Optimized heat for areas with low-energy buildings
IIn the OptiHeat-LEB project four main heating technologies in areas with low-energy buildings (LEB)s were investigated and their impacts on costs and the design of energy systems in the long term at local and national level were investigated. Moreover, carbon dioxide (CO2) emissions impacts of the heating techniques were analyzed with an international perspective.
The project was run by IVL Swedish Environmental Institute in collaboration with energy companies, housing companies and the construction industry line association. The goal was to develop knowledge as a basis for planning new areas with low-energy buildings so that the most climate-smart and cost-effective heating solutions are used. For the assessment two energy system optimization (TIMES) models were developed and applied.
The four heat supply options studied were:
- individual heat sources for each property
- small-scale low-temperature district heating (DH) network (local heating network)
- a heat connection to an existing, nearby, larger district heating system
- a combination of district heating and individual heat sources with the possibility of also supplying heat from the building to the district heating network (prosumer).
Our analysis showed that, at the local level, the small-scale low temperature DH option had the least cost of heat supply to LEB areas. It also associated with less total CO2 emissions in the Nordic’s climate policy scenario of carbon neutral energy system by 2050. Non-existence of low-cost heat sources in the vicinity of LEB areas makes the heat connection to nearby low-temperature DH system more cost-efficient than the small-scale DH. This is due to the economy of scale and the low-cost DH technologies characteristic of larger DH systems in Sweden. When LEBs are allowed to become prosumers, the cost of the heat connection to nearby DH system can decrease due to prosumers’ excess heat supply to the DH network during summer and winter days. Finally, the individual heat supply option has the highest cost of heating LEBs in most of the cases.
At the national level, our model results showed that the least cost heat supply option to LEB areas (i.e., small-scale low temperature DH) can reduce electricity use for buildings’ heating as well as system cost of all the energy sectors in terms of achieving Sweden’s goal of carbon neutrality by 2045.
Finally, this work confirms the importance of a wide system boundary, including not only the buildings or building areas, but also the nearby urban areas’ DH systems, when addressing optimal heating of LEB areas.