Condizionatore in autunno: 7 consigli per scaldare e risparmiare

A warm home and a low energy bill? Here's how to use air conditioning in autumn to save money and protect your health.

October arrives, the days get shorter, and the house gets colder, especially after the sun goes down. The central heating hasn't started up yet, or you can't turn on the radiators because the local government ordinance hasn't yet given the go-ahead. Besides, let's face it, turning on the boiler for just two colder hours seems like a waste, especially after the latest gas price hikes.

Why not consider the air conditioner? Indeed, a split system unit can offer you all the comfort of cool air in summer, but can also provide heating. And during spring and autumn, it's almost always the cheapest way to do it.

Below are 7 practical, tried-and-tested tips for getting through autumn with your home at the right temperature, with healthy air and energy consumption under control.

Your air conditioner is (almost) a heat pump

Calling it an "air conditioner" nowadays is an understatement. A modern split-system air conditioner is, in effect, a reversible air-to-air heat pump: in the summer, it extracts heat from the rooms and discharges it outside; in the winter, it can do the opposite, drawing thermal energy from the outside air and bringing it into the home.

There's a substantial difference compared to a boiler. A boiler produces heat by burning gas: from one unit of input energy, you get, at best, just under one unit of heat. Heat pumps, on the other hand, do not produce heat; they move it from outside to inside or vice versa. For every unit of electricity, they transfer three, four or even more units of heat into the home. That's why, in autumn, when outdoor temperatures are mild, heating with a split-system air conditioner can be more economical than combustion-based alternatives.

Clivet split systems have been designed precisely for this dual use: they are responsive, quiet units that can be controlled via an app, designed to operate all year round and not just during the hot summer months.

Good to know: If your system is already a few years old, check the SCOP entry in the manual or on the energy label. This is the seasonal heating efficiency index: the higher it is, the less energy you consume.

Why autumn is the season when we waste the most

Spring and autumn are unpredictable. The outdoor temperature may fluctuate quite a bit: less than 10 degrees between 7 and 10 a.m., but then maybe reaching nearly 20 degrees by midday and throughout the early afternoon. So, as soon as we get out of bed, our instinctive reaction is to turn on everything full blast, but this sort of behaviour costs the most and heats the least efficiently.

Here are three common errors to avoid.

Switching the heating on for a short time and at maximum power

The start-up is the least efficient part of the cycle. Doing this several times a day negates the benefit of inverter technology because, in the first few minutes after turning it on:

the coolant and oil have retreated during the pause in operation; the circuit is not ready to go
the heat exchangers and metal parts have to get to the right temperature before releasing any useful heat

To ensure your heat pump works well in autumn and to avoid wasting energy, you should never turn it on at maximum power for just a short time. On the contrary, it should be started up gradually. If you turn it up to the maximum when it's cold and damp outside, frost will immediately form on the outdoor unit. To defrost this ice, the heat pump has to "reverse" its operation: it stops heating and removes heat from inside the house to defrost itself outside. Turning it up to maximum for short periods creates a vicious circle: the unit will constantly defrost, consume more energy, and the house will be much harder to heat.

Confusing chilliness with humidity

When it's 20°C with 75% humidity, it's quite normal to feel cold. Turning on the radiator might seem obvious, but it's the least logical move: you don't need to combat the low temperature, you need to get rid of the damp. Simply heating the air doesn't actually remove moisture from the environment: it changes the relative humidity, not the absolute humidity (the "dew point"- the temperature at which the air reaches 100% humidity and begins to dampen surfaces - remains the same even if the temperature has risen by a few degrees).

The correct approach is rather different: remove the moisture, don't add extra heat. Bring the relative humidity back to 45-60% using the dehumidifier mode, and you'll find that 20°C is quite sufficient. The walls will dry out and provide proper insulation once again, and the perceived temperature will rise without you adjusting the set point.

