Switzerland's energy strategy aims for a significant reduction in the consumption of the building stock, from 90 TWh currently to 65 TWh by 2050.
Carbon neutrality – or net zero emissions – has established itself as one of the major objectives of global climate policy. The United Nations recalls that, “ under the Paris Agreement, countries (including Switzerland, ed.) agreed to substantially reduce global greenhouse gas emissions in order to keep the long-term increase in average global surface temperature well below 2 °C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C.”
In Switzerland, this vision is now enshrined in the Climate and Innovation Act, adopted by the people in 2023. To keep our promises, we will not only need to reduce our greenhouse gas emissions, but also remove some of the CO₂ present in the atmosphere.
However, recent analyses have shaken the outlook. According to a study published in “Earth System Science Data” by an international collective of more than sixty scientists, the goal of limiting warming to 1.5 °C now appears out of reach. If global emissions continue at their current pace, this threshold could be crossed irreversibly within three to four years.
A sober finding, which should not, the authors insist, “plunge us into fatalism.” If 1.5 °C can no longer be avoided, the target must now be 1.6 °C. Every tenth of a degree matters: to mitigate heat waves, preserve ecosystems and limit extreme weather events.
The principle of net zero is, on the surface, simple: it is about stabilizing the concentration of CO₂ in the atmosphere by ensuring that no more greenhouse gases are emitted than can be removed.
This balance rests on two main pillars. The first is to reduce emissions at the source, by decreasing energy consumption, improving the efficiency of systems and rethinking our modes of production and construction. The second aims to neutralize residual emissions, that is, those that cannot be avoided, through what are called negative emissions solutions.
These solutions rely either on natural mechanisms — such as reforestation or soil regeneration — or on more complex technologies, such as pyrolysis (transforming biomass into storable carbon), direct air capture (DAC) of CO₂ and its geological storage (Carbon Capture and Storage, or CCS) in deep layers.
But as things stand, these carbon capture techniques remain energy-intensive, costly and difficult to implement at scale. They therefore cannot substitute for reduction efforts: they may complement them in the future, but under no circumstances can they replace them.
In Switzerland, about 45 % of total energy consumption is attributable to the roughly 2.3 million buildings in the country, a large part of which still needs energy-related renovation. The building sector is thus responsible for 33 % of national CO₂ emissions. It therefore represents a major lever for achieving climate neutrality.
And Switzerland is aware of this, since our Energy Strategy aims for a significant reduction in the building stock's consumption, from 90 TWh currently to 65 TWh by 2050. It should be noted, however, that the problem is not limited to emissions related to building operation (heating, electricity, etc.), but also concerns so-called “embodied” emissions, that is, the “hidden carbon” generated by material production, transport, construction and demolition.
“ For new buildings powered by renewable energy, it is even possible that the embodied energy is higher than the operational energy over the lifetime of the building ” specifies the association ecobau, which brings together public project owners and training institutions.
To better grasp what the concept of “net zero” concretely means when applied to the building sector, the Federal Office of Energy (OFEN) launched at the end of 2022 a research project entitled “Net zero greenhouse gas emissions in the building sector.” Its objective: to establish a clear definition, shared by stakeholders, and usable as a reference for future standards and regulations.
The results show that the emissions of a residential building can vary greatly depending on design choices. The project thus highlights significant room for manoeuvre, provided these are considered a priority from the earliest planning stages.
Several concrete levers, deployable from today, have also been identified: reduce living area per person, optimize the compactness of volumes, favour bio-based or reused materials, avoid deep basements (notably for parking) and prioritise renovation over demolition.
In parallel, the report makes thirteen structural recommendations. The most urgent is to introduce binding limit values for embodied emissions. Other measures include integrating life cycle analysis into calls for tender, strengthening carbon databases, adapting SIA standards, training industry professionals and supporting exemplary projects through targeted incentives.
Despite the climate commitments enshrined in Swiss law, the transition to a net zero carbon building stock is slow to begin. One reason is the absence of a truly binding legal framework. The Constitution assigns competence for construction to the cantons, which leads to a wide disparity of approaches and hinders harmonization.
To date, no mandatory national limit values apply to embodied emissions. The majority of current recommendations, whether standards, labels or best practices, remain voluntary. As for the CO₂ Act, although it sets overall reduction targets, it does not specifically target emissions related to materials or construction.
In the absence of clear rules, the most emission-intensive practices continue to predominate. Yet, to hope to reach the targets set for 2050, it is essential to define concrete caps, support stakeholders in the sector and develop effective monitoring tools.
Trajectories toward net zero are not fixed. The Federal Office of Energy (OFEN), through its study “Energy Perspectives 2050+,” explores several scenarios compatible with the objective of net zero emissions by 2050. These variants model different combinations of technologies (renewable energies, storage, energy efficiency), behaviors (sobriety, electrification, renovation) and policy frameworks.
Although these scenarios concern the whole Swiss energy system, they highlight the scale of adaptations needed in the building sector in the face of a rapidly changing environment. Implicitly, they also remind us that the transition does not rest on a single trajectory, but on a collective choice of priorities and ambitions.
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