Heat pumps: a versatile solution for low-carbon cities

Europe badly needs to make its buildings more energy efficient: but what if an easy solution would already exist? For over a century, heat pumps hidden in basements, on roofs and in machine rooms, have been saving million tonnes of greenhouse gases emissions each year.

Multiple uses of heat pumps

Their operating principle is simple: they transfer ambient heat from a cool space to a warm space. The heat captured by heat pumps can come from the ground, water, air, or waste heat from industrial activity. In Aachen for example, waste heat from sewage water is used to heat 160 homes in the Northern district of the city.

On top of their ability to use various sources of thermal energy, heat pumps can provide both heating and cooling at the same time, making them a suitable solution for different climates and contexts. Heat pumps are flexible enough to be used for industrial applications, individual houses, building blocks, and in district heating systems, such as in Aachen and Tampere.


For the pumping system to function heat pumps need electricity, which can come from the grid or from renewable energy generated locally. In the case of a building in Bratislava – renovated within the EU-GUGLE Smart City Initiative – solar panels on the roof are used to power the newly installed heat pumps. By using electricity produced on-site, these heat pumps will prevent blackouts and the overloading of the electricity grid in peak times.

The latest models of electric heat pumps can transform one unit of electricity into three to five units of heat. This way, they can cover up to 100% of a building’s heating, cooling and hot water demand. Following the installation of four heat pumps, almost two thirds of the energy consumed by the 42 households living in the aforementioned building in Bratislava now comes from the combined solar panel and heat pump systems.


Providing energy whenever it is needed

Their heat storage systems allows heat pumps to work without any external source of electricity for two to three hours. In times of low electricity supply or blackouts, heat pumps can still use the heat stored previously to keep working.

In Tampere, the EU-GUGLE Smart City Initiative enabled the renovation of eight buildings and the installation of heat pumps connected to a ‘two-way’ district heating network. This system gives residents the possibility to sell the excess energy produced in low consumption periods, or buy energy on the market when the energy produced through heat pumps is not enough for their needs.

“Due to their multiple applications and high adaptability, heat pumps have a considerable potential for increasing buildings’ energy efficiency and renewable energy consumption in Europe”, says Thomas Nowak, Secretary General of the European Heat Pump Association, “Exploiting the unused potential of heat pumps in cities could in fact represent one of the key solutions to reach the European Union’s climate and energy targets”. Within Smart City projects, heat pumps are gaining ground in Europe, making wider replication the next step on the route to a stronger European green economy.

To learn more about the operating system of heat pumps and their benefits, you can visit the website of the European Heat Pump Association, and have a look at their new campaign to help cities better understand the advantages of heat pumps.