Street lighting and light pollution.

That is, how do we illuminate spaces to ensure traffic safety while protecting the environment, health and privacy of residents?

Road lighting enables safe navigation in traffic areas - it allows the terrain or road geometry to be correctly identified. It increases the comfort of residents, drivers and cyclists in built-up areas. However, it is important that the lamps do not pollute the environment or have a negative impact on users. Find out what the ULOR is and how lighting affects our health and well-being.

Traffic lights can boast a long and colourful history. Unfortunately, their impact on the environment over the years has caused enormous damage in terms of both human health, wildlife and vegetation. Improperly made lighting, especially using inefficient technologies and equipment, can cause undesirable glare and light pollution. Today, innovative solutions are appearing on the market that offset the risks, such as Lena Lighting's highly energy-efficient and environmentally neutral road luminaires, which are compatible with intelligent control systems.

History of road lighting

As recently as 40 years ago, mercury vapour lamps were used in road lighting. These were characterised by mediocre luminous characteristics and poor colour rendering. They contained high levels of environmentally harmful mercury. This type of lamp emitted a neutral white light, but its spectral distribution meant that it reflected shades of green and blue, with almost no red, which the human eye perceived as poor quality - it did not reflect the colour of the skin and caused discomfort.

Initially, mercury-source luminaires had no shades, their optics were inefficient and thus did not provide adequate light direction to the road. They were installed on overhead line power poles, which were usually too low and located too far from the edge of the road. They began to be mounted on booms with significant angles to the horizontal, in the hope that they would direct the light mainly onto the road. However, these solutions proved to be ineffective, as most of the light was lost and did not end up in the desired space, but in its surroundings: the facade of buildings, greenery and the sky, causing effects known as light pollution.

Sodium lighting

Inefficient mercury systems were used until the 1980s. It was then that a revolution of sorts took place. The now well-known luminaires with sodium sources began to be used. They were characterised by significantly greater efficiency, longevity, luminous intensity and, above all, improved the subjective perception of the eye. Unfortunately, they still contained harmful mercury and the light emitted did not reflect colour at all. Worst of all, prolonged exposure to the light increased the users' feelings of fatigue and drowsiness, negatively affecting melatonin levels in the brain.

Sodium luminaires, unlike mercury vapour luminaires, have more efficient systems and convex shades that emit light over a much wider area - including, unfortunately, to the sides and upwards. This causes a light-littering effect, in addition to the phenomenon of glare. At the commonly used tilt, sodium vapour luminaires can dazzle and illuminate the facades of buildings, causing light to penetrate through windows into dwellings. The biggest problems in this regard are generated by sodium park lighting, which uses milky, diffusing diffusers instead of a reflector system.

Mercury vapour and sodium vapour lamps emit UV radiation which is harmful to the skin and contributes to many serious illnesses. It also generates large amounts of heat, consuming large amounts of energy, which has a direct impact on global climate warming. Light reflecting off the road surface and its surroundings - especially bright buildings - ends up in the clouds, causing a phenomenon known as glow.

Luminous glow

The problem of light glare is widespread throughout the world. The phenomenon appears over illuminated areas, increasing in large urban areas. It is estimated that nearly 70% of the glow in small and medium-sized towns and cities is generated by street lighting infrastructure. It has a markedly negative effect on the functioning of living organisms, disrupting the normal cycle of life and sleep, leading to sleep difficulties, insomnia problems and the development of civilisation diseases. An illuminated sky deprived of natural darkness also hinders work in the fields of aviation, astronomy and (due to the light is an electromagnetic wave) causes connectivity and communication problems - including between Earth and satellites.

For more than a decade, LED technology has been gradually introduced in road lighting, as in other lighting markets. It does not generate large amounts of heat into the atmosphere and has no harmful mercury. It also allows harmful UV emissions to be nullified to zero. Finally, compared to existing solutions, they provide lighting with a high quality of light and colour rendering.

How to prevent light pollution using modern lighting?

Today, virtually all newly built and retrofitted lighting installations are based on modern LED systems. Road luminaires of this type require significantly less electricity to produce high-quality light compared to older technologies. They are also characterised by great longevity and low loss of light performance over time.

Modern LED technology is based on the use of a large number of microdiodes. By using appropriate optics - especially lenses - the diodes make it possible to eliminate the effect of light clutter, ensuring that only the desired space is illuminated. With the right lighting, the right luminaire design and positioning, it is possible to eliminate sky lighting altogether. An important parameter to consider when selecting luminaires is the ULOR factor, which is responsible for the proportion of light emitted into the upper half-space.

What is ULOR and how do you get a ratio of 0.00%?

ULOR is a percentage value showing the percentage of light sent into the upper hemisphere, and therefore into the sky, when the luminaire is horizontally aligned to the ground (with no tilt). The aim is for this value to be zero, meaning that 100% of the light produced should go into the lower hemisphere without directly illuminating the sky. This also has the effect of protecting against uncontrolled illumination of building facades and light penetration into dwellings.

In order to achieve ULOR of 0.00% and furthermore to reduce glare as much as possible, it is necessary to design luminaires appropriately and to avoid significant tilt (it is assumed that the maximum tilt of road lighting relative to the horizontal should not exceed 15°, in practice tilt above 10° is avoided). On the luminaire design side, appropriate shaping of the luminaire body or specialised optics are used to reduce ULOR and glare. Manufacturers also avoid placing luminous and reflective elements visible in the side and top view - including convex and protruding shades (especially frosted, corrugated or milk).

Intelligent lighting for the times

The road lighting offered by Lena Lighting uses advanced LED technology to achieve ULOR values of 0.00%. A wide portfolio of luminaire models and families, such as Tiara LED, ensures luminous emissions that meet users' needs - without over-sizing the installation or light pollution. A myriad of luminaire choices, a full range of available wattages and state-of-the-art lighting control systems, such as ClueCity, ensure that energy consumption is minimised and allow a rapid return on investment. Thanks to intelligent control systems, it is possible, for example, to set and adjust the time interval during which the luminaires are to emit light and the level of light intensity - depending on needs and changes in traffic levels at night.

With a choice of more than 30 different optics on offer, a wide range of light colours and luminaire tilt adjustment, it is possible to provide lighting that meets all prescriptive requirements. In this way, the effect of light pollution and glare is minimised - both in newly designed and existing, retrofitted installations.

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