The document discusses a research project by an Urban Lighting task group to develop innovative urban lighting strategies based on scientific evidence. The group aims to test their framework through a tactical lighting intervention in an urban park in Barcelona. Their approach focuses on using darkness as an asset to minimize health impacts while providing adequate lighting when needed through spectral tuning and wireless controls. The research questions how to identify objective urban lighting guidelines that promote ecological health and environmental justice while ensuring smart lighting is only used for these purposes, not surveillance. The group will test their prototypes and strategies in the park as a controlled experiment before proposing a larger intervention.

1. Urban-Centric Lighting Task Group: Tactical Lighting as an
innovation strategy
Abstract. The present article describes a perspective on tactical urban lighting and its power as
a source for disruption and innovation in the field of urban lighting. A tactical, lightweight
intervention in an urban green area is designed to implement, test, and communicate these
innovative methods. The research project is being carried out by a task group formed by
professionals from different companies in the form of a real-world experience in public space.
Such methods and technologies are an application of the evidence-based knowledge in the field
of artificial lighting for the sake of health and well-being. There is also a fundamental source of
awareness that comes from social sciences about how the built environment design promotes
well-being, or else constitutes a hazard for health.
After a definition phase for the methodologies and the technology that would need to be
developed, the task group is focused on prototyping new products and planning a tactical
intervention on a real urban playground.
Having received support from local’s regional government innovation programmes, through a
competitiveness strengthening initiative, the project is partly funded by the European
Commission.
1. Introduction
Urban-centric lighting is the research topic of an Urban Lighting task group. The group was formed to
carry out research about the influence of urban exterior lighting in people’s health. This applied research
is being carried out by technicians, planners, managers and designers from different private companies
and public institutions, with responsibility and objective markets centered in public lighting and urban
planning. The project is located in the Metropolitan Region of Barcelona.
To start with, it is detected that an extended definition of health needs to be agreed, in order to drive
the evolution of the research and set proper foundations for the methodology. This definition of health
would comprise, for human beings, such “a state of physical, mental and social well-being, and not only
the absence of disease and infirmity”, as defined by World Health Organization, no matter how vague
or generic this definition will appear for our purposes [1]. The scope of our definition of such well-being
includes other living species, and of course, the urban space as an ecosystem, both natural and social.
From the biological perspective, the framework must apply the knowledge and scientific evidence
about the non-visual effects of lighting on mental and physical health and has the parameters that involve
this interaction identified and quantized. This effects on health and behavior have been studied and
demonstrated on humans, animals, insects, and plants, so there is a founded consciousness about the
harmful effects of light at night on living organisms. The framework will have to be aimed to minimize
such disruptions.

2. The perspective of social well-being is based on subjective perceptions and also on the human-space
interaction dynamics. Affection, subjective perception of trust, sense of belonging, among others, are
successful indicators for such values. We include under this title the perspective offered by the
environmental justice movement [2], as an analytical toolset to address situations involving inequality
in the public realm.
There is also an important ecological framework to consider. The need for more and better access to
green areas in cities is influencing urban planning evolution, so this ecological perspective will become
more necessary as the naturalization of urban spaces advances.
2. Objectives
The main purpose of this project is to evaluate and discriminate the objective parameters that will define
the lighting design and its features, choosing among the available technological innovation those that
are properly grounded on scientific evidence.
At the same time, there is research and innovation that come from disciplines such as ecology,
environmental psychology, critical urban studies, and sociology, that are strictly necessary to nurture
with sense and meaning design decisions in the urban realm. They have given the knowledge for
establishing critical approaches such as gender perspective and environmental justice awareness, among
others. Such approaches should be included in the toolset for the building of an innovative
methodological framework. This why we need to identify and evaluate inclusive lighting strategies on
urban space, to avoid those that drive in an unequal or unjust result for reason of gender, race, age, or
socio-economic status, is another objective of the research.
The task group is collaborating with Barcelona City Council’s office for mobility, to implement one
experimental lighting project in the temporary arrangement of Gran Via de les Corts Catalanes Avenue.
The new place now reclaimed for pedestrian and civic use comprises 15.000 sqm that have been freed
after the inauguration of the new Glories Tunnel that diverts the heavy traffic under Glories Square. The
definitive project for this space is still being defined, so the place will remain in a temporary state for at
least two years. Joining forces with municipality will allow the group to experiment the framework with
a temporary lighting intervention that applies the results of the research on a real urban playground.
Figure 1. Conceptual Section of Lighting scheme for the temporary arrangement in Gran Via

