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Energy efficiency measures in buildings are considered to have great potential for reducing total energy use, and contribute to a reduced climate and environmental impact. In Sweden, however, there is a focus on bought energy, which does not always reflect the environmental and climate impact. Focusing on bought energy means that a house owner may choose an electricity based heat pump instead of district heating (DH), since heat pumps result in less bought energy compared to DH.

The energy system surrounding the buildings is affected by the choice of energy carriers used for heating. This thesis uses three different methods to study how the energy system is affected. In the first part, primary energy use has been calculated for a simulated building with different heating systems, resulting in different electricity and DH demands. The second part studies the impact on peak demand and annual consumption in the power grid and DH system due to different market shares of electricity based heating and DH. In the third part, the life cycle cost is calculated for different heating solutions from both a building and a socio-economic perspective, for 100 % renewable energy system scenarios.

The results show that the choice of energy carrier has a great influence on primary energy use. However, this depends even more on the calculation method used. Which heating solution, and thus which energy carrier, gives the lowest primary energy use varies with the different methods.

The power grid and DH system are affected by the choice of energy carrier. There is a potential to lower peak demand in the power grid by more efficient heat pumps. But an even greater potential is shown by using DH instead of electricity based heating. A larger share of DH also allows the production of more electricity with the use of combined heat and power.

The life cycle cost for different heating solutions also depends on the method used. From a building owner’s perspective, with current electricity and DH prices, electricity based heating is more economical. However, from a socio-economic perspective, with increasing electricity system costs due to a larger share of variable electricity production in a 100 % renewable system, DH becomes more economically profitable in several scenarios.

The choice of energy carrier for heating in buildings affects the energy system to a high degree. A system perspective is therefore important in local, national and global energy efficiency policies and projects.