ECONOMICALLY OPTIMAL HEAT SUPPLY TO LOW ENERGY BUILDING AREAS

Paper in proceeding, 2016

European Directives and Swedish national goals aim at increasing buildings’ energy efficiency. The construction of low energy building (LEB) areas in Sweden has increasingly attracted attention due to national support. Compared to conventional buildings, LEBs require little space heating during the cold seasons. Still, there are various options for supply of the required heating. Thus, this study aims at comparing the long-term system cost of three heat supply options to a hypothetical LEB area assumed to be located close to an urban area: an “individual” (i.e. separate heat supply), an “on-site” (i.e. local district heating (DH) system) and a “large heat network” (i.e. heat production in a nearby DH system and transmission to the LEB area). A dynamic approach is applied allowing the heat supply system to develop with time, and an energy system model being able to account for the interactions between the building, heat and power sectors, is utilised for the calculations. Two climate policy scenarios are applied to address the uncertainty in future energy prices etc. A systematic sensitivity analysis is designed to investigate the threshold for cost-effectiveness of the large heat network option compared to the other two options. The sensitivity analysis takes into account different combinations of three key parameters: plot ratio of the LEB areas, specification of nearby DH, and distance between LEB area and nearby DH system. The results show, for most of the tested combinations and under both scenarios, that heat supply from the nearby DH system has the lowest system cost if the distance to this system is no more than 2 km, because of the low-cost sources of heat available in the large DH system. A local DH system is more cost-effective than individual heating of buildings even in a LEB area, if it is densely built.