# Sociological approach to the territorialization of night-time atmospheres

Houel Nicolas, Potard Saïg

► To cite this version:

Houel Nicolas, Potard Saïg. Sociological approach to the territorialization of night-time atmospheres. 8th International Light Symposium: Re-thinking Lighting Design in a Sustainable Future (Light Symposium 2022), Sep 2022, Copenhague, Denmark. pp.361-372, 10.1088/1755-1315/1099/1/012036. hal-05161157

HAL Id: hal-05161157

https://hal.science/hal-05161157v1

Submitted on 14 Jul 2025

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
PAPER • OPEN ACCESS

Sociological approach to the territorialization of
night-time atmospheres

To cite this article: Houel Nicolas and Potard Saïg 2022 *IOP Conf. Ser.: Earth Environ. Sci. 1099* 012036

View the [article online](#) for updates and enhancements.

You may also like

- *Nocturnal sap flow of Hedysarum scoparium and its response to meteorological factors in semiarid Northwest China*
Jifeng Deng and Hangyong Zhu

- Investigation of low-level-jets over rural and urban areas using two sodars
M A Kallistratova

- Feasible assessment of recovery and cardiovascular health: accuracy of nocturnal HR and HRV assessed via ring PPG in comparison to medical grade ECG
Hannu Kinnunen, Aleksi Rantanen, Tuomas Kenttä et al.

UNITED THROUGH SCIENCE & TECHNOLOGY

<figure><img src="image_2.png" /></figure>

The Electrochemical Society
Advancing solid state & electrochemical science & technology

248th
ECS Meeting
Chicago, IL
October 12-16, 2025
Hilton Chicago

<figure><img src="image_3.png" /></figure>

Science +
Technology +
YOU!

Register by
September 22
to save $$

REGISTER NOW
# Sociological approach to the territorialization of night-time atmospheres

Houel Nicolas (1), Potard Saïg (2)

(1) Associate Researcher at the AAU Laboratory - ENSA Nantes, France, founder of the company L'Observatoire de la nuit

(2) Head of Public Lighting, Light Signals and Telecommunications Networks Division of Brest Métropole, France

Nicolas.houel@gmail.com, saig.potard@brest-metropole.fr

**Abstract.** This article presents a case study conducted in the metropolis of Brest, France in 2022, designed to support public policy decision-making by integrating the knowledge and needs of citizens during the different stages of a night-time urban planning project, around the notion of synchronization of the city's rhythms. It presents three innovations: (1) Actors: coordination of public and private actors, common vocabulary, cartographic representations of assets, introduction of participatory approaches, activation of citizen knowledge in political expertise. (2) Sociology: participative modalities, objectification of citizens' knowledge, definition of their decision-making perimeter, (3) Public lighting policies: territorial and social strategy of light sobriety, regularization and empowerment of the network of actors. The conclusion of this article will focus on the limits, added values and development axes of nocturnal urban sociology as a support for decision-making in public lighting management and renovation strategies, and will open up the mobilization of the rhythms and temporalities to be mobilized in order to restore balanced nocturnal ambiences between lighting, which is essential, and darkness, which is vital.

## 1. Introduction

Since 2018, public lighting in France has been subject to a regulatory framework of mandatory application, underlining the urgency of a shift towards its sobriety[1]. Its determinants are the reduction of energy consumption and light pollution[2] and the preservation of natural night environments[3]. Guides, labels and actions now qualify darkness as a resource[4]. In parallel, sociological initiatives are opening up[5], presenting isolated participative approaches, often mobilized in a political framework seeking to verify a proposal for an atmosphere that is already underway.

In the follow-up of energy and environmental awareness, we propose to deepen the territorial role of the societal awareness of the relation to night-time ambiences. Today, the user migrates from a passive posture, developed in front of a safety artificial lighting[6], then advertising[7], towards a role of actor of the reduction of light pollution[8].

