NOT GUILTY, M’LUD

NOT GUILTY, M’LUD

LED streetlighting often gets the blame in discussions about rising skyglow and light pollution. But, really, the finger of guilt should be being pointed at illuminated advertisements, floodlighting, overly lit buildings, façade lighting, parking lots and sports grounds

By Allan Howard

It is right and proper that we consider and look to understand and mitigate the impact of artificial light on humans as well as the environment.

From an environmental perspective there is clearly a need to reduced light pollution, obtrusive light and skyglow effects so all of us can enjoy the visual amenity and the splendour of the night sky, not forgetting the impact on fauna and flora.

From a human health point of view artificial light has always had an impact, but it has never been so much to the fore as now since the uptake of LEDs.

In considering this, we need to understand that there are wide range of artificial lighting installations that impact on the night-time exterior environmental. It is disappointing that when the topic is raised that most of the discussion and finger pointing unfairly focuses on the street lighting sector.

We see this raised from a wide range of lobbying parties time and time again in written articles and at debates.

Now, it is fair to say that street lighting installations havebeen a major contributor to skyglow, especially with low- and high-pressure sodium and other lampbased light sources linked with poor luminaire optics.

GROWING EVIDENCE BASE

This is not the case now, however. Over the years, as our understanding of light pollution has increased and especially since the advent of LED light sources, we are now seeing well-designed and managed road lighting installations with very little upward light contribution. The current standards and ILP guidance documents all support and encourage this approach.

It is not just the street lighting community stating this; it is supported by detailed research work such as that undertaken by Dr Christopher Kyba, researcher at the German Research Centre for Geoscience and others, which demonstrate that well design, installed and managed street lighting is not the greatest concern.

Dr Kyba led research to understand the contribution of well-designed and operated street lighting on the night sky and especially skyglow. Using satellites, he measured what fraction of the total light emissions were due to streetlights across the city of Tucson in Arizona.

At 01.30 every morning for ten days, the city dimmed its streetlights, increasing the percentage dimming each night.

His light-from-space experiment, published in the journal Lighting Research & Technology, showed that most of the artificial light wasted – by being sent upwards into space, rather illuminating a sign, street or building on Earth – does not actually come from streetlights [1].

Rather, it comes from other sources, such as illuminated advertisements, floodlighting installations, lit buildings, façade lighting, parking lots and sports lighting. All these types of installations are responsible for most of these light emissions.

Dr Kyba in his research advised that: ‘This is really important information for policy makers and light pollution activists.” He also went on to say that ‘this does make it more difficult to solve, because there are so many contributors. It means everyone has to get together to decide what lights need to be lit at night, and how brightly.’

FOCUS BEYOND STREETLIGHTING

It is these other exterior lighting installations lighting sport, domestic, security, industrial, commercial areas and more recently large digital media screens that therefore require the focus, as separate research by Dr Kyba has also highlighted (and see the separate breakout panels at the end for more on this).

You only have to drive along one of our motorways at night to see the detrimental impact on the night-time landscape of major distribution hubs, sports lighting, illuminated advertisements as well as security lighting installations compared to which street lighting pales into insignificance.

As Dr Kyba has commented: ‘The message is not that streetlights don’t matter, because they most certainly do. The message is that, if your goal is to reduce light pollution, it’s not sufficient to consider only streetlights.’

The architectural landscape is not helping matters. Over the years, we have seen a rise in large, glazed office blocks and in the domestic arena what we might term ‘the Kevin McCloud effect’ (named after the presenter of the TV show GrandDesigns) in the encouragement of domestic premises, especially in rural areas having large, glazed areas linking the exterior with the exterior.

By day this may be fine but at night these buildings intrude, one may say trespass, into the dark landscape within which they sit.

Most do not seem to have mitigation measures to prevent internal lighting impacting on the external environment within which they sit or the exterior observer seeing into the building.

These properties are often coupled with statement exterior lighting using up/down lighters around the property, which serve little purpose apart from saying ‘here I am’.

This is a topic advised in the ILP’s GN09 domestic security light guide [2]. But, alas the main consumer retail outlets only provide lighting equipment that causes obtrusive lighting issues rather than ones that resolve it. This, I’d argue, needs to change.

