Assessing the Challenges of Changing Electricity Demand Profiles Caused by Evolving Building Stock and Climatic Conditions on Distribution Grids

The buildings sector in Switzerland accounts for more than 40% of the country’s overall energy demand and CO2 emissions. The predicted future weather conditions, according to the Intergovernmental Panel on Climate Change (IPCC), will even reinforce this trend. Due to the foreseeable further electrification of heating and cooling demand in buildings their electric load demand will likely increase. For these reasons it is essential to reduce the energy demand of buildings, and optimize it by using renewable energy sources (RES) in conjunction with suitable storage elements, such as thermal energy storage (TES). These two factors will, however, drastically change today’s observed “typical” building load demand profiles. Higher peak load demand during cold and hot weather conditions as well as significant PV power production on sunny days will induce new challenges for electric distribution grid operation and planning such as more frequent and higher power spikes. These challenges will be assessed and possible mitigation options, i.e. the usage of storage elements, discussed in this paper. The paper presents the energetic analysis of an office building, the Solar Energy and Building Physics Laboratory (LESO-PB), located in the EPFL campus in Lausanne. The building’s energetic model was realized with the software CitySim, and validated with on-site monitoring for the time period 2011 to 2013. Further analysis shows its thermic behaviour in future climatic scenarios (IPCC model for the year 2100, scenarios B1, A1B and A2). The electrical load demand of the building and the electricity production by the BiPV system can be optimally matched, during the different months and hours of the day, by means of thermal and/or electrical energy storage. This enables the maximization of the building’s selfconsumption from PV power production. An assessment of the challenges for the electric distribution grid due to changing electric load demand patterns is presented for a residential as well as an office usage profile.