What is aerothermal energy and how does it work?
Aerothermal heating is an air conditioning and domestic hot water (DHW) technology that extracts thermal energy from the outside air and transfers it to the inside of a home or building. It works by means of an aerothermal heat pump, which operates efficiently in both winter and summer.
How does aerothermal energy work?
The aerothermal system is based on a thermodynamic cycle that uses a refrigerant to capture heat from the outside air, compress it and increase its temperature, and then transfer it to the inside. This process generates heating in winter, cooling in summer and hot water all year round.
Main components of an aerothermal system
- Outdoor unit: Captures thermal energy from the air and transfers it to the system.
- Indoor unit (heat pump): Regulates temperature and distributes heat/cooling.
- Domestic hot water (DHW) tank: Stores the hot water generated.
- Distribution systems: It can be underfloor heating, low temperature radiators or fan coils.
Seasonal operating cycle
In winter: It extracts heat from the outside air, compresses it and injects it into the house for heating.
In summer: It reverses the cycle and extracts heat from the inside, expelling it to the outside, functioning as air conditioning.
All year round: It produces domestic hot water with high energy efficiency.
Advantages and disadvantages of aerothermal energy
Aerothermal energy is consolidating as one of the most efficient and sustainable options for air conditioning and hot water. However, like any system, it has its pros and cons.
Advantages of aerothermal energy
- High energy efficiency: It has an efficiency (COP) of 3 to 5, i.e., for every 1 kWh of electricity consumed, it generates between 3 and 5 kWh of heat.
- Energy bill savings: Can reduce consumption by up to 70% compared to traditional gas or diesel systems.
- Renewable energy: Aerothermal energy uses air as an energy source, being more sustainable and reducing the carbon footprint.
- Compatible with solar panels: Can be combined with photovoltaic energy for even more efficient consumption.
- 3-in-1 system: Provides heating, cooling and DHW in a single system.
- Less maintenance than a boiler: It does not require mandatory periodic revisions like gas.
- No combustion or fumes: It does not generate residues, which makes it safer and cleaner.
Disadvantages of aerothermal energy
- High initial investment: The installation is more expensive than a conventional boiler, although it is amortized in about 5-7 years.
- Space requirement: Space is needed for the outdoor unit and DHW tank, which can be a problem in small apartments.
- Variable performance depending on outdoor temperature: In very cold climates, efficiency may be slightly reduced.
- Dependence on electricity: Although consumption is low, it still requires electricity.
Aerothermal vs. other air conditioning systems
Comparing aerothermal energy with other systems is key to evaluate its profitability and convenience.
| System | Energy efficiency | Initial cost | Savings in consumption | Renewable energy | Maintenance |
| Aerothermal | ⭐⭐⭐⭐⭐ High (COP 3-5) | High | Medium-High (up to 70%) | ✅ Yes | Under |
| Gas boiler | ⭐⭐⭐ Average (COP 0.9-1) | Under | Medium | ❌ No | Medium-High |
| Oil-fired boiler | ⭐⭐ Low (COP 0.8-1) | Medium | Under | ❌ No | High |
| Air conditioning | ⭐⭐⭐ Average (COP 2-3) | Medium | Medium | ❌ No | Under |
| Geothermal | ⭐⭐⭐⭐⭐ Very high (COP 4-6) | Very high | High | ✅ Yes | Under |
Aerothermics is one of the most efficient and sustainable solutions in the long term, especially in single-family homes or buildings with good energy efficiency.
Uses and applications of aerothermal energy
Aerothermal energy is not only used for heating, but is a multifunctional system capable of providing heating in winter, cooling in summer and domestic hot water (DHW) throughout the year. Below, we explore its different applications and its adaptability to different types of homes.
Aerothermics for heating, cooling and domestic hot water (DHW)
Aerothermal heating
Aerothermal heating is a very efficient system for heating, working optimally even in outdoor temperatures as low as -15°C. Its performance varies according to the type of distribution system used in the house:
- 🔹 Underfloor heating: The most efficient option, since it works at low temperatures (30-45°C) and provides homogeneous heat.