3. Figure 2. Temporary Project for Gran Via: Plan View
3. Theoretical background
The group has summarized the available, state-of-the-art, sources of relevant knowledge that will
influence the design decisions regarding the urban intervention:
3.1. Tactical Urbanism and temporary projects
Short-term street interventions are frequently interpreted as a performative action by users, and work as
starting point for interaction between people and places [3][4]. They are recommended as a practice for
making better long-term planning decisions in urban space, and immediately influences a more positive
perception of it [5]. They are also powerful in terms of social engagement and communication strategy.
During the COVID-19 pandemic, a considerable amount of innovative temporary urban infrastructures
helped to partially deal with the challenges that the situation brought up. Contemporary urban planning
approaches that are focused on environmental health and sustainability, agree in the need of enhancing
the quality of life in the city through eliminating car transit and gaining space for pedestrian use. There
is a new demand for soft mobility and community-based urban services that addresses the convenience
of distributing mixed-uses and proximity services, avoiding the concentration and monoculture of uses,
with an arrangement that will result in the availability of all the services that contemporary city life
needs within walkable or biking distance [6].
Figure 3. Barcelona’s Superblock: Tactical Urbanism applied to a project of urban retrofit.

4. The superblock model that cities like Barcelona are applying impacts mobility, reducing car transit,
and establishing reduced speed (10 Km/h) areas [7]. As a way of introducing these changes, the
government is using the codes of temporary interventions (also known as Tactical Urbanism), to
understand the viability of the new design and communicate the project to its neighbours and
stakeholders [8]. The pilot program has come to an end, and now a major renovation is in progress, an
evolution of the initial concept that will establish green mobility infrastructures (the “Green Axis”) that
go beyond the superblock scale.
Urban lighting that focuses on the demands of traditional mobility has been dominant over the years
and has created urban nightscapes that are both unhealthy and unappealing. This is the present situation
in most of our cities: uniform, high light levels aimed to deliver visual needs of high-speed transit of
vehicles. When mobility is challenged in such a way that speed is drastically reduced and traffic density
is expelled from the city centres and residential neighbourhoods, such visual features are no longer
needed. The reduction in speed goes together with a reduction in the requirements of the visual task.
The time that we spend inside the space is longer. Lighting strategies deserve to be challenged, at least
with the same strength. And with more time to experience places, visual needs are different: there is
room for adaptation to lower levels, to enjoy the balance between light and shade, even darkness, without
risk of having an accident.
Figure 4. Primary temporary arrangement of Gran Via segment before the tunnel was finished and the
first phase of the new urban retrofit (the tactical project that is currently in-progress). Temporary
urban lighting is still addressed to traffic lighting and will be modified in the mid term.

5. 3.2. The growing dark-green
Target number 7 of the Goal 11 of the UN Sustainable Development Goals 2030 states: “provide
universal access to safe, inclusive and accessible, green and public spaces, in particular for women and
children, older persons and persons with disabilities”. The policy of developing and providing proximity
green spaces will therefore mean the naturalisation of the urban space, or the urbanisation of the natural
environment. In both cases, the green areas will behave as darkness repositories at night, for the sake of
the vegetation and fauna, but also to enhance human well-being and reduce light pollution. A concept
that has been developed by Roger Narboni at Agence Concepto, under the global name of “dark
infrastructure” [9].
3.3. Non-visual effects of artificial lighting
Human-Centric Lighting has framed design strategies and technology developments to address the non-
visual effects of lighting in humans inside the built environment. The discoveries around the potential
of lighting as a circadian stimulus [10], combined with a growing awareness about how the way a space
is designed has effects on human health and wellbeing, have caused an evolution that has been focused
mainly on the field of interior lighting, as the built interiors are the places where most of the artificial
light is applied to humans [11].
3.4. Lighting control to address light pollution reduction
The adoption of highly efficient LED technology in public lighting is just a technology replacement,
and not a solution to the extreme amount of light emission and light pollution of the night sky. Without
a change in methodology, a shift in the practice that is grounded on theory and experimentation, non-
visual effects on light, circadian disruption and other environmental threats will not be deactivated.
3.5. Environmental Justice framework
It is empirically demonstrated that significant levels of light pollution are associated to lower income
neighbourhoods [12]. There is social inequity in exposure to hazardous light levels at night, and dark
skies are considered as an amenity that is not within reach for everybody, while crime prevention or
reduction is the main excuse for over lighting, without an empirical demonstration of its benefits for it,
except for a topical (and arguable) sense of perceived safety when we are in a more lit environment.
Here the confusion lays between our ability to read and understand the surrounding space (quality) and
the amount of light (quantity). The reduction of such threat for health is also an urgent claim for social
justice.
Tackling gender inequities in urban lighting design will include giving visibility to women in public
space, and to gender-associated activities. Granting physical and mental security can be sustained
through an overall perception and understanding of the environment, that results in a global perception
of safety. [13]
Some of the innovation oriented to the connectivity of public lighting is devoted purposely on control
and surveillance technology. This results on hybrid devices where the lighting side is only one feature
among others. The technology and connectivity that is supposedly planned to enhance management and
efficiency, is also able to constitute a platform for sensible data gathering. The urban green space (or
common space) should be free of such technological threats. There are strategies to smartly save energy
and limit light pollution through simple, unmonitored control networks. So, the new green deal for
fighting the climate change does not justify any more such highly technological deployments and the
potential amount of data exchange.
The above considerations constitute the framework that is guiding the design decisions and the
development of the technology that will be applied to the experimental intervention.

