may require significant heating during winter.

But what is the best thermostat temperature to save energy without making your home uncomfortable? There is no single temperature that works for every household. Where you live, the quality of your home’s insulation, the type of heating or cooling system and even whether the property is occupied all year can influence the ideal setting.

However, official energy-efficiency recommendations provide a useful starting point. Spain’s Institute for Energy Diversification and Saving (Instituto para la Diversificación y Ahorro de la Energía o IDAE) recommends around 20–21°C for heating when you are at home, while 26°C or above can provide adequate comfort for cooling in summer when appropriate clothing is worn.

Rather than constantly adjusting the thermostat, the most efficient strategy is usually to find a sensible temperature and adapt it according to when your home is occupied.

 

What temperature should you set your thermostat in winter?

 

For heating, IDAE recommends setting the thermostat to around 20–21°C when you are at home. Turning the thermostat considerably higher may make a room feel warmer, but it also increases the amount of energy required to maintain the larger difference between the indoor and outdoor temperatures.

In fact, IDAE estimates that increasing the temperature of a home by just 1°C can increase heating energy consumption by approximately 7%. This means that setting your heating to 24°C rather than 21°C is not a minor adjustment from an energy perspective.

It is also important to avoid a common thermostat mistake: setting the temperature extremely high because the house feels cold. If you arrive home and the temperature is 16°C, setting the thermostat to 27°C will not normally make a conventional heating system warm the property faster than choosing a sensible target temperature. Instead, you risk leaving the heating operating for longer and overheating the house.

At night, your requirements change. IDAE indicates that 15–17°C can be sufficient for sleeping comfortably, and generally recommends switching the heating off overnight and turning it back on when required in the morning. In a poorly insulated home that loses heat rapidly, maintaining a lower overnight temperature may sometimes be more appropriate.

This is where programmable thermostats become particularly useful. Instead of remembering to change the temperature every evening and morning, you can create a schedule that follows your daily routine automatically. So, your thermostat should represent the temperature you actually want the home to reach. 

 

What is the best thermostat setting in summer in Spain?

 

Cooling presents the opposite challenge. The lower you set your air conditioning, the harder the system generally has to work to maintain the difference between indoor and outdoor temperatures.

IDAE considers 26°C or above sufficient to maintain comfort in a home during summer when suitable clothing is worn. That may initially sound high to someone accustomed to setting air conditioning to 20°C or 21°C. But the objective is not to make your home cold. It is to create a comfortable indoor environment while avoiding unnecessary electricity consumption.

There is another common misconception worth addressing. Setting your air conditioning to 18°C when you arrive at a very hot property does not make the room cool down faster. IDAE specifically advises against setting the thermostat lower than normal when switching on air conditioning because it does not accelerate the cooling process and can result in excessive cooling and unnecessary energy use.

Instead, choose the temperature you actually want. Your thermostat should also work alongside other ways of controlling heat. Closing blinds or shutters during periods of intense sunlight can reduce solar heat entering the property. During cooler nights and early mornings, natural ventilation can help lower indoor temperatures before the day’s heat builds up.

Ceiling fans can also improve perceived comfort through air movement while consuming considerably less electricity than air-conditioning systems. These measures reduce the cooling load rather than simply asking your air conditioner to compensate for every source of heat.

 

Should you change the thermostat when you leave home?

 

Yes, but how much depends on how long you will be away. Maintaining exactly the same indoor temperature when nobody is home means your heating or cooling system may be consuming energy to provide comfort to an empty property.

For shorter absences during winter, IDAE recommends reducing the thermostat to around 15°C. For longer periods, the strategy will depend on the property, season, climate and equipment installed. 

This is particularly relevant for holiday homes in Spain. For example, a second home on the Mediterranean coast faces very different conditions from a property in Madrid or a house in the mountains.

If you leave your Spanish property empty for weeks or months, there is usually little reason to maintain the same comfort temperature you would use while living there. However, completely switching off climate control is not automatically the best solution in every property.

Humidity, freezing temperatures in colder areas, pets, plants, sensitive equipment and the characteristics of the building can all influence the minimum conditions you need to maintain. A smart thermostat can be especially useful for second-home owners because it allows you to check and, depending on the system, adjust the temperature remotely.

Instead of cooling or heating an empty property continuously in preparation for your eventual return, you may be able to change the setting remotely before you arrive.

 

A smart thermostat helps, but the settings still matter

 

A smart thermostat does not make heating or air conditioning inherently efficient. Its main advantage is control. Programmable and smart thermostats can automatically change settings depending on time of day, occupancy or your routine. Some systems can also be controlled remotely and provide information about energy use.

For example, a household might use a comfortable heating temperature while everyone is at home, automatically reduce it overnight and avoid maintaining the same temperature while the property is empty during working hours. 

In summer, the same principle applies to cooling. This reduces the risk of leaving air conditioning or heating operating unnecessarily simply because somebody forgot to adjust the thermostat.

However, technology cannot compensate for an inefficient setting. A sophisticated smart thermostat programmed to maintain 19°C throughout a Spanish summer can still result in high electricity consumption. The real benefit comes from combining appropriate temperatures with intelligent scheduling.

 

Your thermostat is only part of your home’s energy efficiency

 

If your heating or air conditioning seems to run almost continuously even with sensible thermostat settings, the problem may be somewhere else. Poor insulation, air leakage around windows and doors, excessive solar gain, dirty air-conditioning filters or inefficient equipment can all increase the amount of energy needed to maintain a comfortable temperature.

Thermostat location can matter too. A thermostat should measure conditions in a representative part of the home. If it is located next to a heat source, in direct sunlight or in an unusually cold area, its readings may not accurately represent the temperature experienced throughout the property.

For homes with separate rooms or zones, individual temperature control can also help avoid conditioning areas that are rarely used. This is why reducing energy consumption requires looking beyond a single thermostat number. 

The objective is to reduce the amount of heating or cooling the building needs while controlling the system efficiently. Better insulation, appropriate shading, efficient windows, properly maintained HVAC equipment and sensible thermostat settings all work together.

 

So, what are the best thermostat settings to save energy?

 

As a practical starting point for a home in Spain, you can use the following reference:

• Winter while at home: around 20–21°C
• Winter while sleeping: heating can generally be switched off; if heat needs to be maintained, around 15–17°C can be sufficient
• Short winter absence: reduce the thermostat to around 15°C
• Summer cooling: around 26°C or above with appropriate clothing

These temperatures are guidelines rather than rigid rules. Comfort varies between people, properties and regions, and households with specific health or accessibility needs may require different indoor conditions.

The most important principle is to avoid unnecessary extremes. Turning heating up several degrees in winter or setting air conditioning extremely low in summer can substantially increase energy use without providing a proportional improvement in comfort.

 

Conclusion: small thermostat changes can make a real difference

 

The best thermostat setting is not simply the lowest temperature you can tolerate in winter or the highest you can tolerate in summer. It is a balance between comfort, occupancy and energy efficiency.

For homes in Spain, keeping winter heating around 20–21°C and summer cooling around 26°C or above provides a useful starting point. From there, programmable schedules can reduce unnecessary climate control while you are sleeping or away from home.

And remember that the thermostat is only one part of the equation. If your home requires constant heating or cooling to remain comfortable, improving insulation, shading, windows or HVAC efficiency may deliver greater long-term savings than repeatedly adjusting the temperature.

At Evergreen Eléctrica, we help homeowners in Spain understand and optimise their electricity consumption. From choosing an electricity tariff that matches your household to solar self-consumption and smarter energy management, our team can help you identify practical ways to make your home more energy efficient and reduce unnecessary electricity costs.