- 🔹 Low temperature radiators: Works well with aerothermics, although its performance is lower than that of underfloor heating.
- 🔹 Fan coils (fan coils): They allow fast and efficient air conditioning, working both for heating and cooling.
- 🔹 Traditional radiators: Not the best option, as they require higher temperatures (60-80°C) and reduce system efficiency.
Heating consumption and savings
- A 100m² house with underfloor heating can save between 50% and 70% compared to natural gas or oil.
- The consumption of aerothermal heating in an average apartment can be between 400 and 800 kWh/month in winter, depending on the insulation and the efficiency of the equipment.
Cooling with aerothermal energy
Aerothermics can also be used in cooling mode, functioning as an air conditioner by reversing the thermodynamic cycle.
Cooling options with aerothermal energy
- 🔹 Cooling floor: It cools the house uniformly, although its cooling speed is slower than an air conditioner.
- 🔹 Fan coils: They act as a conventional air conditioner, allowing fast and efficient cooling.
- 🔹 Air ducts: In some installations, aerothermal can distribute cool air through a duct system.
Advantages of aerothermal cooling
- It does not need an additional outdoor unit like traditional air conditioners.
- Lower energy consumption than an inverter air conditioner.
- Reduction of air dryness, offering a more comfortable environment.
Disadvantages of aerothermal energy in refrigeration
- The cooling floor has a softer effect and takes longer to cool compared to traditional air conditioners.
Domestic hot water (DHW) production
Aerothermal energy is one of the most efficient options for domestic hot water production.
Advantages of DHW with aerothermal energy
- Very high energy efficiency (COP up to 4).
- It can heat water up to 55-60°C without additional electrical resistance.
- It can be combined with photovoltaic solar panels to make consumption even more efficient.
- It requires less maintenance than an electric boiler or a gas boiler.
Aspects to take into account
- A DHW storage tank of at least 100-300 liters is required depending on the size of the house.
- In very cold climates, occasional electrical support may be required to ensure continuous hot water.
Housing requirements for aerothermal installation
Is it possible to install aerothermal energy in an apartment?
Yes, aerothermal can be installed in apartments, although there are some key considerations:
Factors in favor:
- An outdoor unit can be installed on balconies, terraces or communal patios.
- It can easily replace gas boilers in apartments with low temperature radiator heating.
- Ideal in buildings with radiant floor heating or fan coils.
Challenges and limitations:
- Space is required for the outdoor unit and the DHW tank.
- On older floors, traditional radiators may not be compatible without adjustments.
- In residential communities, there may be regulatory limitations for the installation of the outdoor unit on facades or rooftops.
Solution for small apartments:
There are “monobloc” or compact units without outdoor unit that can be installed indoors, although their performance is lower.
Aerothermics in single-family homes vs. condominiums
| Feature | Single-family homes | Apartments in neighborhood communities |
| Space for outdoor unit | Easy installation in garden or terrace | There may be restrictions on the facade or rooftop |
| Type of distribution | Ideal for radiant floor heating or fan coils | May require retrofitting if traditional radiators are present |
| System independence | 100% individualized | Shared installation in buildings may be necessary |
| Cost of installation | Medium-high, depending on the size of the dwelling | Less than in a house if central heating is already in place |
| Energy savings | Very high in well-insulated houses | Medium-high depending on the building |
- In single-family homes, aerothermal energy is highly efficient, especially when combined with underfloor heating and solar panels.
- In apartments and communities, aerothermal energy is feasible, but the available spaces and building regulations must be evaluated.
Aerothermal energy is a versatile technology that can provide efficient heating, cooling and domestic hot water (DHW). It is an ideal option for both houses and apartments, although in the latter there are certain limitations to consider.
Costs and profitability of aerothermal energy
One of the key factors when considering the installation of aerothermal energy is its initial cost, energy consumption and long-term savings. In this section we analyze the installation prices, the factors that influence the cost and the profitability of the system compared to other options.
How much does an aerothermal system cost?
The price of an aerothermal installation varies according to the type of house, the power required and the thermal distribution system.