There's also a reason that doesn't relate to your bill. At relative humidity levels above 60%, environmental conditions can arise that are conducive to the proliferation of dust mites, as well as to the formation of condensation on cold surfaces and the growth of mould.

Below 40%, on the other hand, the air becomes too dry and may irritate the airways. The range between 45% and 60% is where you feel comfortable and your home feels comfortable.

Heating unnecessary cubic metres

A split-system unit doesn't heat an entire house - it heats the air in the room where it's located. But air doesn't stand still: this means that every door that's left open - or even just slightly ajar - to a room you're not using is an invitation to let heat spread where it's not needed. So, the bathroom door, the utility room door, the stairway door - if you have a multi-storey house - should be kept closed when the air conditioners are running.

Wasting rather than using heat from the sun

And finally, a tip that doesn’t involve using air conditioners: take advantage of what comes free.

In the middle of the day, when the sun is high in the sky, raise the blinds in south-facing rooms; the sun, shining through an average window, provides several hundred watts of energy, enough to raise the temperature in the room. At sunset, on the other hand, close everything: shutters and heavy curtains significantly reduce heat loss through the windows at night, which remain the weakest point in the outer casing of your home.

7 tips for using the air conditioner to heat your home in autumn

1. Set the correct temperature and avoid sudden temperature changes

In autumn, the ideal set point is between 20 and 23°C. Below 20°C, comfort levels drop, especially if it's humid. Above 23°C, energy consumption is higher without any real perceived benefit.

Equally important is the difference between indoor and outdoor temperatures: too great a temperature difference - especially when you go in and out of the house several times a day - puts stress on the respiratory system and increases the risk of getting the colds and sore throats that are typical of this time of year. A home with a steady temperature of 21 - 22°C is healthier than one where the temperature fluctuates up to around 25°C.

2. Use the dehumidifier mode on rainy days

This is the tip that delivers the most immediate results. On rainy or overcast days, when the air is saturated with moisture, the sensation of cold is due more to the humidity than to the temperature: humid air draws heat away from the body much more quickly than dry air.

Turn on dry mode (dehumidification); the unit will condense the moisture in the air and drain it away outside. Bringing the relative humidity back to the 45% - 60% range completely changes the perceived temperature of the room, with significantly lower electricity consumption compared to operating at full heating capacity.

3. Close the doors of rooms not in use

Every door that opens into an unused room adds space that needs to be heated, and creates drafts that disperse the heat that has just been introduced.

If you have a MULTISplit system, this is even more important: you can just keep units on in the rooms that are actually occupied, and turn off the others. Heat where it's needed, and when it's needed, and the outdoor unit will modulate the power accordingly.

4. Point the deflectors downwards

Warm air is less dense and rises by itself. If you leave the vents in the horizontal position, which is most appropriate in summer, the heat will rise to the ceiling and you'll continue to feel cold at floor level.

In heating mode, point the vents downward so that the warm air is directed toward the floor and then rises, distributing itself evenly throughout the entire height of the room. The temperature that people actually feel is reached sooner, and the thermostat stops the unit from running unnecessarily.

5. Make the most of thermal inertia

The walls, floors and furnishings store heat and release it slowly back into the room. It is a free resource which many people fail to exploit.

Switch off the air conditioner 15–20 minutes before leaving the house or going to bed. The room will stay at the right temperature for as long as you need, without burning off so much as a single extra watt of energy. In a well-insulated flat, the temperature will drop by just a few tenths of a degree.

The same principle applies in reverse: in a house with good inertia, a stable, constant temperature is preferable to temperature spikes and repeated turning off of the air conditioner.

6. Check and clean the filters before switching on the air conditioner for the first time

After a season of cooling and a few weeks of inactivity, dust, pollen and residual moisture can build up in the filters. Turning the air conditioner back on without cleaning the filters causes all the deposits to be released back into your home and, with the windows closed, the air quality indoors deteriorates quickly.

There is also a direct effect on energy consumption: a blocked filter reduces the flow of air, forcing the fan to work harder and reducing the efficiency of the heat exchanger.

