A LOGICAL NEXT STEP IN A PROVEN COOPERATION
To close this gap, energie-cluster.ch, a Swiss network of public and private organizations working on the country's energy transition, is being co-funded by the Swiss Federal Office of Energy (SFOE) and the Toni Piëch Foundation. It builds on a prior cooperation between the three partners in 2024, when energie-cluster.ch developed practitioner-oriented Key Performance Indicators (KPIs) that architects, planners, and construction professionals can use to compare projects and learn from existing case studies. Those KPIs were implemented on best-practice platforms such as "Aus Alt Mach Neu", which show before-and-after metrics for retrofit projects. That first project moved these platforms beyond looking at operational energy savings alone by adding indicators for whole-life carbon emissions, environmental impact, and circularity. In this second cooperation, a further set of KPIs is being developed to close the blind spot that even whole-life, per-area figures leave open, complementing area-based KPIs with per-resident measures. Working from Swiss retrofit case studies, the network has brought together a working group from small and medium-sized enterprises, academia, and research institutions to build a calculation tool for per-resident CO₂ emissions. The tool will be presented and discussed at a forum for architects and planners in late 2026, then shared through the channels of energie-cluster.ch and its partners.
BACKGROUND: WHY PER-AREA ALONE CAN MISLEAD
In 2023, Swiss voters backed the country's commitment to reach net zero by 2050, which demands major cuts in the building sector. Lowering a building's emissions is complex, because a building carries two kinds of emissions across its full life cycle. Embodied emissions come from producing, transporting, installing, and replacing its materials and building systems, and most of them occur upfront, before the building is occupied. Operational emissions add up year after year, from heating, cooling, and electricity.
A retrofit spends some extra embodied emissions now so that lower operational emissions repay them over the years that follow, improving the building's "emission trajectory" over its remaining life. It usually extends the building's life as well, avoiding the far larger emissions of demolition and new construction. Both kinds rise and fall with the size of the building, so dividing them by floor area sets that size aside and lets different buildings be compared on the same scale.
That is why the standard KPI is reported per square meter, often per year (in Switzerland, kg CO₂-eq/m²·year). This comparison is easy to read, but for retrofits it hides two things. First, when a retrofit adds floor area, for example by adding another floor, the per-square-meter value can still fall even if total emissions grow. Second, the per-area value does not reflect changes in occupancy. When a retrofit ends up serving fewer people than before, emissions per resident climb sharply, a pattern common in renovated rental apartments that become too expensive for their former tenants, with fewer new occupants moving in. In both cases the project's per-area figure improves while the real emission trajectory of the Swiss building sector does not, leaving its climate targets no closer.
HOW THIS FITS TPF'S STRATEGY
This work sits within the foundation's priorities on the built environment and the energy transition, and it connects to related TPF grantees such as Bauhaus Earth, CORRECTIV, and the HouseEurope! initiative. For readers who want the fuller picture of how construction can lower its carbon, from building sufficiency to biobased materials and the reuse of what already stands, Bauhaus Earth's Building for the Future Series gathers those strategies and the evidence behind them.
The Toni Piëch Foundation is co-funding energie-cluster.ch with a grant of CHF 5,000.
