“The problem of heat has been underestimated by real estate players in Switzerland”

Over the past decades, the main concern of the real estate sector was focused on a single objective: protecting against the cold during winter. “When I took my training in the 1990s, we were taught to insulate against the cold. We had not yet been confronted with these overheating phenomena,” explains Stéphane Emery, co-president of Architects for the Climate, in the pages of the daily 24 Heures.

Today, it is clear: Switzerland is warming! It is even warming faster than the global average. At the end of 2025, MeteoSwiss and the Swiss Federal Institute of Technology Zurich indicated that warming relative to the pre-industrial era already reaches 2.9 °C in Switzerland, compared with 1.3 °C worldwide. For the existing building stock, the consequences could be considerable, with part of the housing stock potentially becoming uninhabitable in summer without measures to protect against heat.

In response to this trend, combating heat is logically becoming a major concern. This reality was notably highlighted during a panel of experts dedicated to this topic, organized as part of the Real Estate Meeting 2026, which was held at the Swiss Federal Institute of Technology in Lausanne at the end of March. It was the perfect opportunity to put the microphone to several industry players to delve deeper into the issues. A series of interviews begins with Ludovic Pommiès, project manager and ESG lead at Fundim.

Has the issue of urban heat been underestimated for too long by property developers?

The main focus of developers, as well as of all players in Swiss real estate, long centered on winter comfort, which was logical in a climate historically marked by cold. Summer comfort was not ignored, but it clearly remained secondary, especially since heatwave episodes were rare.

What has changed is the intensity and frequency of periods of high heat. This development has revealed the limited capacity of our buildings to cope with high temperatures. This concerns, of course, the older stock, but also recent buildings that perform very well in winter — notably in reducing heating needs — but are vulnerable to summer overheating.

So yes, one can say that this issue was underestimated, mainly out of ignorance of how the Swiss building stock behaves in the face of high heat. Much of the effort was primarily directed at winter comfort, with the aim of reducing energy consumption in winter and, consequently, the emissions responsible for the warming we are experiencing today.

What about today? Is this aspect taken into account for every new development financed by Fundim?

It is clearly a criterion fully integrated into all our considerations, whether for new projects or renovations. We no longer speak only of energy performance, but of overall climate performance. This issue has become an essential criterion of quality and comfort for tenants, as well as a key risk management factor for investors.

Do you observe concrete consequences on the value of a property poorly protected against heat, and an increase in complaints?

Yes, we are beginning to see concrete signals. First from occupants, with more frequent feedback about summer discomfort, even requests for adaptation. Then, from a value perspective, although the phenomenon is still emerging, a building prone to overheating can become less attractive, harder to rent, or require corrective investments. There is also a legal risk, notably linked to the notion of a housing defect, which can be invoked in some cases. This factor is not yet dominant today, but it is clearly becoming so.

The issue is therefore not so much to oppose passive and active approaches as to combine them intelligently, prioritizing the building’s design above all.

Between so-called “active” or “passive” cooling, what concrete solutions exist to reduce the effects of urban warming on buildings?

There is today a wide range of solutions, but these must be prioritized. Passive solutions always constitute the first response: solar shading, night-time ventilation, thermal mass, greening. They are generally the most effective and durable, both climatically and economically. Active solutions, such as air conditioning or certain cooling systems, act as complements when passive measures are insufficient, or in specific situations.

The issue is therefore not so much to oppose passive and active approaches as to combine them intelligently, prioritizing the building’s design above all. This approach is particularly essential in renovation projects, which must be conceived globally: partial interventions, such as replacing only the windows, can indeed degrade summer comfort.

Is it ultimately more difficult to reduce nuisances related to heatwaves than those associated with severe cold?

Indeed, it proves more complex. Cold is a phenomenon that has long been mastered, for which proven and available technical solutions exist. Heat, on the other hand, is more difficult to manage because it depends heavily on the building’s design, its environment, and its uses.

Once a building has accumulated heat, it becomes much more difficult to regain comfortable conditions without consuming energy. This fight against heat therefore requires greater anticipation and an even more holistic approach, since the challenge also remains to continue protecting against cold in winter.

How do you assess the financial needs to refurbish the existing stock and should we fear that these needs will contribute to increasing rents that are already unaffordable in some Swiss cities?

As mentioned earlier, adapting the existing stock to climate change often involves carrying out full renovations, and therefore significant investments. The central question does not lie solely in the amounts involved, but in how they are financed.

If these investments are poorly structured, they can indeed put upward pressure on rents, as well as on the financial capacity of property owners, particularly private actors. The real risk, however, is not so much to invest as not to do so, because inaction can lead to even greater costs in the long term.

In this context, Fundim — whose portfolio is recent and designed with summer comfort in mind — has developed a solution to facilitate the financing of renovations. It is based on arrangements using rights of superficies, allowing rapid investment while avoiding a direct pass-through to tenants as well as to owners’ incomes.

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