Lighting of Lviv: A Healthy and Comfortable Environment

admin-luminal

27 April, 2026

“Five seconds” — that’s how long, according to the U.S. National Library of Medicine, our eyes — more precisely, the cone cells — need to adapt from a bright environment to a darker one and begin to distinguish objects. Of course, this is an average, as many factors influence the duration.

It may seem like a minor detail. But behind it lies a question of safety — one of the most critical functions of nighttime lighting, and one that is often overlooked. For example, when a car moves from a well-lit section of road into a darker one, the driver simply does not see (more accurately, does not have time to see) a pedestrian in the blind zone during those same five seconds. Every abrupt transition between light and darkness triggers a new cycle of visual adaptation.

Hence the critical importance of lighting uniformity in movement zones. When a person is sitting in a café or relaxing in a park, contrast between bright and dim areas is entirely acceptable — even pleasant. But as soon as movement begins, especially vehicular, uneven lighting becomes a hazard. The eyes simply cannot adapt quickly enough, and dark gaps between luminaires create blind zones where a pedestrian or obstacle may go unnoticed. This is why setting the right priorities for different urban zones is not only an aesthetic matter, but прежде всього a question of safety.

Working with international standards — particularly the American LEED and the British BREEAM — LUMINAL has become familiar with the BUG rating system. These frameworks regulate not only how much light is required, but also what kind of light it should be in terms of its impact on both the environment and people.

BUG is an acronym for three parameters that describe the “harmfulness” of any outdoor luminaire. Backlight refers to light emitted in the reverse direction, outside the intended lighting zone — where it should not go at all. Uplight is direct light emitted upward into the sky — the primary contributor to light pollution. Glare is the visual discomfort a person experiences when looking toward a light source.

The higher the proportion of useful light relative to these three parasitic components, the better the rating. Reputable manufacturers have long included BUG ratings in their luminaire specifications for different use scenarios. It is a clear, measurable metric that can — and should — be actively used in design.

Glare deserves particular attention, yet in practice it is often overlooked. In Europe, for instance, a road cannot be certified if the measured glare index exceeds the permissible limit. LUMINAL calculates this parameter for every project at the design stage — and if it is too high in a given area, alternative optics or mounting strategies are selected. To reduce backlight, lens shields or various visor elements are used.

Human-Centric Lighting: Markers That Shape Our State

Over the past five to seven years, the lighting industry has undergone a genuine paradigm shift. Science has finally confirmed what had long been intuitively understood: light has a profound impact on the human circadian rhythm, levels of activity, ability to concentrate, and the quality of sleep and rest. Most of this research has been conducted in the field of interior lighting — offices, hospitals, schools. But what of it can be translated into the urban environment?

It is useful to think about urban lighting through the concept of “markers” — signals that light sends to our bodies, and which can be deliberately used in designing city spaces.

The first marker is the level of activity. Color temperature directly influences how stimulated or relaxed a person feels in a given space. Cooler, whiter light activates and energizes. Warmer, more amber-toned light calms and prepares the body for rest. This means that by adjusting color temperature across different urban zones, one can communicate — without words — the character of a place: here is a lively commercial street, here a quiet park for walking, and here a recreational area.

The second marker is the circadian cycle. The human body evolved over millions of years under natural light conditions: daylight, sunset, and then firelight. All our biological processes — including melatonin production — are attuned to this rhythm. That is why warm, “fire-like” light in the evening is not merely an aesthetic choice; it is a physiological signal that the day is ending and the body should shift into recovery mode.

At the same time, color temperature alone is not a sufficiently precise tool. A far more informative parameter is the light spectrum — the full distribution of wavelengths emitted by a source. This is why, in design, it is important to consider not only the numerical value in kelvins, but the actual spectral composition of the light.

The third marker is pedestrian crossing safety through color. There is a widespread — and generally sound — idea: to distinguish pedestrian crossings with a different color temperature, so that drivers can recognize the marker from a distance and anticipate the presence of pedestrians. The logic is solid.