<figure><img src="image_4.png" /></figure>

Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.
However, the notions of citizen knowledge are rarely mobilized in the framework of operational lighting projects [9]. Only some scientific studies explore the fields of individual perception [10]. Finally, the notion of rhythms [11] plays a decisive role: rhythms of technological innovations, political mandates, regulatory changes, renovation of heritage and the daily life of regular or occasional night-time users. This is where our problem lies: Can the identification of ordinary and extraordinary rhythms and uses become a support for decision making in political and technical strategies for artificial lighting sobriety?

The main motivation of the project lies in the political decision support of the territorialization strategies of public lighting (regimes, forms, photometries, atmospheres). It is part of the operational approach of the Schéma Directeur d'Ambiances Nocturnes (SCAN), or Nocturnal Ambience Coherence Scheme (NACS) initiated by Brest Métropole. Its methodology works in three phases:

- Diagnosis of the lighting assets, help in determining the political, technical and social issues pursued by the community,

- Territorialization of the issues by opening them up to the expertise of experts [12] and users,

- Definition of a strategy for the creation and renovation of lighting assets determined in time and space and represented by an evolutive digital cartographic support.

We will present this case study by taking as a starting point the ambition of luminous sobriety which has become essential in view of the energy, environmental and societal breaking points encountered today in artificial lighting practices.

Through the study of these elements, we will observe the transformation of urban and rural nocturnal ambiences towards the concept of the black grid. The latter will be observed as a form of imposed restoration of darkness in inhabited areas, for the benefit of energy sobriety and respect of the environment. We will question the decisional, operational and innovation temporalities, which are nowadays decisive in the maintenance of the lighting practice framework. We will propose an adaptation towards a concept that could be unifying, that of the rhythm of the city and its uses.

## 2. Sobriety issues in Brest Métropole

The challenges of sobriety expected from street lighting are becoming prominent in France. Since 2018, they have been the subject of specific national regulations to reduce light pollution emissions<fnref n="1" />. In 2021, an annual public report<fnref n="2" /> was published highlighting the lack of an ambitious and long-term vision for the management of this heritage, whose obsolescence represents a significant source of energy consumption, which can definitely be improved. Faced with these observations, a growing number of authorities have embarked on the study of renovation strategies that are often unilateral (energy/environment) and prioritize the extinction of lights in more or less extensive areas of their territories and according to time slots that are most often determined without analysing local night-time activities.

These new practices, which are virtuous in terms of the objective of sobriety, are however out of step with the priority service of street lighting: to accompany individuals moving about in the public space at night. Determining these new street lighting practices involves considerable work, both in terms of cost and time. To undertake them without a detailed analysis of local night-time rhythms and uses, both daily and occasional, presents, from our point of view, the non-negligible risk of an evolution

<footnote n="1">¹ We refer to the ministerial order of December 27, 2018 on the prevention, reduction and limitation of light pollution. [URL] https://www.legifrance.gouv.fr/loda/id/JORFTEXT000037864346/ - last consultation on 06/08/2022.</footnote>

<footnote n="2">² We refer to the annual public report of the Cour des Comptes, published on 18 March 2021. [URL] https://www.ccomptes.fr/fr/documents/55052 - last consultation on 06/08/2022.</footnote>
of a public service - street lighting - which has been renovated but which is nevertheless out of sync
with its initial objective: to accompany uses.

Here, sobriety as a territorial strategy is understood with the help of the developers and users of the
places concerned. It is part of a system where considerations related to the preservation of energy
and the environment are balanced according to the expertise of both administrators and users,
according to a bottom-up logic where the expertise of uses comes to complete and enhance the
technical and political expertise. Our case study, located on the territory of Brest Metropole, France,
presents the first steps of this methodology.

## 2.1. Brest métropole

In 2022, the Brest metropolitan area will have more than 36,000 light points. These are spread over 8 municipalities and provide a public service to nearly 208,500 inhabitants, i.e. nearly one light point for every 6 inhabitants. Given this vast territory, the metropolis is pursuing a global approach to the operation of lighting and a homogeneous strategy for taking needs into account. Historically committed to an approach based on sobriety, Brest Metropole presents a technical management based on night-time cut-off and dimming of public lighting. This configuration, initially defined empirically by knowledge of the territory and its uses, is now evolving according to the observation of real traffic conditions and feedback from citizens, in order to get closer and closer to the reality of uses.

