Central heating system is an energy model of heating where heat energy is produced centrally and then distributed to consumers via pipes. Most of such systems in Europe were developed during the 20th century and have evolved significantly since the first generations. Use of cogeneration plants is highlighted in the production of heat energy. They are characterized by the simultaneous production of electrical and heat energy. Heat energy accounts for almost half of the global final energy consumption. 44% of that energy is consumed in buildings. Given that residential buildings are large consumers of energy in general, their energy efficiency is of utmost importance. The problem of old buildings with poor energy efficiency is present throughout the EU and therefore increasing the energy efficiency has become a priority. The application of measures to increase energy efficiency in buildings includes a number of different areas of energy saving opportunities and improves the durability of buildings. In addition to energy efficiency measures in buildings such as improving the thermal envelope and installing PVC joinery, heat distributors are emerging as another energy saving tool. Given that heat distributors in Croatia have caused numerous discussions, this paper explains their role, the installation process, the aspect of energy saving, cost calculation of heat energy and their negative sides. Also, in order to show the effects of energy efficiency measures and heat distributors, a case study was made on the consumption of heat energy in buildings. Case study included three buildings located in Zagreb that implemented different energy efficiency measures. The results showed that the biggest savings in heat energy were achieved by the building that installed heat distributors and then carried out energy renovation.