Arguing for “intelligent rehabilitation” of existing buildings

Our homes and old towns will be uninhabitable by 2050, warn the architects Sébastien Clément and Emmanuel Mille, and the philosopher Thierry Paquot, who argue for an “intelligent rehabilitation” of existing buildings in an article on Le Monde website.


For a heritage policy consistent with the climate emergency

June 2020 was the warmest month on record in the world. The previous record was only in 2019! Siberia is facing an unprecedented heat wave, last winter set records for mildness, and this spring was the second warmest on record.

The Covid-19 health crisis underscores the issue. After several months of confinement in apartments, people crave green spaces. The environment, current and future, has taken an unprecedented place in debates for municipal elections. And the results, especially in the big cities, speak volumes about voters’ expectation of change.

Cosmetic and opportunistic ecology

Yet there is a risk that programmes with eccentric projects that may actually be bad for the ecology, will be adopted, particularly in Paris: creation of forests on flagstones, planted bridges, green facades, ecological towers. This kind of ecology is cosmetic and opportunistic and does not in any way address the real challenges. In the past, cities always accounted for the climate, using locally available materials and the expertise of craftsmen. Technical progress and cheap fossil fuels in the era of high production have set a standard comfort for all. This progress is now coming up against global warming and the depletion of resources. Our homes and old towns, which were not designed for scorching temperatures, will be uninhabitable by 2050!

In order to make cities livable there must be changes to both buildings and public spaces. In the context of resource depletion, the disastrous carbon footprint of conventional new construction, and the risk of accelerating urban sprawl, we must strongly encourage the renovation of existing buildings.

The absolute need to reduce the carbon footprint rules out high-tech, expensive, unsustainable and ecologically questionable solutions 

Massive energy renovation is supposed to be one of the pillars of the post-crisis economic recovery, but we should be wary of hasty solutions. Insulating the outside façade of historic buildings often damages the aesthetics and the vapour barrier can cause conservation problems for the structure of the building: most old materials need to breathe to last. Similarly, bio-based insulators are preferable to synthetic materials, which are certainly more economical but are very questionable from an environmental point of view.

The absolute need to reduce our carbon footprint rules out high-tech, costly, unsustainable and ecologically questionable solutions. For solutions that are consistent with today’s climate context, Mediterranean countries offer us a plethora of layman’s approaches that are well adapted to the logic of building construction, such as use of inert materials, cross-ventilation, capturing cool air from cellars, etc.

Early photographs of Haussmannian Paris show pedestrians coming and going through squares, boulevards, and streets – not channeled onto cramped sidewalks which have become more dangerous as they are also used by bikes, scooters and motorcycles. Streets have long since been turned over to the automobile, often immobile …

It is crucial to create shade, for example by creating urban umbrellas and planting tall trees. With rising temperatures, it would be absurd to restore stone surfaces on squares and public spaces such as the Place du Panthéon or the Bastille without also envisaging shade and hygrothermal comfort that can be provided by well-chosen vegetation and permeable soils. Similarly, it will no longer make sense to choose the kind of dark, heat-absorbing ground coverings that are sometimes used for cycling paths.

Ecological transformation will, in part, mean the restoration of heritage. Stone ground cover is partly responsible for the saturation of the sewers. With recurrent episodes of droughts and floods, or less frequent but more violent rain, soil infiltration is no longer a gadget in “green neighborhoods” but a necessity for water regulation and hygrothermal comfort.

Reducing the priority on the car would give greater priority to pedestrians – especially children. And it would also allow for permeable ground covering as well as more open planted spaces that are a source of fresh air.

Heritage, a precious beacon 

Heritage is never better preserved than when it is occupied, heated and ventilated, maintained, alive! Heritage loses all its meaning if its use is limited to tourism. Old cities must be used for housing, including for people with modest incomes.

Heritage policy has always been focused mainly on aesthetic and normative issues, but now policy could open up to how heritage is used in ways that are consistent with the new climate and health context. It is better to protect an ordinary building, and to adapt it to the new context. Practitioners in the sector, and especially the architects of Bâtiments de France, must be at the forefront of implementing these transformations. In this uncertain world, heritage constitutes a precious beacon appreciated by every citizen. Heritage is at one with ecology – its historical face which tomorrow will testify to yesterday. A society that loses its memory has no future.


About the authors

Sébastien Clément is a heritage architect and professor at the IUT of Evry; Emmanuel Mille is a heritage architect and doctoral student at the CRAterre laboratory – National School of Architecture in Grenoble; Thierry Paquot is a philosopher, professor emeritus at the Paris Institute of Urbanism, author of “Urban Disasters, cities also die” (La Découverte, 2019).Sébastien Clément (Heritage Architect), Emmanuel Mille (Heritage Architect) and Thierry Paquot (Philosopher)

External link. [original in French]

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