Prague Finishes the Expert Round on Its Public Lighting Concept, With Darkness Now an Explicit Constraint

The Institute of Planning and Development has finished the first step in preparing an update to Prague's Public Lighting Concept. The step was a consultation process running over several months and built around two expert workshops, and IPR announced its completion on 1 October. The drafting of the updated concept follows.

The procedural detail matters more than it sounds. IPR initiated the process and provided the professional cover for it, but it did so on a brief from the Prague city assembly — this is a commissioned document, not an institute's own initiative. The main partner is Technologie hl. m. Prahy, the municipal company responsible for operating and developing the lighting system, and the work sits alongside the ongoing modernisation of the lighting network itself. Preparation and moderation of the participatory process was handled by Ateliér pro veřejnou debatu AVD.

Who was in the room

The list of disciplines is the substance of the announcement. The workshops drew experts in lighting technology, chronobiology, ecology, nature protection, transport, safety, architecture and urban planning, along with representatives of municipal organisations and of state administration.

Chronobiology and nature protection sitting at the same table as traffic and safety is the whole problem in miniature. One side of the room is there because artificial light at night interferes with human circadian rhythms and with animal behaviour; the other is there because streets and crossings have to be usable after dark. A lighting concept is the document that has to decide between them, street by street.

The expert workshops confirmed to us that dealing with the question of public lighting is not just about lighting technology itself, but is genuinely an interdisciplinary topic, where the requirements of safety in the streets, protection of Praguers' health, protection of nature, quality of public space and technical and economic feasibility all meet. It is important in the debate not to forget the aspects that cannot be measured by any instrument or statistic, but which fundamentally affect our feelings and our perception of the city.

— Ondřej Boháč, director of IPR Praha

The triangle, and the one parameter everybody argues about

Tomáš Jílek, chairman of the board of Technologie hl. m. Prahy, put the operator's case, and did it by naming the thing the debate usually collapses into:

The workshops showed how many different viewpoints need to be taken into account when deciding about public lighting. The voice of experts on nature and health is just as important as the experience of the people who design and operate lighting. And the economic dimension of running the lighting system is equally important, especially with regard to the energy market. Our task is to find a solution that will be safe, economical, gentle to the environment, and at the same time will meet the applicable legal regulations and technical requirements. That is why every discussion needs to keep all sides of this triangle in mind and not focus only on a single parameter, for instance the colour of the light. Every place has different needs and those need to be assessed professionally. We want to limit unnecessary and disruptive light, but streets, crossings and other public spaces have to serve people safely after dark too.

— Tomáš Jílek, chairman of the board, Technologie hl. m. Prahy

Colour temperature is the parameter that has carried most of the public argument about LED conversion in cities, and Jílek is explicitly declining to let it stand in for the rest. Read together with Boháč's point about what no instrument measures, the two quotes are the same move from two directions: both are warning against a concept written to a single number.

IPR states the aim as finding agreement on safe and functional lighting while minimising the negative effects that artificial light inevitably brings. That phrasing — inevitably — concedes the trade-off rather than designing it away, which is a more honest starting position than lighting policy usually takes.

What is not yet known

The announcement records that a structured expert debate has opened and that technical, environmental and social impacts were all raised in it. It does not say when the updated concept will be published, what it will cover, or whether it will bind anyone. Those are the questions the drafting stage answers, and none of them is settled by a workshop.