## 2.2. Actors and coordination

The metropolis is responsible for the creation, development, management and maintenance of public
space in the community and municipal domains and its facilities. Political governance is carried out by
the elected vice-presidents responsible for services to the population and territorial proximity.

The “street lighting” unit is part of the "Public Lighting, Illuminated Signals and Telecommunications Networks" Division, which is part of the "Roads, Networks and Infrastructures" Department of the "Public Space and Environment" division of Brest Metropole.

The “street lighting” department is made up of an engineer and two technicians, who develop the
community's strategy by proposing asset renovation programs and monitoring the operation of the
network in the best possible conditions. In order to maintain control over operations, the community has
chosen to delegate management by relying on two public contracts with purchase orders, one for new
work and another for maintenance.

## 2.3. The project for Nocturnal Ambience Coherence Scheme (NACS)

Brest Metropole has begun studies to develop a Nocturnal Ambience Coherence Scheme. This initiative is fully in line with action no. 56 of the Brest Metropole's territorial climate and energy plan: the pursuit and enhancement of the energy optimization of the public lighting network. The NACS continues to define local policies in terms of public lighting, which it develops in light of contemporary energy and environmental issues. It is interested in political, technical and technological innovations, which it territorializes by integrating a sociological approach conducted by action research protocols and the development of participatory survey methods dedicated to nighttime environments, in order to meet the objective of “lighting right”.

NACS proposes a 3-step methodology. The first step proposes a transversal approach to the various
departments involved in the development of public space in order to understand the needs and levers of
action of each. At the same time, it allows to measure the different levels of political and technical
complexity of public space planning, and to set up a shared vocabulary, around the issues of night time
ambience, between political decision makers and public engineers and planners. These exchanges take
the form of collaborative workshops, from which a general street lighting strategy oriented towards
sobriety emerges. We believe that this first strategy is out of sync with the habits of the territory's night-time users, who are not consulted during its development. Therefore, a second step called territorialization is proposed. This step aims at identifying and valorizing the daily and occasional night activities of the users in professional and recreational situations. Like step 1, it takes place in the form of workshops, this time with citizens, and allows the establishment of a shared vocabulary on a larger scale. The result is a so-called territorial strategy, where the night-time atmosphere is sober and adapted to the activities of the users.

However, this work is carried out without any experiential form of the imagined atmospheres. The NACS proposes a final stage of experimentation of the future ambiances. This last one can be done in real conditions or in a simulator, and aims at presenting the future spatialized environments to the decision makers, technicians and citizens. The experimentation finally allows to represent and to value the political and technical commitments towards a reasoned lighting (fig. 1).

<figure><img src="image_5.png" /><figcaption>Figure 1 - Diagram of the NACS methodology: synchronize the political and technical expertise of artificial lighting with the uses in order to produce adapted and evolving night atmospheres</figcaption></figure>

The objective of providing the right lighting for the city continues to be developed in the precise definition of the lighting service, taking into account all of the challenges facing public spaces, whether they are societal, urban, energetic, environmental, economic, tourist or even innovative. For Brest Metropole, designing the right public lighting involves a global approach to these issues, with a system of varying and evolving priorities depending on the spatial and temporal contexts, understood under the notion of rhythms.
### 3. From black frames to nocturnal rhythms

On a national scale, these dynamics of sobriety are today motivated by a dominant concept, although still awaiting a precise and shared definition, of the black frame. The environmental backlash to the luminous generosity of the second half of the 20th century, the nocturnal landscapes of the 2020s are seeing their ambiences determined by a quantity of artificial lighting measured as close as possible to the respect of the environment, participating in the emergence of these black frames, geographical interpretations locally superimposed on the green and blue frames, sometimes enhanced by atlases of biodiversity, exceptionally augmented by rhythmic and temporal emergences. These black frames, widely debated in academic and operational circles, are currently making their way towards the notions of dark frames, where lighting is moderated, and light frames, where lighting is preserved with regard to identified uses on the ground.

The grid approach is a first form of local response to the challenges of preserving biodiversity. Nevertheless, it still seems to be insufficiently supported by the necessary identification of the fauna and flora species of the places concerned, nor of their rhythms (permanent or seasonal presence). Thus, the grid approach presents geographical strategies that must now be associated with rhythmic strategies for flora, fauna and humans.

