Solar thermal integration into a district heated small house

According to the EU's objective, all newly constructed buildings should be nearly zero-energy houses since the beginning of 2021. The requirements for zero-energy solutions implicate an on-site renewable energy generation and storage, often including solar. A new model of district heating (DH) substation including solar heating panels and a storage tank was developed using IDA-ICE energy simulation software toolkits. The domestic hot water (DHW) and space heating were heated by solar panels connected to the storage tank and the whole process was simulated throughout the year in Finnish climate. Simulations showed that solar collectors may help to save approximately half of the energy for DHW heating needs whereas the effect on the space heating was marginal. Saving is approximately 200-400 kWh per square meter of the collector area and decreases with increasing of the total collector area. The variation of the storage tank volume does not show to have significant influence on the annual energy gains as long as the required temperatures for DHW are maintained. Solar thermal integration will affect also the return temperature of the primary side which is most visible during the summer time.