Values and implications of building envelope retrofitting for residential Positive Energy Districts

Abstract

Most of Europe's building stock is labelled inefficient. This calls for building envelope retrofitting to reduce energy demand and emissions. Positive Energy Districts (PED) aim for urban decarbonisation by generating more renewable energy within the district boundaries than they import from the grid. Such an ambitious requirement needs energy-efficient building stock as a basis. Thus, this work analyses the economic, environmental and grid-related values of building stock retrofitting in electrified PEDs. To do so, this study uses mixed-integer linear programming to compare different optimised PEDs across European climate zones, settlement densities and building standards. Results indicate that retrofitting for PEDs is essential in districts located in colder climates and dense settlement patterns such as in northern European urban areas. Furthermore, building envelope retrofitting benefits energy flexibility towards the grid and reduces CO2 emissions. Finally, this study determines a specific PED retrofitting threshold cost, depending on climate, population density and the electricity tariff. Thus this work unveils essential information about building envelope retrofitting for PEDs during the planning phase.