Through this territorial approach of mutualizing space and time indicators, one of the major evolutions of the future of urban nights is presented, that of a correspondence to the ordinary and extraordinary uses of nocturnal space-time. The city of Brest, with its years of participative experience, is committed to experimenting with the development of a strategy for harmonized nighttime atmospheres for all users in its territory.

### 4. Territorialization: enhancing the transversality of nighttime urbanism

The harmonization of a public service to its users is understood under the notion of territorialization, in this case of night-time environments, affordable at least under two aspects:

1. In political science, territorialization consists in identifying and valorizing territorial specificities, through an approach to public policies that encourages interdepartmental cooperation.

2. In the academic community, the geographer Claude Raffestin explores "nocturnal territorialities", understood as our daily, ordinary practices and uses of nocturnal spaces.

In France, where the development of public space is organized in silos (green spaces, roads, traffic lights, public tranquility, urban quality, new mobility, public lighting, etc.), the question of night-time environments is regularly treated in a secondary, primarily technical manner, except in specific cases of large-scale urban development. Skills, knowledge, budgets and meeting time are reduced to a strict minimum, to the benefit of a reflection on daytime developments and associated atmospheres.

Our study explores a methodology for cross-cutting issues related to street lighting. We propose to approach aspects 1 (political science) and 2 (academic) from a similar angle: meeting and sharing knowledge with planners and decision-makers (aspect 1) and then with panels of professional or private night-time users (aspect 2). This approach will allow us to present to decision-makers and users the different levels of complexity now encountered in the management of street lighting, and in parallel to grasp, from their expertise, the levels of complexity they encounter in the administration of their own sectors of:

- Expertise (decision-makers/planners),

- Uses (users).
This step, entitled common vocabulary, will allow us to set all the participants at an equal level of knowledge (vocabulary, issues, needs, expectations). It is carried out in the form of interviews and is considered to be the preliminary stage in the development of the NACS of the metropolis.

**5. Brest Metropole: the levels of collaboration in the service of the territory's nocturnal resilience**

In Brest, the Nocturnal Ambience Coherence Scheme is an innovative, qualitative and sensitive approach to nocturnal spaces and temporalities. Mobilized in the design of lighting environments, it reveals their complexity and accompanies the management of change through a collaborative modality deployed in 3 stages: A preliminary stage of transversal diagnosis; a first phase of territorialization, called general strategy; a second phase of territorialization, called territorial strategy.

**5.1. Transversal diagnosis**

The transversal diagnosis maps the lighting data of Brest Metropole as well as all the physical indicators of the public space: road network, centrality poles, natural spaces, school sectors, or tourist points of interest. It allows the first indications of complexity to emerge between the historical roles attributed to artificial lighting and contemporary aspirations for environmental respect, energy and social resilience.

**5.2. General strategy**

A first phase of territorialization, known as the general strategy, initiated by interdepartmental cooperation. It aims at a broad definition of the needs and expectations of each department of the public space department in terms of night-time ambience. This first step encourages the de-siloing and allows to reveal the richness of the current stakes fed by reasoned practices of artificial lighting. It opens the way to the definition of a macro-scale strategy, oriented towards lighting sobriety and transcribed via an interactive digital interface within which each collaborator can contribute his or her specific expertise to the NACS.

**5.3. Territorial strategy**

A second phase of territorialization, called territorial strategy, conducted through collaboration with the users of the public night space. The goal is to transmit, share and refine the general strategy through the real expertise of the territory's users. This third step enhances energy and environmental considerations through a social approach, and guides the evolution of cultural representations towards reasoned nocturnal atmospheres. The result is a precise cartography of expected atmospheres, allowing the implementation of operational documents prioritized in time and space. At the same time, it allows us to apprehend, directly from the lived space, the expectations and needs of individuals in terms of lighting ambiences. All these elements are grouped together in a specific digital cartographic support designed for the occasion, the NACS interface.

