Buildings should be front and center in efforts to tackle climate change. Buildings account for 40 percent of global energy demand and a third of all greenhouse gas emissions.
Efforts to renovate buildings to make them more energy-efficient are slowly underway. In a new study published in Nature Communications, researchers from Switzerland take a deeper look at two common renovation strategies: changing the fossil fuel-based heating system and better building insulation.
Their finding: switching to heat pumps or wood pellets, and the use of bio-?based insulation materials such as straw or hemp could slash greenhouse gas emissions of buildings in Switzerland by up to 87 percent.
Routes to decrease the carbon footprint include a host of technologies. Electric heat pumps are promising, and are starting to make headway in Japan, Europe and the UK. Researchers and companies are also developing better cooling technologies, smart windows that save energy use, better paints and coatings, and bio-based insulating materials.
The team from ETH Zürich addresses the question of how to renovate a building so that its greenhouse gas emissions are minimal over its entire lifecycle. They used an AI-based model to identify the best renovation strategies for the most impact. They take into account emissions and cost related to the strategies, but also uncertainties related to the evolution of climate, costs, and user behaviors.
Switzerland has about 1.8 million residential buildings and a further million non-residential ones. For their study, the researchers chose six buildings that have not changed much since they were first built between 1911 and 1988.
Carbon emissions from the manufacture of conventional insulation materials can be high enough sometimes to cancel out the positive effects they have on energy consumption.
So for each building, they calculated the emissions from various renovation strategies over a 60-year building life cycle, starting at the time of the renovation. This included replacing existing heating systems with those powered by gas, wood pellets, or a heat pump. The other strategy they analyzed was conventional insulation materials such as fiberglass as well as bio-based insulation materials made from straw or hemp.
“As the energy consumption of residential buildings in Switzerland is, on average, closely aligned with that of Northern European countries, it makes Switzerland an informative case study for exploring energy retrofitting scenarios in Europe,” the authors write.
Source: Alina Galimshina et al. Strategies for robust renovation of residential buildings in Switzerland. Nature Communications, 2024.