In search of tradeoff for a sustainable ALAN – LUNNE

The project integrates different aspects (societal, environmental, technical) of ALAN reduction. Methods and tools from different academic fields (human and animal vision, social and environmental psychology, applied mathematics) are used. In WP2 and WP3, we will mobilize concepts from social psychology, in particular acceptability and the theory of the network actor. In WP3, concepts from psychophysics and environmental psychology will be used to address urban nocturnal ambiance. We will also use data analysis techniques based on observations of user trajectories. WP4 will use concepts from animal photometry, and different modeling techniques, particularly in geomatics. The notions shared by all participants in this project are those relating to photometry and lighting.

The project proposes an approach at different spatial scales. The consequences of ALAN on ecosystems are indeed observable at the scale of the luminaire (for example the trapping of insects), of the streets (light barriers, dark reserves), and of the city (with the luminous halo reflected by the atmosphere beyond the illuminated areas). This makes the use of maps relevant: they make it possible to describe the effects of ALAN to spatially plan lighting at the territorial level and reduce the pressure exerted by ALAN on ecosystems. They are also tools for consultation. with the populations, usable by elected officials and technical services.

The strong point of the proposed indicators, compared to those used by local authorities or taken from the scientific literature, is their greater adequacy to the objectives of sustainable development. Some of the indicators proposed in this project are original, using animal photometric data to assess the impact of sources on insects, and transposing the viewshed and isovist concepts from geomatics to identify darkness areas, which can then be characterized (size, connectivity). Concerning the evaluation of the quality of urban lighting for pedestrians, the spatialized approach to city lighting (dark networks, levels and/or light spectra) leads us to go beyond the characterization of light environments for a static pedestrian and to focus on the moods and behaviors induced by the transitions between differently lit areas. The association of perceptual, behavioral and photometric data is also an original approach to bring out measurable indicators of the service provided by lighting from a functional point of view, and to identify the acceptable limits with regard to the various criteria.

The main expected results of this project are:

* An inventory of lighting strategies aimed at reducing the impact on the environment;
* The development of a methodology for consultation and integration of environmental criteria in the public decision-making process concerning lighting;
* A better understanding of the impact of these strategies on the safety, comfort and mobility of pedestrians;
* Identification of obstacles and levers to the acceptability of urban lighting sobriety policies;
* Indicators of the quality of the luminaires with regard to the associated nuisances (detectability, attractiveness, glare);
* Indicators of the impact of lighting policies on the light halo and urban dark areas (areas without visible light points).

Our research should make it possible to develop standards and regulations towards controlled light sobriety, which can be done at the international level through participation in existing (or future) Technical Committees of the International Commission on Illumination (CIE), in which some members of the consortium are already participating (e.g. TC4.61 Artificial Lighting and its Impact on the Natural Environment).

In the context of smart lighting, the proposed methodology may enable local authorities to better control lighting (particularly via performance contracts) relying on city monitoring, whether to estimate the indicators defined in the project or by dynamic lighting control. In terms of acceptability by the populations and by the technical services, the proposed consultation methodology could inspire new approaches, either directly or through guides intended for local authorities and proposed by national organizations (ADEME, CEREMA); CEREMA being directly involved in several aspects of the project, the creation and dissemination of the national technical standards on these subjects will be facilitated (drafting of guides, animation of technical days, training).

We hope that the LUNNE project may help local authorities in the management of their lighting, taking better account of the objectives of sustainable development in the use of technological innovations. These developments may relate to lamp technology, centralized lighting devices, smart lighting or lighting planning. A possible application would be the identification of nocturnal corridors that favor the migrations and movements of fauna.

The involvement of national lighting actors, such as the Association Française de l'Eclairage and the Cluster Lumière will allow the dissemination of the project's results to public and industrial operational stakeholders. . The promotion of scientific and technical culture (e.g. media, science festival) will be carried out in partnership with the communication department of our establishments. On another level, this national project could be a springboard for considering a European project on the theme of light sobriety.

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The master planning of sustainable urban nightscapes requires a parsimonious use of artificial light at night (ALAN) to meet societal needs for safety, mobility, economic and social life, while limiting energy consumption, and negative impacts for humans, for the climate and for biodiversity. But in order to promote light sobriety, lighting modifications must be acceptable to the public, and technically feasible.
As the suppression of ALAN is not always an acceptable option, it is necessary to understand the constraints and the needs of the different actors in order to promote sustainable urban lighting. The development of Smart Cities and the possibilities brought by the LED technology opens up new strategies to reduce ALAN while controlling its impact on ecosystems and on the quality of life.
The LUNNE project addresses several scientific challenges associated with the reduction of ALAN: 1) A more appropriate quantification of the impact of ALAN reduction strategies on ecosystems, through the development of new indicators at different spatial scales. 2) A better knowledge and quantification of the impact of these strategies on people (mobility, safety, nightlife). 3) A better understanding of the obstacles and levers to the acceptability of these urban lighting policies. All three dimensions will merge into multi-factor indices and specific methodologies, providing urban communities with decision-making tools to consider the specificities of their territory when they adapt their lighting.
The impact of lighting modifications will be studied by combining the collection of behavioural data in urban observatories, the collection of subjective and social data through surveys, the collection of photometric data through measurements, and the implementation of computational models.