Our environmental commitments

The Centre des monuments nationaux is actively committed to environmental transition. This commitment, which is at the heart of the CMN 2030 strategic project, aims to reduce the environmental footprint of its activities while promoting the contribution of heritage in the face of environmental crises.

Since February 2024, the CMN has had a full-time CSR (Corporate Social Responsibility) Manager, thus complementing the expertise present within the conservation teams (experts in gardens and large estates, hydraulic expert).

Between January and June 2024, a wide-ranging consultation of staff and external stakeholders enabled the CMN 2030 strategic project to be co-constructed. The results of the consultation on ecology at the CMN, one of the six themes on which staff and stakeholders were questioned, made it possible to define a shared objective: to make heritage a major lever in the environmental transition.

The place of ecology in the CMN 2030 project confirms the impetus given by the "green CMN" plan initiated in 2013 ("zero phyto", eco-pasturing, ONF partnerships, LPO refuges, etc.) and the CMN's previous strategic plan (2017-2022), which enabled the CMN to step up several CSR steering mechanisms (sustainable purchasing policy, energy sobriety plan, employer mobility plan, etc.).

The new CSR roadmap on ecology, validated by the CMN Board of Directors in December 2024, consolidates these projects and initiates new ones, structured in seven areas: carbon footprint, circular economy, biodiversity & water, adaptation, eco-responsible purchasing, eco-responsible digital and awareness/training.

In 2023, CMN calculated the greenhouse gas emissions of all its activities. This overall carbon footprint (BEGES) was supplemented by a specific calculation for four monuments. The consolidated results have been integrated into a platform for managing the carbon footprint and the action plan for monitoring the reduction of greenhouse gas emissions under the SNBC (National Low Carbon Strategy). The CMN is also participating in the development of a carbon benchmark, in collaboration with the OPPIC, the ACMH and Carbone 4, in order to provide the heritage sector with the tools it needs to reduce its carbon footprint.

One of the challenges of CMN 2030 is to systematise our efforts to reduce greenhouse gas emissions from conservation activities, while taking into account the specific characteristics of heritage and rediscovering traditional conservation methods that can inspire more sober conservation solutions. This has led to the launch of the "Ecology of conservation" project. The first pillar of the CMN's strategy for sustainable heritage management is the development of a new intervention policy that gives priority to maintenance and repair, while promoting conservation restoration. Conservation ecology also involves preventing and adapting to environmental crises to ensure that our heritage is passed on to future generations. Finally, the ecology of conservation means not only reducing the impact of conservation activities, but also making the most of the contribution made by heritage to combating environmental crises.

The implementation of the sobriety plan in 2022 has made it possible to gradually replace heating and air conditioning systems with sustainable alternatives, such as heat pumps, Canadian wells or less polluting boilers. CMN is also taking action to control its energy consumption by measuring and automating data via the Deepki platform. Energy audits carried out on sites such as the Villa Savoye and the Château d'Angers complement this automated monitoring and identify solutions tailored to the specific characteristics of each monument. Where possible, thermal insulation work is undertaken, as at the Hôtel de la Marine and Mont-Dauphin. The switch to LED lighting and the signing of the Ecowatt charter are further steps in this drive to reduce energy consumption.

The CMN facilitates the use of soft mobility by forging partnerships with transport companies such as the SNCF, Eurostar and the RATP, and promotes accessibility to monuments using low-carbon modes of transport. Initiatives such as the inclusion of the Château de Carrouges in Normandie Tourisme's "low-carbon fares" scheme, the "Accueil vélo" label awarded to 12 monuments and the installation of bicycle parking facilities at 28 sites encourage more responsible travel. An experiment with the StationE recharging station has also been carried out at Châteaudun.

For its employees, the CMN has been rolling out an employer mobility plan since 2022, with 146 employees benefiting from the sustainable mobility package in 2023 and 603 employees benefiting from a 75% reimbursement of their transport tickets. The CMN's vehicle fleet is being transformed, with half of the new vehicles acquired now electric. Car-sharing is encouraged at several sites, such as the Saorge monastery and the Château d'Azay-le-Rideau, and charging points and sockets for electric vehicles have been installed, notably at the Cité internationale de la langue française and the Hôtel de Lunas.

To reduce waste and encourage re-use, CMN includes recycling and waste treatment clauses in its calls for tenders. The bookshop-boutiques use second-hand furniture and donate unsold items to associations such as Secours populaire. Exhibitions are also part of an eco-design approach, like "Oser la liberté" or "Nouvelles reines" in Saint-Denis, thanks in particular to exchanges between the monuments in the network (sharing showcases and scenographic elements). The experiment carried out as part of the Heritage Incubator with Re'up has also identified the need for monuments to have tools for identifying the resources present on their sites, so that they can then find the best outlets for the resources stored.