6. 4. Research questions
- Is it possible to identify a set of tools appliable to urban lighting design that is objective and
represents an evolution in terms of ecological health and environmental justice for our cities?
- How can a set of guidelines guarantee the minimum biological interference with the living
organisms in an urban environment?
- How smart does a city lighting system need to be for environmental purposes and for health
purposes?
- What will be the evolution of the growing need for darkness in the intersection of human and
natural spaces?
5. Setting the technical requirements
Once the framework is set, and prior to the major intervention in the temporary urban project of Gran
Via in Barcelona, a beta-test is agreed. As the Gran Via project is having calendar issues, and is not
ready for an intervention in April 2022, the decision is that a test is to be carried out in a more controlled
environment. This beta-project will be installed in Parc del Molinet, a green public space just nearby the
Besòs River, that creates a natural frontier between the cities of Barcelona and Santa Coloma de
Gramanet.
Figure 5. Parc del Molinet is a urban infrastructure inaugurated in 1989. The lighting was renewed
once since that date, but LED technology is still not applied.
The place was built and is currently maintained by AMB (Area Metropolitana de Barcelona), and it was
designed by Arriola and Fiol Arquitectes. The AMB is the public administration of the metropolitan
area of Barcelona, a large urban conurbation made up with 36 municipalities. AMB is a supra-local
institution that, among other attributions, manages, plans, and makes urban and mobility projects at a
metropolitan level. As they have not made the transition to LED lighting on their infrastructure, they are

7. very interested also in exploring the framework to apply it in the future, mostly for parks and green
areas, a scope that is covered by our research. For the task group this applied exercise will serve as an
opportunity for testing technology and also methodology, in a relatively controlled environment, at
urban level but with a lower density and much softer requirements.
5.1. Dark resources
The main strategy follows the concept of darkness as an asset, as part of the infrastructure. For the sake
of a healthier environment, lighting is applied only where, when, and why it’s needed.
Instead of completely switching off lighting, a background level is set of spectrally-tuned lighting
that minimizes Circadian effects on humans and fauna.
Figure 6. Summary output for the Kumux Spectral design software, representing a spectral blend that
minimizes circadian effects while keeping color rendering and a reasonably good efficiency.

8. 5.2. Spectral tuning and blending
The software used for Spectral tuning summarizes the objective parameters of a light source in relation
with measurable qualities, such as color rendering, CCT, and circadian properties. It can work with
combinations of different LED sources, that are modelled by their spectral power distribution.
Equivalent Daylight Illuminance (MEDI) is the parameter that we have chosen to guide the spectral
contents of the resultant mixed-spectrum. A prototype set of lighting fixtures developed on purpose for
the project, have been set to use two pairs of combinations: a mix of PC-Amber and 3000K LED arrays,
and 2200K and 3000K LED arrays are mounted in standard urban fixtures, controlled by wireless
network devices.
Figure 7. The prototypes developed blend two different light sources: for both protecting living
species and providing good colour rendition, depending on the use of the space.
5.3. Control strategy
The control network is fed with the signal that comes from presence detectors that will activate a change
in the basic lighting when people come to the vicinity of the lighted area. When nobody stays around or
passes by the installation, lighting is restricted in level and spectral composition, so it will minimize
hazard for humans and other living species. This means, in terms of MEDI, that a maximum of 10 lux
is recommended at dusk and only 1 lux at night. Using a combination of PC-Amber and 3000K white
light blended source, this will allow us to have up to 15 (fotopic) lux at dusk and evening with only 7
lux MEDI (Figure 5).
This strategy means that visitors would be able to perceive the structure of the space when they are
approaching it, and will be accompanied by whiter, better rendering lighting when they decide to stay
at the place. This way, biological hazard is minimized, and only present (reduced to its minimum
expression) when is absolutely needed.
The main feature here is that the control network can work unmonitored and disconnected from any
hub or repeater, so the data generated never is ‘spilled’ out of the place. These autonomous wireless
networks allow for complex programming, and they provide the exact amount of automation for energy
efficiency, circadian disruption avoidance and light pollution purposes.
The use of smooth transitions between lighting states will provide people with a gentle mood of the
place, as light is controlled for creating a better experience of the space, and not merely for control
purposes.