Cost of installation according to the type of house
| Type of housing | Approximate price (including installation) |
| Apartment (80-100 m², fan coils or radiators) | 8.000 – 12.000 € |
| Apartment (100-150 m², underfloor heating) | 12.000 – 16.000 € |
| Single-family house (100-150 m², fan coils/radiators) | 10.000 – 15.000 € |
| Detached house (100-150 m², underfloor heating) | 14.000 – 20.000 € |
| Large house (200+ m², high efficiency) | 18.000 – 25.000 € |
Factors influencing price:
- Equipment power: It is measured in kW and depends on the size of the dwelling.
- Type of emitters: Underfloor heating is more expensive than radiators or fan coils.
- Difficulty of installation: New homes have lower adaptation costs.
- Location: Higher power equipment may be required in cold areas.
- Brands and models: There are price differences depending on the manufacturer.
Price of aerothermics in apartments and houses according to square meters
Depending on the size of the property, the investment may vary:
| Living area | Price of aerothermal installation |
| 70-80 m² apartment | 7.000 – 11.000 € |
| 100 m² apartment | 8.000 – 12.000 € |
| 120 m² house | 10.000 – 14.000 € |
| 150 m² house | 12.000 – 18.000 € |
| 200 m² house | 16.000 – 22.000 € |
Real example:
A 100 m² house with underfloor heating and aerothermics can cost between 12,000 and 16,000 €, depending on the equipment and installation.
Grants and subsidies for aerothermal energy in Spain
Currently, there are several incentives that can significantly reduce the cost of installation.
Main grants available:
- Next Generation EU Grants: Subsidies of up to 40% of the installation cost.
- Personal income tax deductions: Up to 20% deduction in the income tax return for improving energy efficiency.
- IBI rebates: In some municipalities, up to a 50% rebate on the Real Estate Tax for several years.
- Autonomous and local subsidies: Some autonomous communities offer additional subsidies to promote aerothermal energy.
Example of savings with subsidy:
If an installation costs 12,000 € and receives a 40% subsidy, the final price will be 7,200 €, considerably reducing the amortization time.
Comparison of consumption: aerothermal energy vs. natural gas
One of the major benefits of aerothermal energy is its low energy consumption compared to traditional systems such as natural gas or oil.
| System | Estimated annual energy consumption (100 m²) | Approx. annual expense |
| Aerothermal (COP 4) | 3,000 – 4,500 kWh | 600 – 900 €/year |
| Natural gas boiler | 9,000 – 12,000 kWh | 1,000 – 1,500 €/year |
| Oil-fired boiler | 1,200 – 1,500 liters | 1,800 – 2,200 €/year |
| Electric boiler | 9,000 – 12,000 kWh | 1,800 – 2,500 €/year |
- Aerothermics consumes three times less energy than a natural gas boiler to produce the same amount of heat.
- The annual savings can exceed €500-1,000 on the energy bill .
- In 5-7 years, the investment in aerothermal energy is fully amortized with the savings generated.
Long-term profitability of aerothermics
Aerothermics not only reduces the energy bill, but also offers high cost-effectiveness compared to other systems.
Amortization time of the investment
- Apartment with aerothermics (8,000 € investment, saving of 600 €/year) → Amortization in 6-7 years
- House with aerothermal energy (12,000 € investment, saving of 1,000 €/year) → Amortization in 5-6 years
- If a 40% subsidy is received, the amortization time is reduced to 3-5 years.
Factors that increase profitability
- Greater savings if combined with photovoltaic solar panels.
- Equipment life of more than 20 years, with low maintenance.
- Revaluation of the house, since it increases its energy efficiency.
Aerothermal energy requires a high initial investment, but its low energy consumption and the available subsidies make it a cost-effective solution in 5-7 years. Compared to natural gas, the annual savings are significant, and if combined with solar energy, the bill can be reduced to almost zero.
Installation and maintenance
The installation of an aerothermal system requires proper planning to ensure maximum performance and efficiency. In addition, its maintenance is minimal compared to other air conditioning systems. In this section, we will see how aerothermal systems are installed, what aspects need to be considered and what maintenance is required.
