Climate neutral renovation solutions for the Swiss building stock: How can the Swiss multifamily building stock meet both carbon budgets and energy targets for 2050?

Abstract

Buildings are significant energy users. The main applications of energy in residential and commercial buildings are heating and cooling. According to the Federal Office of Energy, the building sector is responsible for around 40% of Switzerland's energy demand, with residential buildings contributing to nearly half of it. Consequently, they account for more than 30% of the CO2-equivalent greenhouse gas emissions. As we strive to reduce buildings' energy demand, the importance of embodied energy and embodied carbon in building materials has become increasingly apparent, as highlighted in the recent IPCC report. Current renovation practices focus primarily on reducing heating energy demand. Some common solutions include replacing the heating system, improving the envelope with thick insulation, and replacing windows. These kinds of measures implicitly reduce energy demand and, therefore, operational emissions. However, the greenhouse gas emissions generated during material production are often neglected. The goal of the study is to understand which are the most effective renovation measures that will help the Swiss multi-family building stock meet both carbon budgets and energy targets for 2050. This will be accomplished by examining a set of renovation options using an optimisation framework on six buildings representing different construction periods. The research shows that the 2050 Energy goal can be quickly met. It might be accomplished with a mix of heat pump installation and conventional insulation materials at the existing renovation rate (1%), or without replacing the heating system but with an increased envelope renovation rate. However, despite the use of advanced refurbishment methods, wood pellets boiler and bio-based materials, and a renovation rate of 6%, it is still insufficient to meet the 1.5°C budget.