**6. NACS interface: decision support, collaboration and digital transition of night strategies.**

This collaborative approach is associated with an exclusive digital mapping tool, dedicated to the nocturnal strategy and to the wider dissemination of its issues. It is presented as a unique support for awareness, projection and collaboration on the topics of light transition, projected atmospheres and technical and political decisions to be taken. The device encourages synergy between all decision-makers, actors and users of the public night space, and facilitates decision support through a dynamic interactive system accessible to everyone.

Developed to provide a scalable and collaborative decision support system, NACS has the following values:

- The concept of a Scheme indicates a framing document for the lighting strategy on a metropolitan scale, which can accompany its implementation over the long term,
- The coherence approach is understood as spatial, temporal and of uses, on the scale of all living beings evolving outside at night. The nocturnal environment is adapted in order to respect a balance between human, fauna and flora activities according to ordinary and extraordinary cyclical criteria,

- The projection of the Ambiences places the planning of the development in a qualitative logic, where the photometric indicators adapt to the needs and activities, and not the opposite,

- The mobilization of the term nocturnal encourages the reintegration of a temporality, the night, and its natural resource, darkness. It encourages policy documents to move away from considerations exclusively motivated by a predefined amount of artificial lighting.

The case study analyzed in Brest is part of an exploratory approach to the nighttime environments experienced by citizens. In this respect, the collaborative approach is conducted directly from the digital interface, offering a transition from an existing panel of highly technical tools to a new generation didactic interface, dedicated to political, strategic and social considerations. Regarding the latter, the collaborative approach encourages the essential evolution of the user's posture, from spectator-consumer to actor of the nightlife of his territory, by providing a fine and daily expertise of use otherwise considered inaccessible.

# 7. Transversal diagnosis and general strategy of Brest Metropole

The transversal diagnosis of the nighttime atmosphere is carried out by mobilizing the following territorial data: public lighting heritage; road network; architectural and urban enhancement areas; historical monuments; natural areas; green and blue networks; schools. The data is obtained via the internal services of the metropolis, or online via an Opendata platform<fnref n="3" />.

## 7.1. Transversal diagnosis of Brest Metropole

Individually, these indicators represent uses and rhythms on the ground and require a certain amount of lighting, but cannot, on their own, become the exclusive determinants of a night-time strategy. When they are crossed, we obtain clues, particularly in terms of conflict between two rhythms and uses. For example, according to the normative and regulatory texts, a main traffic route requires a specific minimum amount of lighting. On the contrary, some natural areas expect little or no lighting. What strategy should be adopted when a major roadway crosses or borders a natural area: that of preserving a potentially unused lighting service or that of preserving the environment at the risk of exposing human beings to less comfortable atmospheres? At this point, the collaborative methodology, as much in the establishment of a shared vocabulary as in the identification and enhancement of nighttime rhythms, will be able to objectively and operationally accompany the choice of decision-makers and planners regarding the parameters of the expected nighttime ambiences. Among these parameters, we find, in order of importance:

1. Should lighting be used? If the answer is no, it is recommended to remove the equipment, or at least to remove the structural components (lamp, driver, electrical box),

2. If it is necessary to light, it is then necessary to know the current state of the equipment and its environment (road network, built environment, natural areas, etc.).

The acquisition of these elements is done by consulting, preparing and representing all the physical databases available on the territory. This step allows the transversal diagnosis to be carried out, which will determine the next step, called the general strategy.

<footnote n="3">³ For this study, we mobilized the Opendata Brest Métropole platform. [URL] : https://opendata.brest-metropole.fr/pages/accueil/ - last consultation on 06/08/2022.</footnote>
## 7.2. General strategy of Brest Metropole

The general strategy is developed around the crossing of territorial indicators. It mobilizes the photometric criteria determined in the ministerial order of 27 December 2018⁴ and offers a wider metropolitan distribution. Thus, the color temperatures of the sources adapt to the biodiversity environments, and lighting and extinction times to road categories (fig.2).