How is aerothermal energy installed?
The installation of aerothermal energy varies depending on the type of house and the thermal distribution system. However, the general process consists of the following steps:
Installation steps
- Study of the house: The available space, thermal needs and existing elements (radiators, underfloor heating, etc.) are analyzed.
- Choice of the appropriate equipment: The power of the equipment is determined according to the m² of the dwelling and the DHW demand.
- Installation of the outdoor unit: It is placed in a place with good ventilation (facade, balcony, garden, rooftop).
- Indoor unit installation: It can be a split (separate) or monobloc (all-in-one) unit.
- Connection to the thermal distribution system: Depending on whether there are radiators, underfloor heating or fan coils.
- DHW tank installation: A hot water storage tank is installed if necessary.
- Testing and commissioning: Leaks, temperatures and system settings are checked.
What maintenance does an aerothermal system require?
Aerothermal energy is a low-maintenance system, since there is no combustion or waste. However, there are certain recommended cares to ensure its good performance.
Basic annual maintenance
- Check filters and fans of the outdoor unit to avoid obstructions.
- Pressure and refrigerant check to ensure system efficiency.
- Cleaning of heat exchangers and coils to avoid loss of performance.
- Checking the DHW tank to remove possible lime scale build-up.
Cost of maintenance
Aerothermal maintenance usually costs between 80 and 150 € per year, depending on the company and the type of equipment.
Possible problems and solutions in aerothermics
Although aerothermal energy is a reliable system, some drawbacks may arise.
| Problem | Possible cause | Recommended solution |
| Low efficiency in winter | Very low outside temperature | Check insulation, combine with solar energy or hybrid system. |
| Outdoor unit noise | Obstruction or wear | Clean filters and fans, check supports |
| Low system pressure | Water leakage in the circuit | Check pipes and valves |
| Lack of hot water | Insufficient deposit or activated resistor | Expand tank capacity or adjust temperature |
| Increase in electricity consumption | Inadequate configuration | Adjust thermostats and time scheduling |
To avoid problems, it is important to choose a quality installation and to carry out periodic inspections, but once installed, maintenance is minimal and inexpensive. With basic care and periodic inspections, the system can operate with high efficiency for more than 20 years.
Efficiency and sustainability
One of the main attractions of aerothermal energy is its high energy efficiency and its positive impact on the environment. This system makes it possible to reduce energy consumption and CO₂ emissions, which makes it a key option within renewable energies.
How much savings can be achieved with aerothermal energy?
Aerothermics stands out for its high performance, measured through the Coefficient of Performance (COP) and the Seasonal Performance Factor (SCOP):
- COP (Coefficient of Performance): Ratio between energy consumed and energy produced under optimal conditions.
- Example: A COP of 4 means that for every 1 kWh of electricity consumed, the system generates 4 kWh of heat.
- SCOP (Seasonal Coefficient of Performance): Average performance over an entire season.
Savings compared to other heating systems
| System | COP / SCOP | Annual energy expenditure (100 m²) | Approx. annual cost. |
| Aerothermal (COP 4) | 3.5 – 4.5 | 3,000 – 4,500 kWh | 600 – 900 € |
| Natural gas | 0.9 – 1.0 | 9,000 – 12,000 kWh | 1.000 – 1.500 € |
| Gasoil | 0.8 – 0.9 | 1,200 – 1,500 liters | 1.800 – 2.200 € |
| Electric boiler | 1.0 | 9,000 – 12,000 kWh | 1.800 – 2.500 € |
The aerothermal system consumes up to 70% less than a gas boiler. The annual savings can exceed 600 – 1,000 € depending on the system it replaces.
Aerothermics and renewable energies: combination with solar panels
One of the best ways to boost the efficiency of aerothermal energy is to combine it with photovoltaic solar energy.
Benefits of the combination of aerothermal + photovoltaic:
- It allows to further reduce the electricity bill by generating electricity with solar panels.
- In some cases, the consumption of aerothermal energy can be practically free during sunny hours.
- Decreases dependence on the power grid and price fluctuations.
