The final thesis is focused od the experimental metods in energy rating of building. In the first part is described history of energy rating from the eigtheens to the present and described is the current trend of energy rating in terms of energy performance certificates. In the second part is elaborated energy assessment for apartment building from bricks with six residential units. For the building is drawn a total of 6 measures, of which there are 3 structural and 3 for building equipment. The measures are assembled to variants and the resulting variant is recommended, including recommendation. In the last experimental part is described the influence of shading elements on the thermal load of the room and modeled the effect of insulating double glazing and triple the overall energy performance reference room.