In practice, however, this approach is often poorly executed — either the luminaire causes glare because no one accounted for the glare index, or the difference between the color temperature of the crossing and the roadway is so minimal that no real marker is perceived. In such cases, the entire concept loses its effectiveness.

The fourth marker is focus and concentration. At night, human vision operates in a so-called mesopic mode — intermediate between daytime (photopic) and nighttime (scotopic) vision. In this state, color rendering tends to correlate with color temperature: warmer light generally provides lower color rendering, allowing the brain — less engaged in processing color — to rest more.

But is this always beneficial? In areas where attention and alertness are critical, higher color rendering may be necessary. In places intended for rest, the opposite may be true. Where exactly to draw this boundary in the urban environment is a question that should become part of a serious discussion in the development of a lighting master plan.

The Ecology of Light

The impact of urban lighting extends beyond humans — it affects all living organisms, the entire urban biome, each with its own circadian rhythm.

A particularly telling example is bats. A single bat can consume up to three thousand insects per night, making them one of the key regulators of pest populations in urban ecosystems. However, artificial lighting disrupts their natural routes and alters their activity patterns, as they are nocturnal animals that rely on darkness for orientation.

This issue has already reached the level of municipal decision-making. On the outskirts of Copenhagen, one district has switched to lighting exclusively in the red spectrum — precisely because bats are least sensitive to it. For humans, such lighting is also acceptable: red “contour” light does not strain the visual system and still provides sufficient spatial orientation. Milan has gone even further — conducting dedicated research on bat migration to understand which lighting configurations have the least impact on them.

In practice, there are three levels of a bat-friendly approach. The most effective is the red spectrum, as implemented in Copenhagen. A compromise solution is amber light: lenses or LEDs that filter out the blue spectrum and produce a warm yellow-orange glow. The third option is a candle-like temperature of 1800K, which mimics the emission of sodium lamps.

This leads to a somewhat unexpected conclusion. Many cities today are rethinking sodium lighting — the very type we have long considered outdated. In terms of spectral composition, impact on biological rhythms, and ecological footprint, it is in fact highly effective. Its main drawbacks are practical: the need for lamp replacement and higher energy consumption. However, Nichia has recently introduced a 1800K LED that essentially replicates the benefits of sodium lighting while offering all the advantages of modern LEDs — longevity, energy efficiency, and dimming capability.

Two LUMINAL projects demonstrate how these approaches work in practice.

The first is Lviv Tech City — a residential complex designed by the Warsaw-based bureau UDP, with LUMINAL responsible for facade lighting and site illumination in accordance with LEED standards. The entire lighting system operates strictly top-down — with no uplight whatsoever. The contrast between illuminated and dark areas at the pedestrian level does not exceed one meter, complying with established norms. The spectrum is enriched with red wavelengths (high R9 value), making the lighting both comfortable for humans and environmentally responsible.

The second is a cottage community where LUMINAL was invited to redesign an already installed lighting system. A custom bollard luminaire was developed with an inclined reflective surface: the light is bounced off this surface and directed downward, while the source itself remains completely hidden from direct view — no uplight, yet a wide and uniform distribution of light.

This fixture was later included on the Dark Sky International website in the list of Approved Luminaires. A simple конструктивне рішення that fully aligns with dark-sky principles.

How to Apply This to Lviv’s Lighting Master Plan

For those involved in developing the city’s lighting master plan, the sequence of actions should be as follows. First — define the markers: where activity is needed, where calmness should prevail, and how the city transitions throughout the day. Next comes zoning, taking into account illuminance levels (lux), uniformity, and the absence of glare and visual discomfort. Only after these priorities are clearly established should one move on to systematizing specific technical solutions. In this order — not the other way around.

An aerial photograph of Lviv taken from the Citadel during a test lighting setup reveals a telling picture: harsh contrasts on facades, over-illumination, and a chaotic mix of color temperatures. But this is not a reason for discouragement — rather, it is further evidence that the work ahead is both necessary and meaningful.