This thesis presents hospital on Vrazov trg in Ljubljana. Part of the thesis will include field measurements of qualitative/quantitative parameters of the indoor environmental quality and computational simulations of energy use and selected environmental parameters in the building. The objective is to present a variety of solutions for energy performance improvement in therms of quality indoor environment and efficient energy use and the preparation of a report for healthy hospital environment. Used methods involves a combination of systematic literature review, measurements and simulations which are implemented in analysis and synthesis of the collected data. The final step is a result of all previous ones % the engineering technical solutions for the renovation of facilities. Measured results of indoor environmental quality parameters and energy use are identical to computer simulations and extended energy report, in which reveals unsuitably environmental conditions and inefficient use of energy. Results of measurements of indoor air parameters, compared to report, deviate to minimum extent, between 1 % 15 %. Energy used for heating between report (139 kWh/(m2a)) and current state simulation (125 kWh/(m2a)) confirm research statements on high energy consumption among European healthcare institutions. In accordance with findings we inclined proposals for energy reconstruction of external building envelope and quality improvement of internal living environment. On facade we suggest thermal insulation layer of rock wool (thickness 10 cm) and replacement of all existing wooden doors and windows with new ones, rebuild ground floor screed and make thermo isolate unheated loft with rock wool (thickness 18 cm). For improve the internal environment parameters we recommends advanced system for management and maintenance of heating, cooling and ventilation, as well as energy saving and use of renewable energy sources. Because of energy renovation is total amount of energy reduced by 2,4 times. With guidelines for universal hospital design we approach building environment to the general public use. Final recommendations have big useful value for other health facilities, wich covet for thermal renovation and improvment of indoor environment quality.