Currently, because of the large use of energy in developed countries, the European Union accepted some targets to obtain some savings in the energy use. A review showed that around 20 % of the final energy use in non-residential buildings in Sweden comes from heating, ventilation and air-conditioning system (HVAC). The main motivation of this project is found in the necessity to move towards a more sustainable buildings, making a responsible consumption of the energy.

The research focuses on the heat recovery unit of the ventilation systems of a shopping centre in Gävle, Sweden. The aim is to assess the reasons generating low energy savings and thereupon, propose some measures to obtain a better efficiency in the systems.

The analisys has performed as follows: studying the systems, facility conditions and operation point. To evaluate the efficiency of the heat recovery, it was necessary to measure the temperature, velocity, and mass flow within the installation using a thermo-anemometer, infrared thermometer and TA-Scope devices. Lastly, all the collected information was considered to achieve the results.

Finally, it has found that leakages generating heat losses and the incorrect airflow running the ducts are the main problem for the low efficiency.

The study concludes that replace the isolation in some systems and make and adjustment of the airflows and fluid in the pipes, help to increase the efficiency. These measures allow to increase as maximum in 24 % the energy savings from the current conditions. To conclude, it has achieved the target of the project increasing the energy savings.