Cleaning takes about ten minutes and should be repeated every 3–4 weeks of intensive use. In addition, have a qualified technician carry out an annual inspection.

7. Set a timer rather than turning the heating right up when you feel cold

Switching on the air conditioner in a reactive manner (‘I’m cold, so I’ll turn it right up’) does not allow the inverter unit to be put to its most effective use; it works best when operating at reduced load for long periods.

Use the weekly timer or the app: set it to start 30 minutes before you wake up and before you get home, with a constant set point. The house is already at a comfortable temperature when you come home, and the unit runs smoothly and not at full power.

If you have several indoor units, the app lets you manage them zone by zone and check energy consumption in real time, allowing you to find out where you’re wasting energy. Another thing you can do is to integrate climate control into the smart living system, coordinating air conditioning, hot water and — where applicable — solar power generation.

How much energy does a split-system air conditioner use in heating mode?

The key figure to look at is the SCOP (Seasonal Coefficient of Performance), which is the ratio of thermal energy output to electrical energy input over an entire heating season. A SCOP of 4.60 means that for every kWh of electricity drawn from the grid, the appliance returns 4.6 kWh of heat to the home.

In practical terms: during spring and summer, when the outdoor air is mild and the heat pump is operating at its most efficient, heating one or two rooms with a split-system air conditioner costs less than running the central heating system for the whole house. This is why more and more families are using their air conditioner as their main heating system from October to November and from March to April, and the boiler or hydronic heat pump only in the depths of winter.

Clivet split systems – such as the CRISTALLO 2 – are rated up to A+++ in cooling mode and A++ in heating mode, with SCOP values that make them fully suitable for use as heat generators in spring and autumn.

The Clivet Split range for an autumn without sky-high energy bills

They are not just ‘air conditioners’.

Clivet split-system air conditioners are fast, responsive and efficient, even when used to heat your home or office. They can be installed in a quick, non-invasive manner, run silently even at full capacity, and can be controlled via an app.

CRISTALLO 2: Wall-mounted MONOSplit with ALTO Design panel, for those seeking performance and style.
STELVIO: MONOSplit with adaptive comfort: the airflow adapts to people’s movements.
CERVINO and EZCOOL: essential solutions for individual rooms.
MULTISplit systems: multiple indoor units connected to a single outdoor unit, for zone-based control of the whole house.

Discover the full Split range

Frequently asked questions about air conditioning and heating

Can an air conditioner be used instead of a heating system in autumn?

Yes, in the milder seasons it usually can. When outdoor temperatures are roughly between 8 and 18 °C, the air-to-air heat pump operates at its best and can heat one or more rooms at a lower cost than running the central heating system. In the depths of winter, however, and in poorly insulated buildings, it can be used to supplement rather than completely replace the central heating system.

What temperature should you set the air conditioner to in autumn?

Between 20 and 23 °C. This is the range that ensures comfort without consuming too much energy and minimises the temperature difference compared with the outside, thereby reducing the risk of respiratory problems.

Does dehumidifier mode generate heat?

No, it does not generate heat: it simply reduces humidity in the air. As humid air draws heat away from the body more quickly, reducing the relative humidity to between 45 and 60 per cent, it eliminates the sensation of cold, whilst consuming less electricity than heating mode.

Is it a good idea to switch the air conditioner off and on again several times a day?

No. Inverter technology is at its most efficient when it operates at reduced power for prolonged periods. It is best to set fixed time slots and make the most of thermal inertia by switching the heating off 15–20 minutes before you leave.

Why do I need to point the vents downwards when using heating mode?

Because hot air tends to rise. By directing the air flow towards the floor, the heat does not all gather up by the ceiling and a more uniform temperature is achieved throughout the entire room.

Would you like to find out which split system is right for your home?

Find your nearest Clivet dealer

Air conditioner for heating in spring and autumn: 7 tips for autumn