<figure><img src="image_6.png" /><figcaption>Figure 2: clockwise: (1) diagnosis of color temperatures (orange: 2200°K; yellow: 3000°K; cyan: 4500°K+), green and blue flat area: green and blue screen. (2) color temperature distribution strategy (orange: 2200°K; yellow: 3000°K), the lowest color temperatures are located near the natural areas. (3) midnight power level diagnosis (blue: 0%; cyan: 10%; green: 30%; orange: 60%; yellow: 100%). (4) power variation strategy at 00h (blue: 0%; cyan: 10%; green: 30%)</figcaption></figure>

The diagnostic process allows us to measure the important disparities between urban, natural and ambient structures. The color temperatures are distributed without visible pattern, and the dimming regimes do not seem to follow a precise territorial logic. Different factors appear to be at work:

- The evolution of lighting technologies: mercury vapor, now banned, high pressure sodium, with orange lighting, and metal halide, with yellow lighting.

- The creation and renovation of the lighting heritage, concentrated in certain areas and at certain periods.

At this point, the notion of rhythm raises the question of the phenomenon of desynchronization. The latter seems to occur between the major rhythms of the administration of public lighting, namely:

- Political, normative and regulatory decisions and their timetables.

- Technical and technological innovations encountered and implemented over the decades,

- The operations of creation and renovation of the heritage,

These three desynchronized rhythms produce ambiances scattered over the metropolis. The color temperatures, regularly linked to lighting technologies, do not respond to precise territorial structures

<footnote n="4">⁴ We refer to the ministerial order of December 27, 2018 on the prevention, reduction and limitation of light pollution. [URL] https://www.legifrance.gouv.fr/loda/id/JORFTEXT000037864346/ - last consultation on 06/08/2022.</footnote>
but rather to the political need to produce a lighting service that meets normative requirements, regardless of the resulting ambiance in terms of visual comfort. The light levels are determined according to a classification of motorized roads whose daily and seasonal cycles of use are mostly unknown. The recommendations made by NACS meet the current regulatory requirements, namely a reduction in light levels and color temperatures in the area of biodiversity. However, the knowledge in terms of fauna and flora species is weak, making the recommendations a partial response to environmental preservation issues.

### 7.3. *Limitations of the general strategy*

The desynchronization of the rhythms of decision, innovation and operation produces a nocturnal territory with resolutely heterogeneous atmospheres. Technical, political and regulatory priorities dominate and erase the mobilization of the criteria of the rhythms of users, fauna, flora and human beings. The general strategy proposed in Brest corresponds to a harmonization of the luminous ambiances with the contemporary environmental and energetic determinants but, like historically encountered practices, always remains at a distance from the needs and uses on the ground. However, this initial strategy phase allows for the building of a common language with the city's elected officials, who acquire a more detailed knowledge of the trajectory and challenges of artificial lighting. This initial pooling of expertise (political and technical) encourages rigorous decision-making that is adapted to the expectations of the energy and environmental transition of artificial lighting practices. Finally, this collaborative work allows to engage the territorial strategy with planners and citizens, through the NACS interface.

## 8. Brest Metropole's territorial strategy

The territorial strategy is considered as the element of synchronization of all the rhythms of decision, innovation and operation related to artificial lighting, around priority rhythms: nocturnal fauna, flora and human activities daily or cyclical.

### 8.1. *Synchronization around the ordinary and extraordinary rhythms of public space*

The identification of these uses is, in the case of Brest Metropole, determined by the collaboration of the different departments of the public space (interdepartmental collaboration) and by the mobilization of citizen panels (nocturnal territorialities). In order to facilitate the stages of contribution, representation and restitution of the participants, the digital interface of the NACS proposes a section for contribution and consultation of the transmitted data (fig. 3).

<figure><img src="image_7.png" /><figcaption>Figure 3 - On the left, the NACS interface enables a contribution to be made simultaneously with the general strategy observation. On the right, the contributions can be consulted in the form of pop-up displaying the content of the contribution.</figcaption></figure>

### 8.2. *First contributions to the territorial strategy of Brest Metropole*

In May 2022, the head of the public lighting department, Saïg Potard, accompanied a participatory initiative on public space, entitled exploratory walk of women in Kerourien. He collects the opinions of the mobilized women users and transcribes them via the NACS collaboration interface. At the same
time, he encourages the collaborators of the other departments of the metropolis to use the digital interface to analyze the general strategy and to comment on it when points of evolution are noticed. These initial comments are summarized in Table 1.

