In my diploma thesis I am dealing with an existing energy non-efficient two-storey family house built in the 1970's. The house was built in accordance with the established building regulations at that time, has no thermal insulation, and the main building materials of the construction are natural stone and brick. The purpose of my diploma thesis is to perform an analysis of the constructional physics parameters, energy consumption parameters, and to measure the selected parameters of the indoor climate for the existing condition. I used the measurements of the indoor climate to get real desired values of the existing condition parameters which will be compared to the values calculated by TEDI program. I would like to find out, in what order of magnitude the computational values deviate from the measured ones. I intend to use these data to calculate the energy consumption parameters which I will determine using the TOST program. When calculating the energy usage parameters I focused only on the coefficient's condition of the specific transmission heat losses which is defined in the Slovenian energy-efficient building act (PURES 2010). The heat transmission coefficient will indicate how an existing object deviates from the regulatory requirement. With the intention of improving the indoor climate, thus consequently improving the comfort of living, and from the constructional and physical point of view remedial measures will be proposed based on my findings. I will recalculate the values of the renewed condition using TEDI and TOST programs, and then compare them with an existing condition.