Changing from district heating to a heat pump solution in multi-family buildings is increasingly common in Finland and other Scandinavian countries. This is mainly driven by lower costs. But also decreased GHG emissions due to improved overall efficiency, reduced distribution losses and possibilities for a less carbon intensive energy source is an important factor. This article presents three Finnish examples of this trend.
The first example regards a 6-story residential building in the city of Jyväskylä. An exhaust-air heat pump was installed in January 2013 and connected to both the heating and the domestic hot water (DHW) circuits. The interest in recovery of exhaust air has grown recently, due to increasing prices for district heating. Also, the reported savings in pilot installations, with high return of investment, have been received positively by the market. For this project, energy costs have decreased with 35% and the return on investment is 16% per year. In parallel to this, the overall net energy consumption has decreased by 37% and the annual CO2 emissions by 60 tonnes.
In the second example, ground source heat pumps were installed in Raisio, serving 90 apartments. The decision was driven by the intention to keep housing costs down, despite annual increases in district heating costs, so that the residents could still afford living in their homes. Such a change had not happened in Raisio before, and others even suspected the calculations to be incorrect. The ground source heat pumps were connected to nine geothermal wells, each 230 meters deep. They provide space heating and DHW, and there is also heat recovery from the exhaust air. According to calculations, the payback time of the geothermal system is about 9 years.
The third example, a project in Espoo, describes a change from district heating to geothermal energy. The two 7-storey buildings, containing nearly one hundred apartments, are now equipped with ground source heat pumps with 12 deep ground sources. The idea met initial scepticism and it took some years before the necessary decisions were taken. With the installation work beginning in October 2016, the system has operated flawlessly almost from the beginning. During the actual switch between the heating sources, there was a break in the hot water supply, but only for a few hours. For financial reasons, the project was implemented together with an energy service company (ESCO).
In other countries, there is a growing tendency towards collective systems for new buildings and district heating for existing buildings, often in densely populated areas with social housing. But this might not be in the best interest of the residents. As these examples from Finland show, heat pumps may offer an economically more advantageous alternative.
Jussi Hirvonen, Finland (SULPU)
Onno Kleefkens, The Netherlands (Phetradico)