Nowadays efficiency measures are more and more important because the price of the energy is increasing every year. Moreover, saving energy it is also important for decrease the environmental impact.

Kastvallen is a hockey arena built in 1997 that cools the hockey rink with electric compressors. The changing rooms are heating by using district heating. Actually the total invoice of electricity is above the 800000 SEK. Meanwhile the district heating invoice reaches the 60000SEK. The aim of this project is reducing the amount of the electricity and heat invoice promoting smart energy improvements.

The improvements proposals can be divided in three sections; energy savings of the changing rooms, efficiency increase of the compressors and dehumidifier energy savings.

For heat the tap water and the changing room’s ventilation it is suggested to take profit from the heat released at the condenser and so reduce its heat load requirements. For this proposal two different configurations are studied.

In order to increase the efficiency of the compressors the possibility of reducing the condenser temperature will be studied. Three proposals will be studied to carry out this commitment; Installing a condensing temperature control, installing a evaporate cooler and having a snow storage.

Finally, one of the largest consumers of electricity in Kastvallen ice hockey rink is the dehumidifier. The current dehumidifier works with a desiccant wheel. The desiccant material extract the moisture from the processed air flow, after that the desiccant has to be reactivated with ‘fresh air’. This reactivation air needs to be heated 95ºC, so the waste air released after the reactivation of the desiccant is air at high temperature.

The first proposal is preheat the reactivation air with the hot waste air in order to reduce the heating requirements, conducting this proposal the total money saved each year would be 41811 SEK with a Pay-back around 1 year. The second step is studied the possibility of heating the air with district heating, taking into account that district heating is three times cheaper than electricity, conducting this proposal the total money saved each year would be 45629 SEK with a Pay-back around 1 year. The last proposal is to combine preheating and heating with district heating, conducting this proposal the total money saved each year would be 61553 SEK with a Pay-back around 1.6 years.

All the previous energy improvements proposals are studied with empirical and analytical methods and using the knowledge gained during the previous years of studies.

The study concludes that the best proposal for the dehumidifier is combine the preheating and heating with district heating. In addition of the money saved, this measure allows to save 2.71 Tm of CO₂ each year.

For the refrigeration cycle, the study concludes that installing a controlled temperature control is the best option if the price of that is lower than 334726 SEK. If not the best option is heating the rooms and the ventilation with the condenser of the refrigeration cycle. These measures could reduce between 8% and 20% of the total energy invoice plus a considerable reduction of CO₂ emissions. Evaporative cooling and snow storage would be studying after with the data of the first year of the condensing temperature control; if it is installed.