Possibility for Positive Energy Retrofit in Borlänge

The built environment accounts for 40% of annual carbon dioxide (C02) emissions. Among the total emissions, building operations generate approximately 27% annually. Other than this, building materials, infrastructural materials, and construction (embodied carbon) contribute to an additional 13% annually [1]. C02 emissions to the environment account for global warming and contribute to climate change. In response to the environmental problems and in line with the objectives of the Paris Agreement, the European Union is committed to developing a sustainable, competitive, secure, and decarbonized energy system by 2050. The goal of decarbonization in building stocks is already set to be achievable this year. To achieve these set objectives, it is necessary to shift to the usage of renewable energy in the building industry and also technologically improve measures to reduce energy demand in building stocks which will reduce carbon footprints. In line with the Energy Performance of Building Directive (EU 2018/844), it is stated that one of the applied measures from the year 2021 will be that all new buildings and deep renovations should be at least a nearly zero energy building (NZEB) standard. But in this context of research work, positive energy building (PEB) through retrofitting is the goal. PEBs contribute to the EU’s target for decarbonization of the energy supply and a shift from fossil fuels to Renewable energy sources (RES) [2]. This thesis aims to study the possibility of achieving a PEB in the existing cluster of two-storey multifamily apartments by analyzing its detailed energy demand and its Solar PV production capability. The result is to contribute to the body of knowledge of the SOLVE theme 3 research members. The project location is at Rymdgatan, Petter Blåders väg, Borlänge, Sweden. The building stock has a total of 80 residential units and other ancillary buildings on a land area of 4,682 m2 . IDA ICE 4.8 software by EQUA was used in simulating the annual energy demand in the building envelopes when retrofitted with different energy-efficient measures. The 5.0 beta version of this tool was used to simulate energy production from the solar PV system. The base case shall be by using the district heating energy system and other energy carriers shall be by using the ground source heat pump borehole, heat recovery ventilation system, and the addition of solar PV system. In the base case, the total simulated annual energy demand was 492 MWh with the pre-condition of opening windows during summer and using an external window shading technique for thermal comfort indices to be kept at a very a good level. Retrofitting by changing the window glazing type and by adding extra insulation to the internal walls also provided a very good energy saving procedure. With these, an annual energy demand simulated for the Rymdgatan housing cluster reduces to 409 MWh/year. In another scenario, the heat pump replaced district heating as the energy carrier. With this, annual energy demand was reduced to 208 MWh with an increased primary energy number. With a heat recovery ventilation system, annual energy demand is further reduced to 205 MWh/year. Using IDA ICE 5.0, the main building´s roof area of 1,900 m2 generated 247 MWh of DC power from solar PV annually when tilted at an angle of 150 . This on-site energy generation with a heat pump and heat recovery system made the Rymdgatan housing cluster to be self-sufficient in energy balancing with a total surplus energy of 14% when heat pump is used and 20% if heat recovery system is incorporated into the system. The perspective of decreasing the set-point temperature by 10C from the acceptance value of 210C in the base case results in annual energy being improved by 5.7% while with a ground source heat pump system it was 4.6% for a chosen built model type A