Demand side management in the district heated buildings to optimize the heat production

The target of this research was to determine the demand side management (DSM) potential for the district heated residential block buildings in order to cut the heat consumption peaks by the short-term heat storage. Daily heat load variations occur due to the social factor of the consumption. The targets of the DSM in the district heating system are to cut the use of the peak production units which usually are heat-only-boilers fuelled with fossil fuels. The case study was done in Helsinki, Finland where the share of the residential block buildings from the total building area is 44 % and where 94 % of the apartment houses are connected to the district heating system. The potential of the heat reduction in residential block buildings was calculated by simulating eight block buildings built in different decades. The simulations were done with the IDA-ICE simulation program. The heat was cut for one hour in the morning peak at 7 a.m. The requirement of the heat cut was that the inside temperature in the block buildings could not decrease over 1 °C. The heat for hot water was not cut. The simulations illustrated that the short term heat storage capacity of the residential buildings built in different decades varied greatly. The buildings built from 1940 to 2002 suits best for the purpose of the DSM because for those buildings the heat demand is high and the buildings store heat well. The indoor temperature of the buildings built before 1940 cools down over 1 °C already when the outdoor temperature is lower than zero (varies for different buildings). Results show that the theoretical potential for the DSM of the residential block buildings in Helsinki was approximately 1% of the total district heating energy supply of the company, using the data of the year 2012. Considering the momentarily heat effect, the significance was much larger, even 80 %. The future work will comprise of the optimization of the energy system with the DSM to demonstrate the energy efficiency potential.