Selective sorting has been introduced at 53 monuments. Some sites, such as the Villa Cavrois and the Abbey of Mont-Saint-Michel, have committed to a zero waste approach. Composting is gradually being rolled out, as at Fort Saint-André and the Domaine National de Saint-Cloud, where a dedicated area has been created to process green waste. The installation of drinking water fountains for the public completes these initiatives.

Since 2011, CMN teams have been favouring alternative and ecological solutions to achieve the "zero phyto" objective (hand weeding, release of lacewings, etc.). Practices such as eco-pasturing also help to promote soil biodiversity. Scattering wood chips is another technique used to regenerate the soil (and also optimise water use). Since 2008, the CMN has applied the Natura 2000 charter to 15 monuments located in ecologically sensitive areas, such as the Château d'If. Half of the CMN's green spaces have been labelled or protected. Nine gardens have been awarded the "Jardins Remarquables" label and the network now includes 18 LPO refuges. New inventories and naturalist studies are planned to gain a better understanding of the biodiversity present in the monuments in the network.

Replanting projects such as the creation of a flower meadow at the Château de Maison and the creation of wetlands such as the re-watering of George Sand's island also illustrate the efforts being made to create biodiversity refuges.

This approach to protecting biodiversity also applies to the plant and agricultural production of certain sites, such as the Château de Voltaire in Ferney, where the garden is cultivated using permaculture methods by the association "Les Jardins de Voltaire", or Carnac, where herbal teas are produced from plants picked from the alignments.

In response to the consequences of climate change, the CMN is adapting its infrastructures and practices. Adapted opening hours have been introduced and islands of coolness have been created, such as at Montmajour Abbey and in the courtyard of the Governor's dwelling in the towers and ramparts of Aigues-Mortes. The choice of vegetation around buildings takes into account the risk of fire, and emergency measures have also been put in place on certain sites.

The CMN also contributes to research projects on adapting heritage to environmental crises. Since September 2024, for example, the fortress of Mont-Dauphin has been taking part in the Erasmus + project "A Resilient Fortress", in partnership with the fortresses of Suomenlinna (Finland), Naarden (Netherlands) and Antibes (France).

CMN favours the re-use of terminals: an audit of unused IT equipment is carried out by Recyclea, which then offers re-use channels. Hosting is also part of an eco-responsible approach, with the choice of Inetum, CMN's EcoVadis, ISO 14001 and ISO 50 00 certified host, to migrate to a more efficient data centre (PUE <1.2) in 2023.

The Strategy, Foresight and Digital mission has obtained "Responsible Digital" certification after completing the INR's Responsible Digital MOOC in 2022 and participating in the Responsible Digital AuguresLab in 2025. As part of the "CMN Numérique" programme, environmental impact models have been produced by the start-up ZenT to assess the carbon footprint of VR and remote visits.

The CMN has also developed a 'Responsible Digital' action plan to meet the requirements of the responsible digital label.

The CMN proposes participative actions such as the "Clean Up Nature" initiative at the Domaine national de Saint-Cloud and events linked to the site's flora and fauna. The Montmaurin and Salses fortresses, for example, are taking part in the International Bat Night. The fortress of Mont-Dauphin and the archaeological site of Glanum offer tours and workshops on the biodiversity of the site. Visitors to Rambouillet can also discover the estate on boat trips and cultural bike rides.

Explanatory panels also provide a better understanding of the initiatives implemented on the sites (eco-pasturing, late mowing, etc.).

A number of temporary exhibitions hosted by the monuments have featured artistic projects linked to environmental issues, such as Suzanne Husky's exhibition "Histoire des alliances avec le peuple castor" (History of alliances with the beaver people) presented from June to November 2024 at the Château de Châteaudun.

The CMN 2030 consultation revealed strong expectations among CMN staff in terms of eco-responsibility. An "eco-challenge" was therefore launched in January 2025: 100 workshops enabled 800 employees to identify the levers for taking action and to define the priority actions for the network's departments and monuments.

Training courses on biodiversity issues and support for the environmental transition have also been included in the Human Resources Department's 2025 training catalogue.

By integrating the challenges of ecological transition into all its activities, the CMN is making heritage a driving force behind ecological transition, demonstrating that preserving our past can help build a sustainable future.