Lyon (Rhone). On the slopes of Croix-Rousse, in the Haussmannian buildings of the Presqu’île or in Renaissance Old Lyon, summers become a little more trying each year for the inhabitants of downtown Lyon. These three districts which make up the historic site of Lyon, inscribed on the world heritage list of the United Nations Educational, Scientific and Cultural Organization (UNESCO) in 1998, must urgently adapt to future climates which will soon resemble those of the South of Spain. On the occasion of the revision of the “Unesco” management plan for the property, carried out by the City and the State and unveiled in June, Lyon is taking a course to bring its two-thousand-year-old heritage into a warmer era. .
Because if we usually talk about “summer comfort” to discuss the insulation performance of buildings in the face of high heat, Sylvain Godinot, deputy mayor (EELV) in charge of heritage, talks to him about a “health issue” : “ When we have nights over 25 degrees, we are no longer dealing with a comfort issue, but with a health problem. The management plan must make it possible to find solutions, with heritage professionals and energy specialists. » The liveability of the city center thus becomes one of the common threads of the 2024-2030 Management Plan.
On the banks of the Saône and the Rhône, climate warming is already generating behaviors that put the protection of heritage under pressure: “Our town planning department has noticed an explosion in demand for the installation of air conditioners, reports the heritage assistant. Even if they are installed on roofs, they are visible from the hills. In the interior courtyards, often trabouled, there is also a heritage value. And no one has the means to control the regulations: for every ten requests to the planning department refused, there are nine illegal installations…”
To respond to this challenge, the City and State services are considering urban planning based on several parameters: the reduction of automobile traffic, already initiated by the environmentalist town hall, or the revegetation of the heart of Lyon, which requires the revision of some heritage preconceptions about urban minerality. Major projects undertaken by the metropolis of Lyon, such as the “Presqu’île à vivre” project aimed at pedestrianizing and greening a large portion of the district, are already moving in this direction.
The studies carried out as part of this new management plan also encourage the enhancement of the intrinsic qualities of heritage buildings, in terms of energy inertia, exposure or location near waterways. The famous Lyon traboules are also an asset, promoting air circulation in the heart of the islands… when they are not invaded by air conditioners. Saturated with heat pumps and air conditioning, “the spaces no longer play their role of regulating air currents, their permeability capacities are reduced”, can we read in this management plan. These passive solutions alone will not be enough to provide a habitable city with the temperatures of 2040: a reflection has thus begun around an urban cooling network, which already exists on the Part-Dieu side. Heavy and complex work which would nevertheless offer a lasting solution.
An extension of the remarkable heritage site
The establishment of a new remarkable heritage site (SPR) should also provide a framework for the intersecting objectives of heritage preservation and habitability of the urban center. In joint preparatory work with the Metropolis and the Regional Directorate of Cultural Affairs (DRAC), the city retained the scenario of an extension of the current SPR, which only covers the Renaissance district of Old Lyon, to encompass a good part of the Peninsula. “We are going to finish the preliminary studies on this mandate, indicates Sylvain Godinot, for entry into force by 2032. In the report submitted to UNESCO, we see that the heritage has been well preserved thanks to the first management plan. The challenge is not so much to provide better protection, but to have clearer rules, and to simplify the task of architects of French buildings and town planners. »
On the heritage level, the management plan proposes two actions to strengthen the consideration of two constituent periods of the Unesco property: the ancient archaeological heritage, with a large program of development and study of the sites, and the 19th-20th century buildings. , through a census study and a reflection on its rehabilitation. “In this promotion, we want to address above all the inhabitants of the territory”specifies the deputy mayor. The “Unesco” management plan, like the future SPR, responds well to a strong political objective of the city, the maintenance of inhabitants and activities within the city center. The same, ultimately, which led to the mobilization against the planned destruction of Old Lyon in the 1960s, and to the creation of the very first French protected sector.