Jokūbas Lukenskas, IGLU TECH Techninių pardavimų kompetencijos vadovas
For many, a heat pump is associated only with heating in winter. However, as heat waves in Europe become more frequent and intense, the question of home cooling naturally arises. The good news is that an advanced heat pump becomes an efficient, year-round home climate system. It takes care of warmth in winter and ensures coolness in summer.
Cooling is becoming increasingly relevant
Modern A++ class homes retain heat exceptionally well. Unfortunately, that’s also true when it’s not needed—during summer heat waves. Because of large windows, airtightness, and insulation, such a house can heat up significantly, especially if not enough attention was paid to cooling in the design phase.
Then most people immediately think of an air conditioner. And that’s quite natural—the heat pump is primarily known as a more sustainable and efficient alternative to a boiler. Still, the situation is changing, and modern systems can do much more: they take comprehensive care of the home’s climate.
Heat pump or air conditioner?
An air conditioner is often a rational choice, especially when you need to quickly cool one or several rooms. This technology is familiar enough, and buyers are also attracted by the appealing cost of system installation.
Still, a heat pump can be an even more logical solution. Modern heat pumps become a centralized system that can heat the house, prepare domestic hot water, and in summer maintain a comfortable temperature in all rooms.
Many are surprised to learn that both ground-to-water and air-to-water heat pumps can cool a house much more evenly and efficiently than a traditional air conditioner. It’s just important to note that the cooling principles of these two systems differ: one operates actively, while the other passively.
How does an air-to-water heat pump cool?
Illustration of IGLU Inuit Mono air-to-water heat pump
This is active cooling, where the compressor produces coolness using electricity. Simply put, the pump works like an air conditioner, except instead of supplying cold air it prepares cool thermal fluid (water).
In winter, the pump collects heat from the outdoor air and delivers it to the home. In summer, the compressor reverses the cycle: heat is taken from the house and expelled outside, while the cooled water circulates through underfloor loops, ceiling capillaries, or fan coils to evenly cool the rooms.
How a ground-to-water pump cools
Illustration of IGLU Aleut ground-to-water heat pump
This is passive cooling, and the principle is even simpler: the system doesn’t generate coolness; it simply draws it from the ground.
At a depth of several dozen meters, the temperature is stable all year round, so in summer an 8–12 °C cool heat-transfer fluid (depending on the boreholes) is supplied from the borehole to the house. The compressor does not run—only the circulation pumps turn, so electricity consumption is minimal: the circulation pump uses only 60–90 W per hour. Thus, only about 2–3 kW of electricity is consumed per day for passive cooling.
What is needed additionally
For the coolness to reach the rooms, it needs a “path.” That becomes the surfaces or devices through which the cool heat-transfer fluid (water) delivers coolness to the rooms. Radiators are usually unsuitable for this: their area is too small, and condensation would accumulate on cold surfaces.
So, in practice, three solutions are used:
- Fan coils. These are compact units with a fan, similar to an air conditioner’s indoor unit (except that cool water, not gas, flows through them). Fan coils cool a room the fastest, because the cool air is blown directly across the cold radiator surface.
- Floor loops. These are the same piping systems that heat the floors in winter and can gently cool them in summer. It’s a quiet, invisible way to cool, best suited for maintaining a constant, even temperature.
- Capillary ceiling system. Tai tankus plonų vamzdelių tinklas lubose, veikiantis panašiai kaip grindų vėsinimas, tik iš viršaus. Vėsa maloniai „leidžiasi“ žemyn, sistema visiškai negirdima ir neužima vietos. Visgi, Lietuvoje ši sistema išlieka sąlyginai brangi.
Another important component of the system is the buffer (accumulation) tank. It is a water reservoir that stores the cooling prepared by the pump and distributes it evenly. The tank allows the pump to operate steadily without frequent starts and stops—so the system works more efficiently and lasts longer.
A concrete example
A++ class 120 m² home typically requires about 6 kW of heating capacity—based on this, the heat pump is selected. In such a house, either an air-to-water or a ground-to-water system can be installed.
The main efficiency indicator of a heat pump is COP (coefficient of performance) – it shows how many kilowatts of heat the pump produces from one kilowatt of electricity. SCOP is the same indicator, but calculated for the entire season.
Let’s compare two IGLU solutions that are suitable for both heating and cooling:
| Criterion | IGLU Inuit Mono (air-to-water) | IGLU Aleut (brine–water) |
|---|---|---|
| Heat source | Outdoor air | Ground (boreholes or collector) |
| Heating efficiency | COP 3.8–4.5 (SCOP ~4.0) | COP 5.5–6.5 (SCOP ~6.2) |
| Cooling method | Active – cooling is produced by the compressor | Passive – natural ground cooling |
| Cooling electricity consumption | Lower compared to a traditional air conditioner (1 kW electricity → 4 kW cooling) | Minimal – only the circulation pumps run (1 kW electricity → 15 kW cooling) |
| Installation complexity | Medium – an outdoor unit and an indoor distribution system, no earthworks needed | Complex – requires vertical boreholes or horizontal collectors |
| Installation cost | Medium initial investment. The price of equipment and work is usually from 7 to 15 thousand EUR. | Higher upfront investment. The cost of equipment and installation typically ranges from 15 to 35 thousand euros. |
| Durability | ~15–20 years | Pump ~20–25 m, borehole – 50+ m |
| Who it suits best | For homes without the option for boreholes, smaller plots, a faster and cheaper start | For those building for the long term, aiming for the lowest bills and the cheapest cooling |
Most important – an individual approach
Every home and its residents’ needs are unique. The most suitable solution (a traditional air conditioner, an air-to-water heat pump, or a ground-to-water heat pump) should be determined by an individual assessment of the property. The choice depends on the home’s size, the plot/ground, the building’s construction, the building’s thermal resistance, the planned budget, and installation timelines. Therefore, it’s worth deciding based on what your home actually needs. It’s important to do this together with specialists already at the design stage.
