Co-designing safe and sustainable darkness for northern urban places

The technological development, quantitative increase and qualitative design of urban lighting have succeeded in improving the safety and comfort of urban spaces. In this context, dark and dimly lit places appear as undesirable, even dangerous. However, the disadvantages of overlighting are increasingly being identified. On the other hand, darkness has well-being effects and aesthetic values in urban environments. The Safe and Sustainable Darkness project studies the frameworks for dimmer urban lighting: how to find room for lower lighting levels and darker places, respecting the diverse use of spaces and the values and experiences of city residents. In the article, we present participatory process for design and implementation of safe and sustainable urban darkness. The expertise and understanding of two different groups is of interest. Interviews of various professionals in the city organization reveal how illuminated and un-illuminated places are perceived from an administrative perspective. Inhabitants and users of urban space share their insight of the meanings, potential and context of the existing and future dark places. By combining the research material from interviews, crowdsourcing, workshops and evaluated pilot installation, we propose a co-design methodology to create enjoyable dimly lit and un-illuminated urban spaces.


Introduction
The technological development, quantitative increase and qualitative design of urban lighting have succeeded in improving the safety and comfort of urban spaces [1][2].In this context, dark and dimly lit places often appear as undesirable, even dangerous.However, the disadvantages of overlighting are increasingly being identified.Excessive lighting has a negative impact on the well-being of people and other organisms, as well as on ecological systems [3][4].This is leading to a paradigm shift of lighting design to better balance the amount of light brought into environments with the actual needs for lighting.Several recent papers identify the values of darkness as a necessary starting point for urban lighting design [5][6][7].Current research and practical applications of lighting design and intelligent lighting technologies such as presence sensitive lighting [8] seek methods to adapt lighting to the environmental conditions and needs of the users, also considering the requirements for different traffic forms.These include, for example, creating balance between brightness levels and reducing contrasts [9].The dark adaptation process of the human eye can also be taken as one of the design criteria [10][11].Aesthetic and cultural values of darkness are articulated in research and art [12][13].
This paper presents a case study developing a methodology of co-designing dark or dimly lit places in urban contexts, which are experienced as pleasant and safe.The case study is part of the Safe and Sustainable Darkness research project of the School of Architecture, University of Oulu, Finland.The general aim of the project is to develop and pilot a new and sustainable approach to the planning and implementation of lighting in northern urban environments.The goal is to optimize the use of low illuminance levels with the help of researched design solutions and intelligent lighting control 2 technology.Understanding users' experiences in dark environments and inclusion of participants in the process are in focus.The solutions for well-designed darkness and complementary lighting aim to reduce energy consumption in cities and provide tools to change design strategies towards carbon neutrality.The designed urban darkness gives space to the expressions of artistic light that support the experience of a safe and comfortable city.In the following sections, rationale for designing urban lighting and designing urban darkness is discussed briefly, as well as the concept of co-design.In the last section of the introduction, the aims of the study are presented.

Rationale for designing urban lighting and designing urban darkness
Artificial lighting enables urban activities to continue during dark period of the day, which is especially important in northern cities where the active part of the day extends to dark hours half a year.The task of urban lighting is to enable working, outdoor recreation, playing and other everyday activities even in the darkest months of winter.In a nocturnal city, the urban space is structured through lighting: landmarks, spatial hierarchies and conception of spaces can differ a lot from daylit situation.The lighting of the passageways improves movement safety and enables orientation for those moving in different ways and at different speeds [14].A large proportion of urban space users are afraid of using dark places, and lighting, on the other hand, is strongly justified by arguments related to street safety and sense of security [15].These apply besides streets, also places to stay, play, and spend time, like parks and recreation areas.
In urban lighting, the concept of sustainability concerns three aspects: ecological, economic, and social [16].From the ecological sustainability point of view, decreasing the amount of light in urban environments reduces both energy consumption and the recognized, harmful effects of excess light to nature and people [3].Economically sustainable lighting can be created only by evaluating the economic effects during the life cycle of different solutions.The role of lighting in supporting nocturnal economy must be recognized.To design socially sustainable dark and dimly lit urban environments, the principles of social sustainability of lighting solutions must be identified.Information based on up-to-date research on the connection between lighting quality and safety and the feeling of security is necessary.The essential questions are: What kind of darkness can be perceived as safe?What kind of places can be dark, when can it be dark, and what kind of interplay of light and darkness makes a place feel pleasant and safe?

