At the time of writing this, Europe is grappling with an unprecedented heatwave. The extreme climatic conditions have forced school closures and disruption of public services in France, a sanctioned ban on outdoor work in Italy, power outages and several heat-related health fatalities across the region. Exacerbated by the anarchic conditions, Spain, Greece and Turkey are battling wildfires and ongoing droughts. The World Meteorological Organization (WMO) notes that this intense, extreme heat has established a new ‘normal’—and not just for Europe—with global temperatures predicted to exceed pre-industrial levels by more than 1.5°C in 10 years. Apart from resulting in increased natural disasters, soaring temperatures mean that conventional climatic zones are transforming as well. In 2023, former French Minister for Ecological Transition, Christophe Béchu, noted that France must prepare for a +4°C increase in average temperature by the year 2100. To put it simply, the region’s built environment is not adapted to this exceptional state. This provocation underpins 4° Celsius Between You and Me, the main exhibition for the third edition of the Île-de-France Architecture and Landscape Biennale (Bap! 2025), situated in Versailles.

Co-curated by Philippe Rahm, principal architect of Philippe Rahm architectes and Sana Frini, Tunisian architect and co-founder of Mexico City-based LOCUS, the exhibition unravels the central role of architecture in addressing the new climate realities of France and, apropos that, the world at large. The showcase hopes to position itself within an emerging discourse that champions traditional systems and vernacular architecture in rethinking architectural processes, moving away from the technological crutches of HVAC as a ‘solution’ for the heating planet. “We have to renew the catalogue of solutions currently in use in temperate climates. It's no longer viable to build the way we used to in France or Switzerland,” Rahm tells STIR, in a conversation stemming from the urgent themes of the exhibition.

For the showcase, the curators consciously selected participations with practices situated in sub-tropical climatic zones, underscoring contextually grounded design philosophies as future paradigms for architecture. In this, the exhibition’s objective is to incite thinking about alternatives to conventional methods of construction that are based on overt resource extraction and are major contributors to CO2 emissions (roughly 38 per cent globally). Conceiving an architecture that does not enjoy the comfort of HVAC systems, the exhibition confronts its visitors with the possibilities of a world after mechanical heating/cooling.

Housed in École Nationale Supérieure d’Architecture de Versailles (ÉNSA Versailles), the breadth and diversity of practices at the Biennale, their philosophies and ways of working within the climate crisis are especially notable. These include both emerging and established voices within contemporary discourse, including Bogota and Boston-based Alsar-Atelier, Ahmedabad-based Sealab, Bahrain and Kuwait-based Civil Architecture, Chinese practice LUO Studio, Ecuador-based Natura Futura and Senegal-based Worofila. While a majority of presenting practitioners offer diverse perspectives from the Global South—a very necessary inversion in the demography of participations in conclaves of this nature—studios from the Global North who have been exacting in their critique of architecture’s negligence of global warming are also included, such as Barcelona-based H Arquitectes, Andrés Jacques / Office for Political Innovation and Spanish designers Takk.

The exhibition, which directs the attention of the discipline—and its complacency in the face of the climate crisis—to the urgency of the issue, is a vital interjection in the usual yearly roster of design festivals. By focusing on the built narratives of the Global South that have invariably centred climatic considerations for millennia, the exhibition makes ample room for critique of the Global North’s extractivism and for shifting the understanding of comfort. It’s also worth noting here that the focus on traditional architectures of sub-tropical regions (many of which were former colonies of Europe) reveals the implicit discord of who has historically been afforded ‘comfort’ and whose ways of being have so far been dismissed. That climate should become an essential ‘building block’ for architectural design—an idea provocative in its very banality—is an argument Rahm has espoused for decades. The Swiss architect has constructed a critical practice based on what he terms ‘climatic architecture’, attempting to extend the discipline’s parameters from the physiological to the meteorological.

Rahm’s climatically-oriented philosophy, grounded both in research and sustainable design practice, has been part of several biennales and expositions over the course of his career. The conceptualisation of an architecture based on physiological characteristics was born from Rahm’s contribution to the 8th Venice Architecture Biennale with the national pavilion for Switzerland, Hormonorium. With the display, Rahm hoped to highlight the phenomenological aspects of the spaces we occupy, arguing against using only representations as a tool for thinking about architectural culture. Expanding on these principles since 2002, Rahm’s crusade against architecture’s futility in addressing global warming has manifested in a concern with the 'voids' of architecture (using design tools to manipulate what is typically immaterial in interior environments) as opposed to the solids (surface treatments, material memories or structural mass). To this end, the architect and theorist has developed building concepts that centre laws of physics—convection, conduction, radiation, evaporation, digestion, pressure—in conceiving architectural form.

His theses have been expanded on in two recent books as well: The Anthropocene Style (2018) and Climatic Architecture (2023). In these texts, Rahm draws a thread from historical instances of building to the present, arguing that architecture and urbanism have traditionally been based on climate and health and should be re-oriented to centre thermal comfort in our contemporary world. While the more recent Climatic Architecture offers a compendium of the studio’s projects, The Anthropocene Style delves into a critique of the minimalism espoused by modern architecture and its subsequent need to rely on mechanical heating and cooling. As the Swiss architect posits, the ornate interiors were ways to maintain heat within interior environments. The book, which he calls a manifesto for restoring materialism to interior design, includes a catalogue of experimental materials that the studio has developed and displayed in various design fairs over the years. For instance, Façade Emissivity Clothing—showcased at the 2017 Chicago Architecture Biennial and Seoul Biennale of Architecture and Urbanism—acts as a barrier to external heat radiation by virtue of the material used, aluminium. Speaking about his research and the urgency of adopting climatic architecture, Rahm underscores, “The idea of climatic architecture is to change the language and the tools of the discipline.”

Apart from the more theoretical basis of Rahm’s practice, the studio has been involved in proposals for built works, some of which are currently ongoing. These are interventions that consider the "gradualness of microclimatic conditions" or minutely manipulate space based on thermal considerations. For instance, the studio worked on the design of the Agora de Radio France, at the Maison de la Radio in Paris, transforming a large open landscape into a public space. Studying the site’s warmest and coldest regions by mapping places heated by the direct rays of the sun through computer simulations, the design was based on a variation of physical and social ambiences. Similarly, the studio’s most recent project in Taiwan, Jade Eco Park, was conceived by producing three maps showing heat, humidity and pollution conditions on the site, concluding with a microclimate map which identified cool, dry and clean air areas. Designed in collaboration with Mosbach Paysagistes and Ricky Liu & Associates, these maps helped the team divide different activities within the park. The landscape design accounts not only for activities and a range of functions, but actively considers comfort as shaping its manifestation. If comfort has so far not been a subject of architectural imagination, Rahm’s design philosophy centres this very negligence through his championing of the advantages of passive measures.

The last few years have seen a drastic shift in conversations around climate action. Calls for decarbonisation and mitigation of greenhouse gas emissions must actively consider what it means to stay with the discomfort of doing away with mechanical systems of heat regulation. We can no longer ignore the complicity of architecture in the slow degradation of our planet. In what forms can architecture address sustainability – the kind demands we build while reducing carbon emissions? By calling for an architecture of adaptation, the exhibition and by extension Rahm’s practice, hopes to make clear that it is within this uncomfortable space that we must operate.