<table><caption>Tableau 1 - Contributions from the interdepartmental collaboration and citizen participation processes. Contribution from the Parks and Gardens department indicates a problem of respect for biodiversity. 7 citizen contributions provide observations of more or less comfortable atmospheres from the street.</caption><thead><tr><td>Observation</td><td>Process</td><td>Typology</td></tr></thead><tbody><tr><td>Issues with respect to biodiversity.</td><td>inter-service collaboration</td><td>Environment</td></tr><tr><td>Seen from the metro, the entrance to Kerourien is very dark: scary, not feeling like going to the area.</td><td>citizen participation</td><td>Representation</td></tr><tr><td>Porch on Amiral de Gueydon Street is well lit and safe. Women use this route because it is safer than the porch on Père Ricard Street.</td><td>citizen participation</td><td>Representation</td></tr><tr><td>Reassuring lighting, especially with the supermarket open late.</td><td>citizen participation</td><td>Representation</td></tr><tr><td>Playground "le rond" not lit + dark atmosphere of the Père Ricard street: rethink the lighting of this place.</td><td>citizen participation</td><td>Representation</td></tr><tr><td>Père Ricard street: lack of light / Review the light on the main street.</td><td>citizen participation</td><td>Use</td></tr><tr><td>Basketball area not lit / Possibility of lighting until 8pm?</td><td>citizen participation</td><td>Use</td></tr><tr><td>Unlit playground: request for playground lighting.</td><td>citizen participation</td><td>Use</td></tr></tbody></table>

## 8.3. Contribution analysis

We propose a classification of contributions by process (inter-service collaboration; citizen participation) and by typology (environment; representation; use). The typology environment focuses on the unidentified conflict areas between lighting practices and biodiversity preservation issues, in order to concretize the environmental transition of lighting practices. The representation typology gathers the citizens' contributions related to the feeling of security and well-being towards the lighting presence, considered as local cultural representation criteria. The use typology underlines the users' expectations in terms of lighting of some recreational equipment (playground), unusable in the evening due to lack of lighting.

## 8.4. Continuation of the territorial strategy

Undertaken in 2021 at the initiative of the head of the public lighting department in Brest, Saïg Potard, the NACS is simultaneously proceeding with the stages of general and territorial strategies. Framed by the rhythms of decision-making, the next participatory stages remain to be determined in terms of time, space and methodologies to be used. The SCAN approach is intended to be part of a long time perspective, dedicated to understanding the daily and occasional rhythms of all the territory's users, in order to adapt the political, technical and technological choices that are essential to a responsible practice of public lighting, thought out by and for the users.

## 8.5. The NACS methodology in the evolution of Brest Metropole's lighting policies

The general strategy of the SCAN is approved by a coordination committee made up of elected vice-presidents in various fields: territorial climate air and energy plan, services to the population, territorial proximity, urban planning, development, sensitive natural spaces, active mobility, mobility (public transport), urban tranquility, citizen participation.

The sharing of the challenges of each public policy, the pooling of their knowledge, thanks to the digital cartographic tool, allows the analysis of their respective impacts on street lighting and their collective weighting debated. This defines the general strategy of the SCAN. The territorial strategy is based on the field expertise of the users of the public space and also of the local elected officials (mayors of the
communes and districts of the city of Brest) which contributes to the definition of the general strategy. Each street lighting renovation or development project complies with the SCAN guidelines and includes the politically validated recommendations in terms of atmosphere: illumination level, color temperature, nighttime dimming profile of the illumination level.

Regarding the nighttime atmosphere resulting from the NACS recommendations, a post-renovation field survey is currently being considered in order to collect the perceptions of users before and after the evolution of the nighttime atmosphere.

## 9. Discussion

Light sobriety, through its social approach, is a political project. Driven by the notion of rhythms, this in-depth strategic work is part of a temporal process motivated by criteria of decision-making, financial, technical and innovation capacities, all grouped under the dominant notion of uses. The clues collected through the NACS open up priority operational actions (regulations, energy, environment) and socio-cultural approaches embedded in the constancy of a decisive philosophical approach: nocturnal atmospheres are able to meet complex and qualitative sensitive information, to open up to a quantitative and qualitative balancing and to reveal historical and new nocturnal atmospheres, where the rhythms of lighting, users and darkness cohabit in space and time.

