The buildings we live and work in are changing – becoming smarter, more efficient, and powered by cleaner energy. But while we’ve made strides in reducing operational emissions, there’s a hidden carbon footprint that remains largely overlooked: the emissions locked into the materials themselves. A recent study by Xiaojin Zhang and colleagues explores how advancements in key sectors could influence the embodied emissions of Swiss residential buildings.
Until now, the primary focus of research on the building sector’s greenhouse gas (GHG) emissions has typically been on the energy a building consumes while in use. This focus ignores the growing contribution of embodied GHG emissions by the construction materials. Every brick, steel beam, and layer of insulation has embodied greenhouse gas emissions, and as buildings become more energy-efficient, these emissions could soon account for much of their climate impact. A recent study by Xiaojin Zhang and colleagues explores how advancements in the electricity, cement, and steel sectors could influence the embodied emissions of Swiss residential buildings from 2015 to 2055.
Embodied emissions of construction materials
In Switzerland, the construction sector plays a crucial role in reducing GHG emissions, as buildings account for a significant share of the country’s total emissions. Worldwide, the building and construction sector was responsible for 25% of GHG emissions in 2021, including both operational and embodied (mostly in the form of construction materials) emissions throughout the life cycle of buildings. With many technological advancements and energy efficiency measures on the horizon, to what extent can we expect these emissions to decrease the embodied emissions of construction materials?
The authors find that future global advancements in electricity and major industrial sectors can reduce the embodied GHG emissions of construction materials in Swiss residential buildings by up to 25% by 2055 – but only under the most ambitious climate scenarios. “Something surprising we learned is that the reduction in material consumption seems to have a greater impact on decarbonizing Swiss residential buildings than the advancements in material manufacturing considered in this study,” says Zhang.
Concrete and brick biggest contributors to lowering emissions
Concrete and brick production are identified as key drivers of emission reductions, benefiting from cleaner energy and material efficiency improvements in manufacturing, and a decline in their consumption as the building stock shifts toward more renovations and fewer new buildings in the future. By 2055, concrete will experience an up to 60% reduction in GHG emissions in its production stage; brick up to an estimated 20%.
Wood products exhibit a broad possible range of emission reduction potential, but their impact on reducing the embodied GHG emissions of the building stock remains limited – likely due to their relatively low consumption. Meanwhile, insulation materials are expected to contribute increasingly to embodied emissions due to rising building renovations.
It is also important to note that, currently, roughly two-thirds of the embodied GHG emissions of Swiss residential buildings are generated outside of Switzerland. Thus, sustainable procurement practices are crucial for minimizing imported GHG emissions.
Open-source life-cycle assessment
The study introduces an open-source, reproducible LCA workflow, providing a framework for stock-level assessments using national or regional LCA databases for construction materials. It also highlights the need for integrating systematic global sectoral foresight into decarbonization strategies to guide policymakers in the built environment.
Zhang et al.’s findings suggest that future technological developments could reduce GHG emissions from construction materials by up to 25% by mid-century for the Swiss residential buildings. This remains insufficient if we want to achieve the net-zero goals from a life cycle perspective. The authors write that, ultimately, a holistic decarbonization strategy that combine not only technological advancements, but also circular economy strategies, alternative materials and innovative construction methods that possibly reduce the consumption of construction materials, will be needed to fully decarbonize the sector.
Original Publication
X. Zhang, N. Heeren, C. Bauer, P. Burgherr, R. McKenna, and G. Habert
The impacts of future sectoral change on the greenhouse gas emissions of construction materials for Swiss residential buildings
Energy and Buildings, 15.01.2024 (online)
DOI: https://doi.org/10.1016/j.enbuild.2023.113824