9. 6. Provisory conclusions and further development
The research project is ongoing, and it is planned to be running in its first placement as soon as June of
2022. The basis for the framework is established, and the results will be gathered and evaluated in the
next months. There is still no calendar agreed for the tactical intervention in Barcelona, and the major
challenges that the group wants to bring to light are to be tested and negotiated with the local authorities.
This are mainly focused in the use of commissioned darkness, justified with the reduction of traffic
speed, and local network wireless technology, including the use of presence sensors. Local authorities
are usually reluctant to the use of sensors and devices alike, although dimming is already established
and accepted, it is not in a responsive manner or in-demand. The positive results in the beta test will
serve as a foundation for the conversation, as it will be the political intention to address the sustainability
challenges that the present is bringing to the attention of technicians, designers and planners.
References
[1] Boyce, P R 2010 The impact of light in buildings on human health Indoor and built
environment 19 https://doi.org/10.1177/1420326X09358028
[2] Colsa Perez, A et al 2015 Evolution of the environmental justice movement: activism,
formalization and differentiation Environmental research letters 10 https://doi.org/10.1088/1748-
9326/10/10/105002
[3] Killing Architects Urban Tactics – Temporary interventions + long term planning
https://issuu.com/alisonkilling/docs/urbantactics_tempinterventions_longtermplanning/8
[4] Street Plans Collaborative Tactical Urbanism Vol. 1 and Vol. 2
https://issuu.com/streetplanscollaborative/docs/tactical_urbanism_vol.1
https://issuu.com/streetplanscollaborative/docs/tactical_urbanism_vol_2_final
[5] Roe J, Barnes L, Napoli N J, Thibodeaux J 2019 The Restorative Health Benefits of a Tactical
Urban Intervention: An Urban Waterfront Study Frontiers in Built Environment 14
https://doi.org/10.3389/fbuil.2019.00071
[6] Moreno, C, Allam, Z, Chabaud, D, Gall, C, Pratlong, F 2021 Introducing the “15-Minute City”:
Sustainability, Resilience and Place Identity in Future Post-Pandemic Cities Smart Cities 4 93-
111 https://doi.org/10.3390/smartcities4010006
[7] Mueller N et al, 2019 Changing the urban design of cities for health: The superblock model
Environmental International 134 https://doi.org/10.1016/j.envint.2019.105132
[8] Barcelona Superblocks Program https://ajuntament.barcelona.cat/ecologiaurbana/en/bodies-
involved/citizen-participation/superblocks
[9] Narboni R, 2015 Recent evolutions in lighting master planning Proceedings of 2015 PLDC 5th
Global Lighting Design Convention
[10] Brainard G C, Hanifin J P, Greeson, J M, Byrne B, Glickman G, Gerner E, Rollag M D 2001
Action spectrum for melatonin regulation in humans: evidence for a novel circadian
photoreceptor Journal of Neuroscience 21 6405–6412 https://doi.org/10.1523/JNEUROSCI.21-16-
06405.2001
[11] Brown T M et al, 2022 Recommendations for daytime, evening, and nighttime indoor light
exposure to best support physiology, sleep, and wakefulness in healthy adults PLoS Biology
20 3 https://doi.org/10.1371/journal.pbio.3001571

10. [12] Nadybal S M, Collins T W, Grineski S E 2020 Light pollution inequities in the continental United
States: A distributive environmental justice analysis Environmental research 189
https://doi.org/10.1016/j.envres.2020.109959
[13] Col·lectiu Punt6 2019 Urbanismo feminista. Por una transformación de los espacios de vida Virus
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