In the first part, the thesis presents legislation that mention a near zero-energy building. Based on the requirements and restrictions of these legislations, I proposed the design of the thermal envelope as well as heating, cooling, and ventilation systems for the Šampionka business facility, located in the vicinity of Nova Gorica. I also proposed a system for the exploitation of renewable energy sources. In the first part of the thesis, I designed three facade sections, which differ in their insulation thickness, thus have different thermal transmittance factors. Since I chose two different types of windows, I had six combinations of thermal envelopes of the building. I conducted calculations of the thermal transmittance of the building envelope with the software tool called Ubakus. In the second part, I did an energy analysis of the mentioned building with the software tool KI Energija and compared the results with the limit values obtained from PURES 2010 and AN sNES. For the analysis, I chose three different heating systems: a water-water heat pump, a ground-water heat pump and a gas-fired condensing boiler, in order to assess the differences between their efficiencies. AN sNES requires that at least half of all the energy consumed in a building is derived from renewable sources on-site or near the site. It turns out that such a share can be achieved by employing a heat pump, which uses aerothermal energy. Such an energy share could not be achieved when heating with a gas condensing boiler. The installation of a photovoltaic system was planned on the building, so that the required share could be achieved. Electricity that was not used for heating, can then be used for illumination or for powering various electrical devices inside the building.