Co-design
The social acceptability and sustainability of urban darkness can be approached through the theory of open city [17].The central idea of the theory is that a flexible and adaptable city -open to opportunities and flexible in challenges -can only be created by combining expert and non-expert understanding, as a collaboration of the entire community.Co-design or participatory design can be defined as design practice that involves different non-designers in various co-design activities throughout the design process.By non-designers it is referred to potential users, other external stakeholders, and people on the development team who are from disciplines other than design.Participatory design spans across a broad spectrum of domains and makes use of a broad repertoire of tools and techniques in commercial, community-oriented, and research contexts.Co-design activities can, optimally, be seen as multi-directional communication and interactive learning processes.Additionally, participation has been an important strategy in art.In contemporary participatory and community engaged art, some of the aims are: 1) to educate, activate and empower audiences; 2) to cede authorship in pursuit of a more egalitarian art; and 3) restoration of the social bond in a community [18][19].These are relevant viewpoints also in co-designing socially sustainable darkness.

Aims of the study
In this article, we present and reflect a case study of a participatory process for design and implementation of safe and sustainable urban darkness.The research process can be seen as an iterative cycle including methods for context and user experience study, ideation, scenario work, design, implementation, and evaluation.In this paper, we present a piloted model of all the phases in one chosen design site, but more research and iteration are needed to tune it according to context specific needs.The multidisciplinary background of the research group (arts and design, lighting design, architecture, humanities) gives us several viewpoints on expert and lay person co-operation and development of methods.
The key research question for the article is: What kind of methods are useful in combining lighting professionals' expert knowledge and citizens and other stakeholders' lay understanding of urban spaces, lighting conditions and the use of the city in the process of designing urban darkness?More specific research questions include the following: How to gather and use location specific understanding and local meanings, values, emotions, and imagination, and combine them with the more universal design principles and standards of high-quality urban lighting?How to fit together the unique needs and preferences of the individual city inhabitants with the demand for impartiality and equality?What kind of research and artistic methods are applicable?The process and the methods in each stage are discussed.The aim is that the proposed design process will result in valued urban places where artificial lighting is used only minimally and where is room for safe experiences of darkness.

Methods and materials
Methodologically our study situates within the field of design research, containing practical experimentation and design processes in a real-world setting including participation of local people and other stakeholders.Our research approach is exploratory [20] in-the-wild research [21].Exploratory studies aim to widen the scope of research by producing knowledge and insights about novel phenomena and by uncovering new research questions and hypotheses.In-the-wild user studies operate in a naturalistic, real-world settings and aim to capture everyday life user experiences.In our study, a mixed-methods approach [22] was followed, where qualitative, ethnographic inspired methods were combined with piloting, artistic methods, and design process, as well as qualitative and quantitative studies with luminance camera measurements.
The aim in our research is to develop a method for designing safe and comfortable dark urban environments by piloting a whole process of co-designing, implementing, and evaluating an intervention at one location.The time limit for project financing was set to year 2023.The lighting conditions in the north brought another imperative time frame for the implementation: half of the year would be without darkness.The changing lighting and snow conditions caused pressure on the process, but they were also essential from the point of view of research and design: these are the circumstances the proposed solutions must relate to.At the time of writing this article, the pilot project is nearing its end, but is not yet finished.Most of the actions have been conducted both in the snowy winter and in the snowless autumn.The most visible outcome of the process -the intervention during and after the Lumo Light Festival -was realized in November-December 2023.Thus, in this paper we are discussing still a work-in-progress and its preliminary findings.Analysis of the data collected during this project is still ongoing.
The design research project was divided into the following stages: 1) recognizing the dark places, 2) analysing the places, the user experiences, and needs, 3) co-designing the change, 4) realization of an intervention, and 5) evaluating the user experiences of the intervention, as well as the whole process and tested methods.The stages overlap in time.It was also evident from the beginning that a research design project is, by its nature, iterative.The understanding obtained during the process feeds not only the future steps but also loops backwards by reflections.
Designing urban darkness is tied to both urban planning (strategic planning, city structures and regulation) and urban space design [23].Finding socially accepted places for urban darkness can be seen as task of urban planning, whereas designing a socially accepted dark place in urban environment can be seen as urban design.The following chapters present the methods tried and planned in each stage of the case study research design project with the addition of the research of designing darkness in an administrative context.

