CLIMATE COMPUTER ALGORITHMS FOR PEAK SHAVING OF GREENHOUSE HEATING DEMAND

The traditional pattern of energy consumption for heating a greenhouse shows two peaks; one at dawn and one at sunset. When large areas of g reenhouses are supplied by district heating from a combined heat and p ower station these peaks create difficulties for the supply system, be cause the pattern of energy consumption is very similar for all the gr eenhouses. This can affect the power station's ability to meet the sim ultaneous demands for its supplies of heat energy and electrical power at peak periods. Strategies for levelling out the heat energy consump tion of greenhouses are therefore essential in these circumstances. Th is paper deals with the development and testing of computer algorithms designed to spread the energy demand of greenhouses, with consequent shaving of the two peaks. Ornamental pot plants were grown in two gree nhouses, employing a commercial climate computer to control room tempe rature, integrated room temperature, supplementary light and inlet wat er temperature to the heating system. One greenhouse was maintained at equal day and night temperatures, as a reference. The other employed a low day temperature/high night temperature regime (negative DIF). Ph ysiological background to the environmental regimes employed is outlin ed. The negative DIF algorithms developed were able to level out the e nergy consumption peaks - transferring the use of energy to night time - while producing plants of unimpaired quality and unchanged producti on time.