The methodology undertaken in Brest Metropole hopes to ensure the transition from a top-down method, where the user is still absent from the collaborative loop, to a bottom-up method, where he is a contributor to the strategies. Its insertion is envisaged once the general strategy has been politically validated, with the aim of testing it in the field and determining the territorial scale, adapted to the needs and activities of each place. In this sense, and to use Arnstein's scale, we envisage a transition from tokenism to partnership. However, one of the most important unknowns lies in the individual desire to be mobilized around a question of ambiences with resolutely acquired fundamentals and potentially uncomfortable changes.

This methodology is being deployed in parallel in other French communities and underlines the desire of decision-makers and planners to reduce the amount of artificial light in order to achieve substantial energy savings, greater respect for biodiversity and to place their renovation programs in an accessible and controlled time frame. The collaborative approach and the digital tools make it possible to consider the simplified evolution of strategies for the nighttime ambience of specific territories, in line with political and technical developments, and with current and future cycles of daily, seasonal and generational use, with the aim of consolidating the dynamics of sober lighting, adapted to the uses and temporalities of the territory.

After decades of progress and innovation in favor of widely illuminated territories, and without any other consideration than the rhythms of economic growth and the extension of the duration of professional and recreational activities, the criteria of energy savings and environmental preservation open up unexpected social considerations to lighting practices. These considerations could potentially lead to the development of responsible practices of artificial lighting, motivated by a sensitive and qualitative expectation of night landscapes, shared and consolidated by the expertise of the users.

In terms of rhythms, which temporalities will be needed to rediscover balanced nocturnal atmospheres, whose dark resource will eventually present physiological, psychological and philosophical virtues?
## References

[1] Houel, N. (2020) La pédagogie de la sobriété lumineuse, thesis

[2] Falchi, F.; Cinzano, P.; Duriscoe, D.; Kyba, C.; Elvidge, C.; Baugh, K. ; Portnov, B. ; Rybnikova, N.; Furgoni, R. (2016). The new world atlas of artificial night sky brightness. Science Advances.

[3] Sanders, D., Frago, E., Kehoe, R. et al. (2021) A meta-analysis of biological impacts of artificial light at night. Nat Ecol Evol 5, 74–81.

[4] Challéat S., (2019), Sauver la nuit. Comment l'obscurité disparaît, ce que sa disparition fait au vivant, et comment la reconquérir, Paris, Premier Parallèle, 296 p.

[5] Franchomme, M., Hinnewinkel, C. (2019). Acceptabilité sociale de la trame noire : exemple de la Métropole Européenne de Lille.

[6] Paquot T. (2000). Le sentiment de la nuit urbaine aux XIXe et XXe siècles. In: Les Annales de la recherche urbaine, N°87. Nuits et lumières. pp. 6-14.

[7] Deleuil J.M.; Toussaint J.Y. (2000). De la sécurité à la publicité, l'art d'éclairer la ville. Les Annales de la Recherche Urbaine, PUCA, pp.52-58.

[8] Zielinska-Dabkowska, K.; Xavia, K.; Bobkowska, K. (2020). Assessment of Citizens' Actions against Light Pollution with Guidelines for Future Initiatives. Sustainability. 12. 4997.

[9] Chelkoff, G.; Bardyn J.L. (1990) Une approche qualitative de l'éclairage public. [Rapport de recherche] 17, CRESSON; GEG, pp.167.

[10] Deleuil J.M. (2009) Eclairer la ville autrement, expérimentations et innovations en éclairage public. Suisse. PPUR.

[11] Lefebvre H. (2004) Rhythmanalysis, space, time and everyday life. Bloomsbury Academic.

[12] Zielinska-Dabkowska K. ; Bobkowska K. (2022) Rethinking Sustainable Cities at Night: Paradigm Shifts in Urban Design and City Lighting. Sustainability. 14(10):6062.