Understanding the process in the city planning
The city of Oulu, which functioned as the research area, does not have -besides the lighting master plan -an actual city lighting strategy, nor a planning unit that focuses solely on city lighting.Planning and decision-making regarding light and lighting in urban space takes place as part of other construction processes, in several different units processing city planning, streets and traffic, building supervision, public buildings and large-scale city events.Forming a comprehensive understanding of the processes of urban lighting design in Oulu requires data collection from all these units.For this purpose, we selected 14 experts who are involved in planning and implementing the dark time urban environment for an interview.Since the main goal of this research has been to identify and understand previously unknown ways of thinking and acting related to planning processes and dark time urban environment, as well as the values behind them, we used an approach inspired by ethnography.The interviews were carried out as theme interviews, where the central themes were the design and decision-making processes included in the interviewee's work and the interviewee's conceptions of urban lighting as well as dim and dark urban spaces.In addition to this, we included in the interview such broader themes that we estimate are connected to the phenomenon under study and which can be used to create an interpretive context for the material.

Recognising the Dark Places
The first stage of the design research process was to recognize present and potential dark places in the urban areas of Oulu.We started to look for the dark places with the help of our own local knowledge and using different kinds of maps.Google Maps satellite images and National Geoportal [24] with its map layers were used to get an overall image of the city structure.Light pollution heat maps based on VIIRS/DMSP satellite data [25], and most importantly regional map service [26] with information on zoning and routes, current and near-future design and construction projects were studied to find areas where the amount of lighting has changed or might be changing significantly.
The research group carried out a mapping walk in each area selected for closer look in January-February 2023.A list of attention-directing questions was prepared for the walks.We discussed, took photos, described our observations, and wrote notes from the walks.Along all the walks there were both conventionally and particularly heavily illuminated sites and various dimly lit and dark places.
Using GIS, or geographic information system, provides an intuitive way to ask questions about specific locations and to respond on a map.Map-based questionnaires have been used in urban darkness development in the northern Europe at least by the cities of Helsinki [27][28] and Tallinn [29].In our research project, the first of two GIS surveys is aimed primarily at recognizing dark places.City dwellers are asked to mark on the map places that are important to them in daylight and in dark hours; pleasantly or unpleasantly dim and dark places; places that are pleasantly or unpleasantly luminous during the dark hours; and places where they have noticed disturbing or unnecessary light.Verbal justifications are requested for the entries.The aim of the survey is to identify dark places that are relevant to local people and to gather understanding of the experiences of darkness in the city.The survey also includes thematic questions on the meanings of darkness.Some of the questions are designed to give context for the interpretation.Both GIS surveys are timed so that there will be responses given in the autumn before snow falls, and also during the winter with the snow.In this way, comparison data on the effect of snow cover can be obtained.Surveys are carried out on the Maptionnaire platform.(www.maptionnaire.com)

Analysing the dark places
After locating some interesting dark places using maps and walks, we started the context study.The aim was to understand the current situation and characteristics of these locations, analyse their current and potential usage, define the needed change, and find possible limitations for design.This included acquisition of both expert and lay understanding of the dark places under study.

