One of the European Union priorities is the promotion of electricity generated from renewable energy sources. This is due to reasons of security and diversification of energy supply, environmental protection, reducing external dependence of the European Union (EU) in its energy supply and economic and social cohesion.

The members of the EU as a whole, constitute the major world power in what concerns the development and application of renewable energy. The Maastricht Treaty assigned the EU's objectives of promoting sustainable growth respecting the environment. Meanwhile the Treaty of Amsterdam incorporated the principle of sustainable development in the objectives of the EU.

The price support system for renewable energy currently prevailing in the EU is the system Renewable Energy Feed-in Tariffs (REFIT). The geothermal energy is considered as one of these renewable energies, so, it gets benefits from this system.

In the concrete case of Sweden, almost 40% of the energy used is represented by the residential and services sector. So, to maximize the usage of renewable energy in these sectors is a priority for the country. In this way, low enthalpy geothermal energy is the easiest way of using geothermal energy in residential buildings.

In this project it is studied a block of flats in N. Kungsgatan 37-43 (Gävle), whose heating and tap hot water system are handled by a geothermal heat pump combined with district heating. The system has been analysed because the consumption of electricity was higher than expected and this is a problem when the energy saving is the objective.

For the analysis, different elements of the installation have been checked to verify if they are working correctly. For example, if the temperature sensors are giving properly information to the controlling system and the effectiveness of heat exchangers is the correct. The whole installation has also been carefully inspected with a thermal camera to check possible liquid or heat leakages in the machines room.

Finally, after study the heat pump, the conclusion is that the problem is in the geothermal part of the heat pump, because the probes are not able to supply the required heat to the system. This is due to the geothermal installation was designed for another heat pump which was installed in the building some years ago. However, when the new installation was done in 2010, the geothermal installation was not changed for the new heat pump installation.