At present great efforts are being made for the improvement of the efficiency of combined heat and power stations in district heating grids. In the application engineering of combined heat and power stations, there are still unexploited possibilities of increasing the cost-effectiveness of the supply of district heat. For the covering of electric peak loads, heat accumulators allow the temporary electric operation of BHKW-plants (operational combined heat and power plants). The prerequisite for this is to make out a reliable prognosis for the load curves with regard to the heat and electricity which has to be covered. In the paper presented, a new procedure for the prognosis of load curves is introduced.