Walking interviews.
To gain a better understanding of the city dwellers' perceptions of the dark and dim urban environment, we created three different routes for walking interviews based on our own mapping walks.Two of the walking interviews were carried out in March, while the snow was still on the ground, one had to be cancelled.Interview on the most interesting route was repeated in October before the arrival of new snow.Walking with the subject has a long tradition in ethnography.It is a method that can be used to obtain versatile, multisensory information about places [30][31].In this study, the walking interviews were carried out in groups of three to eight participants.Each of the researchers had a pre-agreed role during the walk and the walks were captured as audio recordings.The walking interview participants were asked context-creating questions about their relationship to the area, conceptions of the area in different seasons and different light conditions, as well as personally experienced meanings of darkness and lighting.In addition to this, there were short stops at pre-planned locations, where the participants were asked to point out and tell about things related to lighting and darkness that they found pleasant, unpleasant or difficult to comprehend in the environment.The indications were photographed.There were also two longer stops along each walk, where the participants were encouraged to discuss what kind of atmosphere the lighting creates in the place, how they experience it in relation to the functionality of the place, and how the observed lighting could be developed or changed.Around the middle of the route, we stopped at an unlit place, where one of the researchers guided a multisensory perception exercise.The purpose of this was to give time for the vision to adapt to a dim lighting level and to evoke perception and interpretation of the environment beyond everyday habits.The walking interviews lasted about one and a half hours.At the end of the walk, participants were offered refreshments and the opportunity to ask questions, discuss the experience and give feedback.

Luminance camera measurements and visual-spatial analysis.
Besides the qualitative mapping walks by researchers and walking interviews with participants, we developed and tested a luminancebased method of measuring and analysing the visual-spatial light appearance in dimly lit environments in urban contexts.Luminance images were taken and produced with a calibrated digital camera and relating software in selected locations along the walking routes.The images were shot in March when a new layer of snow had just fallen over the already snowy ground and then again in October with dark snowless ground.We carried out visual-spatial analysis of the luminance images applying concepts inspired by morphological studies of essential elements of architecture [32] and the theory of space and light [33].Our method was based on the recognition of certain parts and elements of space in the views made visible by distribution of luminances in the images, as well as the relation of the user of the space to the dark and light areas within the view.In addition, several tools of the analysis program were applied for the quantitative analysis of the images, framed by the visual-spatial analysis.For detailed information of the procedure, technology, and analysis method, see [34].

GIS crowdsourcing.
The second GIS survey is tied even more directly to experiencing a unique place.This survey not only refines and concretizes the information produced by the more general survey, but also collects ideas for change.Respondents are given six predefined routes with certain places to evaluate.There is also a possibility to draw an own route.The survey is designed to be quick and smooth to answer as the respondents use smartphones to fill it during the walk, while on location.The questions at the places to evaluate concern the current and potential use of the place; the atmosphere; perception of the lighting condition; feeling of safety; and ideas for improving the place.Responses can be enriched with photos.

Co-designing and realising the intervention
Realizing a temporary intervention is a way to test and demonstrate public acceptance of urban darkness [6].Co-designing an intervention ensures that ideas, needs, hopes and fears of people using the place are met in the design.In our design research the intervention serves also to test the participatory methods.A newly renewed park in the vicinity of the city centre was chosen as the location for the intervention.The area is bounded by the sea on one side, and by residential area on the other sides.A brightly illuminated fast-cycling lane cuts the park.There are several functional places in the park, namely children's playground and traffic park, outdoor gym, parkour and skate parks, small marina, art pieces, and barbecue place.Not counting the playground, none of these is in active use during the wintertime -a great deal of the potential of the park remains untapped.Co-operation with the city of Oulu made it possible to start the intervention during the annual Lumo Light Festival, a context that gives it publicity and raises wide interest, and continue it for a month after the festival.
To better understand the use of the park and to identify different user groups, we did some background research using open online sources, interviews, and ethnographical observation of the park.Different workshop concepts for the co-designing process were planned next: Playing with Light, Dark Adaptation and Co-Design Workshop Series.Each of these has its own goal, and they aim to involve different groups of people.The workshops were held in October-November, mostly outdoors at evening twilight and dark hours.One of the researchers directed the workshops, and the others documented and observed the work.
Playing with Light Workshop was organized in the playground, first for a group of children from a nearby kindergarten and then twice during the Lumo Light Festival.The children, accompanied by their parents, explored the familiar environment in the dark, helping the researchers find darkness and play with it.They were then encouraged to illuminate the playground with portable lights.Dark Adaptation Workshops were planned to be held on an unlit island in front of the park.The idea was to let participants explore moving between brighter and darker environments, to experience dark Figure 1.Intervention and workshops focus areas in the Hollihaka park: 1) un-lit Sonnisaari island, 2) children's playground, 3) traffic park and 4) parkour and skate parks and 5) fast-cycling lane and pedestrian walkway.Background map from [24], photos and image processing by the authors.adaptation and sensations it evokes and to be together and co-operate in darkness.Unfortunately, unexpected construction work started at the island and the planned workshops had to be cancelled.
The goal of the Co-Design Workshop series was to develop the intervention together with the participants.The series begun with the creation of scenarios related to the use of the site and proceeded through on-site experimenting to an implementation influenced by the process.After studying multiple possibilities and aspects, the researchers decided to place the intervention in the parkour area of the park.The permanent lighting of the area was switched off and 27 individually controlled RGB architectural lighting fixtures were installed instead.Temporal dynamics of light and darkness were worked on in the series' last workshop.The final intervention consists of 15 smoothly looping lighting scenes that present alternative ways to light the place.There are three different sets of scenes: shades of white, inspiration from wintertime natural light, and dashing colours.

