In the erection planing of new generation capacity, besides the profitability, there is need to taken in account the rational consumption of primary energy, and the environmental protection. The main rules could have cogenerations of the heat and power. In power plant EL-TO Zagreb there are analysed generating capacity of the cogeneration process. There is considered reconstruction and revitalisation`s of existing generating units, and erections of new one, all in the purpose to meet the growing heat demand. The district heating system is considered from the point as opportunity in energy saving capacity in the cogeneration of heat and power. For the amount of the energy saved there is need for less primary energy to be consumed, and this in finally means that for the some energy demands it has the some effect as the natural energy resources are expanded. (author). 9 figs., 7 tabs., 12 refs.