One of todays great challenges is reconciling the sustainability of our cities in the face of climate change with the preservation of monuments and community access. In this regard, Belgian architect Bas Smets is among those redefining what is possible An internationally renowned landscape architect, Bas Smets views the landscape as an extension of nature. For Smets, plants are not mere decorative elements but active agents in creating a self-sustaining microclimate. Over the years, this vision has manifested in innovative projects that combine scientific research, design, and technology. From transforming the area around Notre-Dame to designing the Belgian Pavilion at the 2025 Venice Architecture Biennale, his work is based on a deep philosophical reflection on the relationship between nature and urban space.
In your architectural practice, you emphasize a method over a style. What does your method entail?
My method, “biospheric urbanism,” involves seeing the city as a “second nature,” where buildings modify prevailing winds and alter solar exposure. Streets and squares change water runoff, affecting permeability. With my students at the Harvard Graduate School of Design, we study a city each year to understand how it can become resilient to climate change.
In your practice, urban space is an extension of nature. How important is it to rethink our mental frameworks to create more sustainable environments?
I believe we need to move away from the opposition between culture and nature and from viewing the environment as something merely around us; we are part of it. Darwin noted that plants shape the environment more than the environment shapes plants. Plants indeed produce the environment we live in, so as architects, our focus should be on the cohabitation between plant and animal life.
You have been teaching at Harvard for two years, analyzing cities to improve resilience to climate change. Can you provide examples?
So far, we’ve studied New York, Paris, and Athens, imagining global warming scenarios at +2°C, +3°C, +4°C, and +5°C. As climate change becomes more drastic, solutions must become more radical. Paris, for example, has seriously addressed climate change over the past decade by mass planting trees and reevaluating soil permeability, a model many cities may soon follow.
You emphasize the importance of soil, especially in your project redesigning the area around Notre-Dame. Can you elaborate?
Soil enables plant life, but in our cities, we’ve created an impermeable layer preventing rainwater from infiltrating the ground. This results in lowered water levels, making even ancient trees unable to access water, leading to droughts and floods. To address this, in various projects, we’ve created artificial aquifers under sidewalks to plant trees that return water to the atmosphere, cooling the air. At Notre-Dame, alongside NGA and GRAU architects, we redesigned the public space around the cathedral and transformed the unused underground parking into a visitor center. Here, we collect rainwater for irrigation and cooling the environment through evaporation.
How did you balance environmental sustainability, community, and historical heritage in the Notre-Dame project?
Working with monuments is crucial because they have succeeded in the grand laboratory of the city. Our goal was to create a climate space around Notre-Dame, studying the Seine’s wind, trees’ evapotranspiration, and sunlight reflection. We needed to respect history while projecting into the future, balancing reverence for the past with an understanding of its evolution over the next 10, 20, or even 100 years.
How did your collaboration with Stefano Mancuso for the Belgian pavilion at the Venice Architecture Biennale come about?
For Venice, I asked Stefano to integrate plants into a controlled microclimate. A building is already a microclimate: it blocks the sun and wind, simulating the understory of a subtropical forest, except it doesn’t rain. We placed sensors in the plants, allowing lighting, irrigation, and ventilation to be dictated by the trees themselves, creating a microclimate within the pavilion. This is no longer traditional air conditioning but rather a “natural intelligence” that regulates internal conditions.
In the past, you’ve expressed skepticism about the climate future, yet your work reflects a hopeful approach. Can you explain this?
We live in an interesting historical moment. On one hand, artificial intelligence presents both promise and threat; on the other, we have NI, “natural intelligence,” which we are beginning to understand much better. Compared to ten or twenty years ago, there has been a radical awareness of climate change. Faced with imminent danger, there are two options: remain paralyzed and inactive or choose to act by every possible means, even without assurance of success. For me, action is a moral obligation.