Evaluation of the intervention
The intervention was to be evaluated mostly by using the same methods that have been in use earlier in the design process.There was a digital survey that visitors can launch using QR-codes while on location.The context of light festival gave the intervention and the survey a possibility to reach wide publicity and audience.Deeper thoughts about the change in lighting of the place were gathered by organizing a walking interview for urban planning and lighting experts.Luminance measurement photographs were taken and will be analysed in relation to the measurements taken before the intervention.All evaluation is tied to the actual place and experience as closely as possible.Themes of interest are functionality and experientiality, social dimensions, atmosphere, and aesthetic qualities of the dimmer place.All these include the element of safety and security.

Results of the tested design process
The different methods of design research have been described above.Most were tested during the first quarter of the year and the research continued in the autumn when nights got darker again.Results of the methods tested in spring and preliminary results of those tried in autumn are given below.

Incremental understanding of the processes in the city planning
One essential goal of the expert interviews was to identify key points and roles in the decision-making process regarding the dark time urban environment.The material collected provides good tools for this.The interviews also opened us to understand that it is not only essential who makes decisions and when, but also how decision-making takes place.The interviewed experts often described their work as a negotiation between parties representing different interests.Because of this, the resulting urban space is always some kind of compromise.Consistency in decision-making appears as a central value guiding the work of experts.Since there are no written instructions for everything, experts look for support, coherence, and equality for their own solutions by examining previous implementations, reasonings, and decisions.It seems that these practices significantly guide the formation of urban space.Practices evolve over a relatively long period of time and slowly change by repeating and producing examples of different decisions and their consequences.The observation strengthens the view that experiments and piloting of research projects can really serve as necessary examples that experts can lean on in their decision-making.Conducting the interviews also made us realize that asking questions was probably the most effective way to get the experts' attention to the project's goals, even though we did not primarily aim for that with the interviews.Asking the city representatives to tell us their own perspectives made them think intensively and tangibly about the theme of light and dark.

Recognising the dark places
Based on satellite images and other map data, it appeared that in some parts of the coastal area the lighting had become more intense as a result of the construction of a fast-cycling lane.On the other hand, the sea element brought the dark areas right next to the urban centre, and the inhabited islands in IOP Publishing doi:10.1088/1755-1315/1320/1/0120048 front of the city were clearly darker than the rest of the urban area.The fast-cycling lane will continue through these islands, and a completely new district is being built near them.We selected three different areas for more detailed mapping: the waterfront area of the city centre, where the intensity of lighting varies greatly, some of the islands with many currently dark places, and thirdly a typical Nordic suburb inland, that stood out slightly less bright than other similar districts.The suburb's lighting will be renewed in the next few years.The researcher mapping walks highlighted how moods stagger and change, how places relate to each other, and how the same places appear different when examined from within, compared with how they seem from further away.Based on our experience it is essential to consciously reflect on these perspectives formed during the mapping walks, as they are used in many ways at different stages of the process.In a research situation, such as walking interviews, researchers' own interpretations and preferences should not be transmitted to the subjects, while in the co-design process, these perceptions are needed as researcher's contribution to the shared design.The choice of the coastal park for the place of the intervention was based on the mapping walks.The walks affirmed that continuing research in the other pre-selected areas is justifiable and gave us understanding to create the framework for qualitative analysis of luminance measurements.

