Energy: ENEA tips to save on air conditioning

11 July 2024 Last Updated: 11 July 2024

ENEA suggests 14 simple actions you can take this summer to save on air conditioning, increasingly widespread in Italian homes. According to an ISTAT survey^[1], 48.8% of families have air conditioning, rising to 51.2% in the South (49.1% in the North and 44.2% in the Center). At a regional level, the highest diffusion rate is in Veneto (70%), with Valle d'Aosta lagging behind with 4.7%.

The average run time on a typical summer day is six hours and 17 minutes, approximately three hours in the afternoon, just over two hours at night and an hour in the morning. Households in the smaller non-mountain municipalities (up to 50 thousand inhabitants) turn on air conditioning most frequently (31% use it every day or almost). Average daily use increases with the number of persons in a household.

Mostly the system are heat pump mono-splits (56% of the total) which can be used both to cool and heat the rooms. 24% are older versions of air conditioners, which exclusively cool, while 20% are centralized or autonomous systems which serve the entire home.

“Not all cooling devices are the same: high-efficiency heat pumps make excellent energy-saving options compared to older generation air conditioners, lowering utility bills and generating fewer carbon emissions”, explained Nicolandrea Calabrese, head of the ENEA Laboratory of Energy Efficiency in Buildings and Urban Development. “We must also consider the advantage of their dual functionality for heating and cooling. If combined with photovoltaic systems for the production of electricity, they represent a valid technology towards the decarbonization of buildings required by the new EU EPBD Directive, and the achievement of the objectives of the European Green Deal^[2]", said Calabrese.

14 tips for an efficient use of air conditioners

ENEA recommends adopting these measures when using heat pumps for summer air conditioning, to save energy and maximize environmental benefits.

Regular maintenance

Like any other household appliance, the air conditioner also requires routinely cleaning and maintenance. In addition, it is important to check the gas circuit for leaks.

Lack of proper maintenance – he said – puts great stress on air conditioning systems, causing a 30% increased power consumption compared to factory parameters.

Please note that the legislation provides for the obligation of the system booklet and routinely checks for systems with a power greater than 10 kW for winter ones and 12 kW for summer ones.

Dirty air filters and fans harbour molds and bacteria harmful to health, including the legionella bacterium which can be deadly.

Pay attention to the energy class

Choosing the right air conditioner is a key requirement for reducing consumption and avoiding nasty surprises on your bill. Regardless of the technology, models in an energy class higher than A are always preferable, since, in addition to a reduction in CO2 emissions into the atmosphere, they consume much less. The annual energy consumption indicated on the energy label is related to 1,400 operating hours in heating mode and 350 in cooling mode, plus the energy consumption in other modes like standby. For example, a class A+++ model will consume up to 40% less electricity than a class B model.

Choose inverter technology

In an air conditioner with an inverter control system, the rotational speed of the compressor is constant and this allows for optimal performance in any conditions,. These models, designed to keep the air conditioning on for many hours in a row, cost more than those equipped with on-off technology but energy consumption and noise are lower and they offer a greater comfort.

Watch out for incentives

For purchases made by 31 December 2024, the "air conditioning bonus" allows you to benefit from a tax deduction of 50% or 65%, depending on the intervention and type of system:

Tax deduction	Intervention
50%	Purchase of air conditioners as part of building renovations or extraordinary maintenance
65%	Purchase of high efficiency heat pump air conditioners to replace a lower class one

Placement of the Unit

Place the air conditioner in the upper part of the wall: cold air tends to sink and will mix more easily with hot air which instead tends to rise. Avoid installing the unit behind a piece of furniture: the barrier stops fresh air from circulating.

Close the shutters during the hottest hours

It is common practice to leave the shutters open even when you are not at home, allowing the heat to enter through the window frames. Turning on the air conditioner at your return, requires a great amount of energy to cool the rooms. Closing the shutters, or shielding the windows during the central hours of summer days can reduce the solar heat gains and consequently the energy required by the air conditioners.

Do not cool your space too much and control humidity

The legislation provides that during the summer season indoor temperatures must not drop below 24-26 degrees Celsius but, more often than not, two or three degrees less than the outdoor temperature are already sufficient. Often, to avoid the feeling of oppressive heat, activating the dehumidification mode may suffice, as humidity makes the temperature feel warmer.

You need an AC unit for every room

Installing a more "powerful" air conditioner in the corridor hoping that it will cool the entire house is useless: the only result will be to catch a cold every time you cross the corridor going from one room to another, as it will be the the only room to be cooled.

Don't leave doors and windows open

The air conditioner transfers heat and humidity outside. If “new” hot air enters the room the system will work extra hard to maintain a specific temperature and humidity level, consuming extra energy. Instead, open the windows during the cooler hours of the night if the air conditioning is not running.

Insulate the refrigerant circuit pipes outside your house

To avoid dispersions, the refrigerant pipes present outside the house need to be insulated. Cover the external part of the air conditioner from the sun and bad weather.

Use the timer and the 'night' mode

They allow you to reduce the start time interval to a minimum and increase comfort. Wireless remote allows you to turn the air conditioner on and off and keep it running only when needed. The "night" or "sleep" mode adjusts room temperature to changes in body temperature.

Use programmable thermostats

Set your thermostat to a comfortable temperature and set cooling programs to optimize energy consumption when you are away or at night. These functions allow you to reduce the run time and increase comfort. Furthermore, they allow you to turn the air conditioner on and off remotely and keep it running only for the period of time in which you really need it. The "night" or "sleep" function regulates the room temperature during the night so as to adjust to changes in body temperature.

Reduce heat flow from appliances and electronics

During the hottest hours, limit the use of appliances and electronics that contribute to increasing the internal temperature of the house.

Consider the combination of an heat pump and a photovoltaic system

The maximum advantage can be obtained by combining a heat pump with a photovoltaic system capable of supplying the electricity necessary for the operation of the system. It is essential to synchronize the air conditioner with the productivity of the system, which is maximum during the central hours of the day.

Conduct a home energy diagnosis

Let a technician conduct an energy diagnosis of the building. It’s the first step to assess the thermal insulation of walls and windows and the efficiency of the air conditioning system. The diagnosis will indicate the interventions to be carried out evaluating their cost-benefit ratio. In addition to reducing the costs for summer air conditioning of rooms by up to 40%, the interventions are even more affordable applying the tax deductions for the energy renovation of buildings.

Know your system

To optimize operation and avoid energy waste, it is essential to know how heat pumps, which are efficient and environment-friendly, work. Heat pumps take in heat from a cool source (ambient air, water, ground) and transfer it to a higher temperature location with a generally limited input of energy supplied in the form of electricity. In reversible heat pumps that flow is reversible, allowing the system to operate in cooling mode, transferring heat from inside the building to the outside. The operation is similar to that of a refrigerator which does not "create" cold, but transfers heat from inside to outside.