Real example of savings:
- A house with aerothermal energy and solar panels can reduce its electricity bill by up to 90%.
- If the aerothermal installation consumes 700 €/year in electricity, with solar panels it can be reduced to less than 100 €/year.
Point to consider:
- It is necessary to size the solar installation correctly to cover the needs of the aerothermal system in winter.
Regulations and standards in Spain
In Spain, aerothermal energy is recognized as renewable energy in the Technical Building Code (CTE) and in the European Directive 2009/28/EC, which favors its implementation in new constructions and refurbishments.
Key regulations:
- Technical Building Code (CTE DB HE) → Mandates the installation of renewable systems for DHW production.
- Grants and subsidies → Included in government and EU energy efficiency programs.
- Tax rebates → IBI reduction and IRPF deductions for energy efficiency improvements.
Aerothermal energy is one of the technologies with more regulatory support in Spain, which facilitates its installation and access to economic incentives.
Real cases and opinions
To make an informed decision about the installation of aerothermal, it is useful to know real user experiences, opinions about its performance and comparisons of brands and models available on the market.
User experiences with aerothermal energy
Users who have installed aerothermics highlight its efficiency and energy savings, but also mention aspects to consider before installation.
Most common positive opinions
- Energy bill savings: Most users notice a 40-70% reduction in energy consumption compared to gas or diesel.
- Thermal comfort: Temperature stability in winter and summer.
- Sustainability: Considered an environmentally friendly option by reducing CO₂ emissions.
- Low maintenance: It does not require mandatory annual revisions like gas boilers.
- Compatibility with solar panels: Further increases energy savings.
Most common negative opinions
- High initial investment: The installation cost is higher than that of a gas boiler.
- Space required: One outdoor unit and one DHW tank are required.
- Efficiency in extreme temperatures: In very cold climates (below -10°C), performance may be affected.
- Payback time: Although the savings are high, the investment takes 5-7 years to recover .
Real savings example:
A user with a 120 m² house in Madrid who changed his gas boiler for aerothermal reports:
- Before (with natural gas): 1,400 €/year in heating and DHW.
- After (with aerothermal): 600 €/year in electricity.
- Annual savings: 800 €.
- Amortization in 6 years (considering an investment of €5,000 with subsidies).
Opinions on aerothermal energy in 2024
In 2024, aerothermal continues to gain popularity, especially due to available subsidies and rising gas prices.
Summary of current trends and opinions:
- Increased interest: More and more households are opting for this system due to gas restrictions in new construction.
- More competition among brands: Better prices and more efficient models.
- Impact of solar energy: The combination of aerothermal energy with photovoltaic makes many homes reduce their consumption to almost 0 €.
- Expansion in apartments: More compact options for housing without space for large units.
Comparison of fan heater brands and models
There are several brands that manufacture aerothermal systems, each with different features and prices.
| Brand | Recommended model | COP / SCOP | Price approx. | Outstanding features |
| Daikin | Altherma 3 | 4.5 / 5.1 | 9.000 – 14.000 € | High efficiency, ideal for cold climates |
| Mitsubishi | Ecodan | 4.2 / 4.8 | 8.000 – 12.000 € | Good heating and DHW performance |
| Panasonic | Aquarea | 4.0 / 4.5 | 7.000 – 11.000 € | Good value for money |
| Vaillant | AroTHERM | 4.3 / 4.7 | 8.500 – 13.000 € | Reliable brand, ideal for boiler replacements |
| Fujitsu | Waterstage | 4.0 / 4.4 | 7.500 – 10.500 € | Affordable option with good efficiency |
Tips when choosing a brand:
- If you live in a cold climate, choose Daikin or Mitsubishi for their better low temperature performance.
- If you are looking for a balance between price and quality, Panasonic and Fujitsu offer more affordable options.
- If you already use a Vaillant boiler, its aerothermics can be compatible with existing radiators.
User experiences show that aerothermal is an efficient, sustainable and cost-effective alternative in the long term, although it requires a high initial investment. Opinions in 2024 continue to be mostly positive, with more options on the market and subsidies facilitating its implementation.