Walking interviews
With walking interviews organized for lay persons, we tested several different research methods.This made the experiments multi-level and partly complex.Determining the route and locations of stops in advance, as well as the implementation of walks in groups, have been central to the experiments.The walking interview itself is a method that brings uncontrollable events and disturbances from the environment into the interview.A group interview further increases this uncontrollability, as the group dynamics that arise between the subjects affects the general atmosphere and the subjects' desire and courage to express themselves.In the conducted walking interviews, a good method for reducing the influence of the group was found by occasionally dividing the walking interview into a conversation between one or two subjects and a researcher.By combining an individual interview with the group situation, even the more withdrawn group members got the opportunity to speak their views freely.
Conducting the walking interviews confirmed that placing different research methods in suitable environments and encouraging subjects to examine the environment with an open mind requires a precise script.A pre-selected route with pre-selected stops does not produce the same information as a walking interview where the subject chooses the route and the stops.In this case, however, the choice proved fruitful, as it took the subjects to places they would not normally go during the dark.Interestingly, these places along the route were not obscure back alleys, but unlit small forests by the sea -actively used areas that are perceived as pleasant and appreciated in the light of day.It is also interesting that going into the dark small forest or "thicket", as one participant called it, was not necessarily talked about as a scary thing.Instead, the expressions used, and the tone of the speech convey the perceived irrationality of this act.Going into an unlit small forest seems to require a special reason or explanation, such as walking a dog or a route that is deliberately designated as a dark area.It seems that in addition to possible fear, moving in unusual places at unusual times can make the person themselves appear odd and therefore potentially threatening to others.Taking the research subjects to an unlit small forest also brought out that city dwellers do not necessarily have any experience of moving in an unlit environment.Even those who move around the areas, for example jogging or cycling, often carry a headlamp or other strong light source with them, and therefore have never tried moving around the areas without lighting.Viewed from a strongly lit area, the surroundings can easily look pitch dark.However, a joint perception exercise in the small forest showed that the unlit place was not dark, but quite pleasantly dim.The observation surprised the participants and gave us an idea of demonstrating dark adaptation to city dwellers as part of the later intervention.
We will continue to develop walking interviews by categorizing the different aims and by creating different concepts for different needs: 1) general, ethnography-influenced research walks to find out local cultural, historical, climatic and environment related meanings and values of darkness, 2) more specific design walks for analysing specific places and the needs, hopes, fears, ideas, and attitudes IOP Publishing doi:10.1088/1755-1315/1320/1/0120049 people using these places carry, 3) evaluation walks in places where lighting conditions have been changed and comparative information about the conditions before and after the change is available, and 4) less profound and more entertaining evaluating event walks making it possible to host much larger groups of participants.To gain more versatile understanding of the experiences of dark urban environments dedicated walks should be arranged also for groups with special needs or backgrounds.

Qualitative analysis of luminance measurements
According to the preliminary results of the luminance analysis, the chosen visual-spatial conceptsenclosure, open view, interspaces, framing, scale, detailing and user relation -that were tested in creating the analysis images, seem to be useful conceptual tools for framing quantitative analysis of complex luminance images of urban darkness.Comparing the measured luminance values to the visual-spatial analysis and on-site experiences helps a designer to understand the relation of the measured luminances to the design intentions and possible positive and negative experiences within complex urban environments.The method seems promising as a research tool, as well, in analysis and evaluation processes to understand users' experiences of dark environments.Additionally, it could be applied in co-design processes to illustrate participants' concepts of urban darkness [34].

