Nowadays, energy is becoming more and more important. With the development of society, the demand of energy is also increasing correspondingly. There is 22% of the total energy which is used in building part. A more effective and sustainable energy system becomes necessary due to increasing energy prices and demand. The aim of this thesis is to make an energy survey of this building, evaluating different sources of energy supply and losses in this building. By evaluating, a better thermal comfort is expectedly achieved when having examinations, and a possible saving method is also expected in order to reduce the cost of this system.

 In this project, the building is located in University of Gävle which is surveyed. It has 2 floors. The first floor is underground as a basement. An examination room is included in the second floor. There are a space heating system and heating recovery system ventilation in this examination building.

At first step of analysis, the data of construction, ventilation, district heating and hot tap water were arranged by Mr. Magnus. Secondly, an energy balance had been done, and it helped to make energy input and output more clearly. In energy supply part, the solar radiation is 22.4MWh, the internal heat from people is 1.95MWh, the internal heat from equipment is 5.63MWh and district heating is 184MWh. In energy losses part, the transmission loss is 165MWh, the mechanical ventilation loss is 38.3MWh, the infiltration loss is 8.38MWh and the hot tap water is 2.09MWh. Thirdly, results of calculations were analyzed. At last, the optimization methods were given to save energy. The optimization methods were changing type of windows and improving indoor temperature which influenced the transmission loss part. Another method was reducing operating time of the ventilation system.

Through these optimizing methods, the total energy use is reduced from 214MWh to 179MWh, and district heating is reduced from 184MWh to 149MWh. District heating of this building is supplied by Gävle Energi company, which is able to save 20% cost by these optimizing methods. According to the investment analysis, 19thousand SEK energy is saved per annum.