District heating (DH) companies deal with serious economic-financial problems during the transition period towards market economics. The paper investigates economic-financial situation of DH companies. Significant difference between heat tariffs and production costs, huge commercial heat supply losses has been identified with the help of simulation mathematical model. All this causes damage for the sustainable energy development. The mathematical model of the heat sector is based on the establishment of info system of the energy sector and may be used as a tool for the assessment and revision of a state policy