“…In the Czech Republic, both heat cost allocators and thermal regulation valves are required by law in dwellings served by district heating [80], [81]. In Hungary and particularly in Serbia, the lack of heat cost allocators means that a significant portion of such dwellings are overheated, wasting energy [40], [82], [83]. In Serbia, bad ventilation habits are frequently observed in collective housing units during the heating season and low outside temperatures, especially long lasting ventilation with tilted windows and a fully opened radiator valve [74], [82], [83].…”