The issue of the impact of lighting on health is difficult to consider separately from factors that more significantly affect a person’s well-being: stress, level of physical activity, lifestyle. High-quality light is not capable of responding to all environmental influences, the influence of which is individual for each person and cannot be predicted.
Through lighting it is possible to improve the condition and create comfortable conditions, but this is not a magic solution to solve the variety of negative influences to which a person is exposed, as confirmed by studies of the visual and non-visual effects of lighting.

Particularly complex is the process of creating urban lighting that is comfortable for humans in an environment, where the number of influencing factors is large, and lighting systems are built on a combination of different types of lighting, which are very difficult to connect with each other – especially since each type of lighting has its own tasks and is designed by different specialists. At the same time, there is no system for a comprehensive consideration of the conditions of human perception of the environment loaded with various types of lighting and control of the obtained result of the functioning of the lighting system. Figure presents a possible division of responsibilities between the urban lighting designer (ULD), the architectural lighting designer (ALD) and the urban lighting planner (ULP), proposed by researcher Dr. Karolina M. Zielinska-Dabkowska.

In addition to creating comfortable conditions for perception, city lighting can create a sense of the cyclical nature of the day. It is important to develop scenarios for using illuminated objects for it.
Lighting scenarios can be the result of using and combining complex control systems, or they can be implemented on existing equipment – the main thing here is not so much the availability of technology as a thoughtful approach to the lighting of the city or its small fragments, understanding the peculiarities of the functioning of different types of lighting, understanding the requirements for lighting in terms of distinguishing objects in the field of view, reading contrasts and the possibility of reducing the intensity of illumination of objects after nightfall. The figure illustrates Arup Lighting’s proposed approach to looking at people’s activity in the evening.

Recently, there has been an increased demand for a reduction in the intensity of external influences: the desire to relax away from the city, to rest from the information flow to minimalism and reduction of environmental detailing. In the professional community in recent years, the following topics have been raised: light detox for sustainable cities in the 21st century, darkness design (dark sky), approaches to urban lighting design and sustainable urban development with ecological potential, paradigm shift.
Thus, in the field of lighting, the issues of revising familiar approaches are relevant. To reduce the intensity of the impact of lighting at night, we need elaborated scenarios of its functioning.

Now, the potential of using scenarios for lighting in urban environments has not been sufficiently realized: as a rule, the concept of scenario is associated with color change or content change, or with the concepts of holidays and weekdays and adding color accents of the weekend. But the scenario is not only about spectacular change and color shimmers.
A scenario can be the result of analyzing existing lighting systems, selecting a hierarchy of objects and the nature of their use in the evening and night: establishing lighting priorities that may change over time within a single day.
Against the backdrop of increasing interest in the notion of light detox, scenarios can be evening and night. The introduction of the night scenario is related to a more respectful attitude towards biodiversity and to consider the need for people to rest at night and the need to save energy at the city level. The figure shows an example of lighting intensity control depending on the time of day and space utilization pattern of Xixian city, developed by Arup Lighting.

The lighting palette of the evening scenario for the city can be flexible to changing environmental conditions: reflect the change of seasons, consider the light climate, the time of darkness and change the intensity of artificial lighting depending on the dynamics and rate of change of natural lighting conditions. The very transition from dusk to total darkness differs in duration from geographical location and can be customized for the city by developing a scenario of evening lighting changes applicable to the geographical location in question. The figure shows the length of daylight hours at different latitudes for different seasons © Arup Lighting.

The solution of an evening scenario may depend on:
– geographical location of the city
– light climate
– the season and its influence on the duration of darkness
– the duration of twilight depending on the season

The development of a night scenario may depend on:
– prioritization of illuminated objects in terms of their importance in the city structure
– reduction of the intensity of use of urban infrastructure
– hierarchy of architectural objects

Unfortunately, the request to work out a night lighting scenario that involves reducing the luminance intensity of devices is not common. The positioning of cities is mainly focused on increasing brightness, on increasing the number of illuminated objects – and it is assumed that this is good by default. In such positioning, the interests of people who do not want to artificially prolong the night life, who care about nature, are not represented in any way. At the same time, it is possible to develop scenarios for the functioning of lighting according to the nature of the use of spaces even after the implementation of lighting projects by carefully analyzing the activity of the users of the environment.

So, to form a comfortable lighting of the urban environment it is necessary to consider the following lighting parameters:
– lighting intensity depending on the functional use of spaces (levels of brightness and illuminance)
– character of brightness distribution in space (contrast ratios between different surfaces, the feeling of saturation of spaces with illumination).
– glare of lighting fixtures
– spectral composition of light sources
– color of illumination.

To further development of lighting scenarios, it is necessary to:
– analyzing the activity of people and the opening hours of various establishments – assessing the use of the urban environment during the evening hours
– analyze the requirements for lighting levels after nighttime intensity reduction.
– analyze architectural lighting objects that do not require lighting after 12 a.m. in the context of the city and turn them off.