As part of this graduation thesis I examined the impact of different energy remedial measures on energy efficiency indicators in the case of the selected residential building and considered the current method of classification of buildings in the energy classes. I calculated the values of energy indicators with the help of software tools TOST. First I calculated the values of the energy indicators in the exisiting (initial) state. In doing so, I took into account three energy sources for heating - heating by extra light fuel oil, by biomass and by electricity (heat pump). I considered different types of efficiency for each type of aforementioned energy sources because I wanted to check the influence on the efficiency of particular heating systems. Then I chose the most efficient energy remedial measures and used them in the recalculation of energy indicators. I compared the results with results at the initial state. I have found that energy remedial measures affects on the reduction of all four energy indicators (heat required annualy, annual input of energy, annual primary energy and CO2 emissions). The choice of energy source does not only affect on the annual need of energy for heating. Because the
current system of classification of buildings is created only on the basis of thevalue of the necessary energy for heating and it does not include the influence of the choice of the energy source, I made two versions of the mprovements for complementing the existing method of classification.