The use of combined production of heat and electric power in the aggregates of Termoelektrarna toplarna Ljubljana representsfrom the point of view of national economy most economical production. This was our fundamental goal we set ourselves while building the network and other sources of energy in the previous years. The arranged diagrams of heat production from 1984 and 1993 respectively show the success of those efforts - the share of simultaneous production increased from 63 percent to 74 percent, the entire production increased by as much as 64 percent.