It had the comforting scent of old times. Hearing the eminent Jean Nouvel expound on the need to “complete the skyline of La Défense” as our world collapses gave the feeling of being in a benevolent cocoon. A bit like hearing Franck Dubosc, snuggled up in your sofa under the warmth of a blanket, ask “So we’re not expecting Patrick?” ». The inauguration press conference, Thursday evening, of the Hekla tower in the Ile-de-France business district indeed seemed out of time.
Not once did Jean Nouvel, who designed the 220 m high (49 floors) office tower, mention climate change in his preliminary speech. He remained with architectural considerations, certainly deep and interesting, but completely out of step with the climatic question which today agitates architectural circles. Small excerpt:
The important thing is to give the building an identity, a character. […] There are too many cloned buildings in the world, you have to try to go down a path of identification. I wanted this building to be in the realm of a question, and the question is what makes the work of art. This tower is there to create a somewhere.
It was finally Xavier Musseau, the president of Hines France who, with AG Real Estate, were in a way the real estate developers of the tower, who brought the audience back to the sad reality. “We took into account the question of the sobriety of the materials we use,” he says. For example, we used recycled polypropylene for the concrete, which reduced the carbon footprint by 25%. »
A turn of the screw on the carbon footprint
The discrepancy seemed all the greater as the public establishment (EP) of Paris La Défense organized the day before its first general assembly of the transformation of the towers around three round tables, one of which was entitled “Rethinking the towers to go towards a post-carbon world”. Thus during this one the architect Raphaël Ménard launched that, faced with the climatic challenge, and because of the carbon cost of their construction and their operation, “we will undoubtedly have to give up new constructions of high buildings”. One day before the inauguration of a 76,000 m² office tower. “It’s the world before, adds his colleague Vera Matovic, head of agency B. We have an obligation not to build anymore. »
Philippe Chiambaretta, who heads the PCA-Stream agency behind the future Link tower, whose delivery is scheduled for 2025, wanted to be more measured in an interview he gave us recently:
For the carbon footprint of a building, you have to look at its life cycle, not just the act of building. We must not simply look at the energy and the carbon cost of the construction, which will certainly involve concrete, steel, glass and that, no doubt, is carbon. It is also necessary to take into account the movements of the occupants, the energy to heat and cool this tower. And the question of the ecological aberration of a tower no longer appears so simple. Is making five buildings, even in wooden construction, scattered around Paris where all the people will go by car for forty years is so advantageous in terms of the carbon footprint, compared to a tower which is placed on a transport node in common where no one comes by car?
He adds that the tower can solve the issue of urban sprawl. “With the population increasing, we make the city on the city and we densify, there is no alternative to that, he judges. It doesn’t shock me that there are places in the city where you can have a high density with towers. “Urban sprawl is more problematic than verticality,” said Xavier Musseau. The latter claims to “believe in verticality” but says he does not know if office towers will continue to be built.
A break between two rounds
It must be said that the latter are also faced with a change in working habits, in particular the development of teleworking and flex-office, which are quite significant in the tertiary sector, the main occupant of offices. Combined with the need to reduce its environmental footprint, this does not inspire optimism for office towers. “We will probably have to take a break in the construction of new offices until the market stabilizes and absorbs the new surfaces”, admits Pierre-Yves Guice, CEO of Paris La Défense.
And to the question of where was the marketing of the Hekla tower, the vague and unquantified answer of the president of Hines France did not reassure even if he certified “not to be worried”. “There is always a demand for offices, tempers Pierre-Yves Guice. In 2022, it is even significantly higher than the ten-year average. Now that Hekla is finished, it will be easier even if it remains a challenge to market more than 70,000 m² of office space. But if occupants are scarce, this could put off investors from committing to future tower projects.
Monoactivity will have to pass its turn
The salvation of the towers could pass in their adaptation to the world of tomorrow. Undoubtedly forgotten “the very slender cigarette towers”, denounced by Raphaël Ménard as “the private jets of architects”. For Vera Matovic, it will also be necessary to put an end to “intelligent buildings which are only stupid buildings”: “It is often unsuitable, quickly obsolete and you can very well lower a blind on your own. The towers of the future will therefore be different and much more sober. By the materials chosen, for example. Xavier Musseau thus estimated that the wood will take an increasingly important part even if it can hardly go in verticality.
Their use will also be different. The era of the monoactivity office tower is undoubtedly behind us. “Tomorrow, we will move towards more diversity of uses, but also of populations”, predicts Xavier Musseau. Moreover, as a foretaste of the future, the Hekla tower neighbors a student residence. Raphaël Ménard promotes the concept of a “tower as a metropolitan shelf”, which could combine housing, offices and shops.
And ultimately, the tower of tomorrow may simply be that of the past, but brought up to date. “At La Défense, there are approximately one million m² of offices to renovate, i.e. a quarter of the existing stock,” explains Pierre-Yves Guice. “We have to seize the existing, enjoins Vera Matovic, who has renovated a former site of the Ministry of the Interior to make it the premises of the group The echoes–The Parisian, in the 15th arrondissement. We must reclaim the housing stock. 90% of the city of tomorrow is already here. »