Preliminary results of the workshops, intervention, and evaluation
When writing this, the experimenting and co-designing workshops have just been conducted and the intervention launched.The analysing process has just begun.Background research played an important role in identifying the target groups for workshops and creating contacts with them.We see the Playing with Light Workshops for children as possibilities to gather physically smaller and culturally not-so-informed persons' experiences of dark urban space and see if some products of their playful imagination could be implemented in the design.For the Dark Adaptation Workshops, which were unfortunately cancelled, our expectation was that they could have given us insight on solutions for transitional zones between bright illumination and darkness [10] and ideas on how to encourage people to explore dark adaptation.Testing these two themes, dark adaptation and playful imagination, in separate workshop concepts also gave us more practical understanding on how to include them in the progressive Co-Design Workshop Series in which the temporary intervention was developed.The workshop series proved to be an interactive learning process we shared with the participants.Concrete working on darkness enabled previously unconscious attitudes to be put into words more easily.All parties generated new local understanding and new ways to experience, think and utilize darkness.Cocreation in a playful setting also deepened our understanding of how to work with darkness and light on multiple layers of human comprehension, such as analytical, sensory, bodily, and social.

Discussion: Forming a proposal for an urban darkness design method
Darkness is relative.Brightness, dimness, and darkness form a nuanced scale that could be utilized in urban lighting much more efficiently than today.The lighting conditions in northern outdoor spaces are in constant change.They are affected by the time of year and day, weather, and snow condition.We see it as important to look at the question from different points of view, thus, on-location methods, GIS crowdsourcing, quantitative studies, qualitative luminance analysis and ethnographical understanding complement each other.To gain sustainable design solutions that authentically serve multifaceted user needs, it is important to use several forms of information and knowledge.Later in the research we will compare the results of these participatory and qualitative methods with the current quantitative design principles and standards.The aim will be to evaluate the appropriateness of quantitative regulation regarding sustainable lighting and sustainable darkness.
The values of darkness have been proposed as central guiding principles for designing sustainable lighting.We see values not only generic and abstract, but strongly bound with the local environment and society.The co-design and ethnographic approach we suggest here keep the values of darkness under discussion throughout the whole process, reflected and negotiated in every stage of the design process.The strategy is to apply multiple methods in multiple stages to raise both analytical and experience-based awareness of the importance of safe and sustainable darkness.Efforts to combine expert knowledge and layperson knowledge appear multi-layered, especially when discussing the dark and dim urban spaces.In cities where there is no specially designated urban darkness coordinator, urban lighting is basically something planned, but the absence of lighting is usually unplanned or a byproduct of lighting design.Therefore, darkness as an asset is an issue that is rarely or not at all addressed in the work of experts responsible for planning urban environments.Because of this, it is difficult to name experts in the dark and dim urban spaces.Even though an expert has knowledge of planning processes or a systematic way of looking at the urban environment that differs from laypeople, in their experiences of the dark, experts are also laypersons.Therefore, the expert knowledge and lay knowledge collected in this study can be viewed as a continuum and not as opposites.Personal experience can be seen as a valuable part of expertise when used as a tool for empathic understanding of users.More conscious deployment of this perspective could be to bring user orientation earlier into the design processes.However, we believe that the continuity between lay knowledge and expert knowledge should also be developed through defining and strengthening expertise, as a sustainable dark urban environment can only be the result of conscious planning.
Designing urban darkness is an iterative process that is implemented on different levels.Our case study was conducted mostly on a very concrete level, leading to an intervention in a park.However, there is yet another, more strategic level which needs to be more deeply scrutinized in the future.In our study, this level problematics was revealed especially in the expert interviews.The importance of long-term objectives and principles that have been confirmed at various policy levels was evident.We argue that this should be advanced by bringing darkness to conscious attention alongside lighting in the design and planning processes.We assume that undulating the theme between the very concrete level of urban place design and the more strategic levels of urban planning, regulation, and governance, helps to consolidate sustainable darkness and sustainable lighting in the societies.Furthermore, we see piloting as a powerful tool to change practises.This underlines the need for cooperation between cities and research institutions, as well as engaging new agents like artists and consultants with ethnographic understanding into design processes.

Figure 2 .
Figure 2. On the left: children trying to catch escaping shadows in Playing with Light workshop.In the centre and on the right: two of the 15 scenes of the intervention.Photos by the authors.

Figure 3 .
Figure 3.The proposed methods situated on different stages of an iterative design research project and utilizing either or both expert and lay understanding for design purposes.Diagram by the authors.