Comment is being made that the advent and use of LEDs has increased the amount of lighting. This is perhaps not true; we are perhaps more aware of lighting installations than before.

In part, as white light is reflected/ refracted by water vapour/particulates in the air and, for example, in foggy or rainy conditions, we see the luminaire beam distribution.

LIMITS TO ENERGY REDUCTION?

As the UK and international governments continue to drive the adoption of more energy efficient light sources, we have seen almost the total removal of all other light sources from the market and white LED light is virtually the only source available to use.

This, I would argue, is not a good thing; there are lighting tasks that just do not fit LEDs. In the past, for a large area we would use double asymmetric projection luminaires, but there is really no good viable LED solution for this application.

Energy reduction is fine but if it removes tools that we as designers need to produce good lighting installations then I would argue it has gone too far.

Considering humans, we have always been aware of the impact of artificial light on humans, it is not a new thing, but LEDs have raised the concern and profile.

We are increasingly aware of the effect of the blue light content on humans as well as fauna and flora. Your exposure to this and any adverse effects are far greater from interior lighting installations, domestic, retail, commercial and so on rather than from street lighting. The interior light levels are far higher; you are closer to the light sources and your exposure time to the lighting installation is far greater.

When LEDs first came out the lighting industry was perhaps too happy to embrace the technology and deploy it before we fully understood it; we saw a large use of 6000K light sources, as energy efficiency was wrongly given a higher priority than ensuring the task is suitably lit.

We have seen this steadily change and 3000K is now considered best for road lighting/public lighting and we are seeing amber LEDs developed where there are wildlife concerns.

Looking back at street lighting, yes, there are many lighting installations that still need attention and change from sodium and other light sources to LED. They will be well-designed and funding is available, but it will take time to address the existing asset. Nevertheless, progress is being made.

So, I urge critics to please stop pointing the finger just at street lighting. The other ‘problem’ lighting installations of sport, domestic, security, industrial, commercial, car park lighting and advertising all need to be brought into focus. The profile and impact of such installations needs to be raised and, from there, how they can be better specified or designed and so on to ensure the task is lit but only the task and not the surrounding environment.

To conclude I’ll repeat Dr Kyba comment, as I feel it is important to reiterate it; the italics for emphasis are mine. ‘The message is not that streetlights don’t matter, because they most certainly do. The message is that if your goal is to reduce light pollution, it’s not sufficient to consider only streetlights.’

Allan Howard BEng(Hons) CEng FILP FSLL is group technical director, Lighting & Energy Solutions, at WSP

[1] Kyba C (2020). ‘Direct measurement of the contribution of street lighting to satellite observations of nighttime light emissions from urban areas’, Lighting Research & Technology, Volume 53, Issue 3, https://doi.org/10.1177/1477153520958463 [2] GN09 ‘Domestic exterior lighting: getting it right’, the ILP, 2019, https://theilp.org.uk/ publication/guidance-note-9-domestic-exterior-lighting-getting-it-right/ [3] Kyba C (2023). ‘Citizen scientists report global rapid reductions in the visibility of stars from 2011 to 2022’, Science, 19 Jan 2023, Vol 379, Issue 6629, pp. 265-268, DOI: 10.1126/science.abq7781 [4] ‘“Like a sun on Earth’: Las Vegas warning if dazzling venue built in London’s East End’, The Observer, January 2023, https://www.theguardian.com/uk-news/2023/jan/28/ msg-sphere-las-vegas-london-venue-concert-hall-sleep-light-pollution

GERMAN RESEARCH INTO SKYGLOW

Latest research has suggested there has been an alarming 60% decline over the past 18 years in the number of stars able to be viewed at night with the naked eye, writes NicPaton

The research, from the GFZ German Research Centre for Geosciences in Potsdam, correlated star visibility with changes in sky brightness. This study is separate to the research highlighted by Allan Howard is his article.

It measured readings from 51,351 individuals who used a template provided by Arizona’s National Optical-Infrared Astronomy Research Laboratory in Tucson, which is part of the US government’s National Science Foundation.

The measurements took place between January 2011 and August 2022 and revealed an annual increase of 9.6% in sky brightness. The study was published in the journal Science[3]

‘For an 18-year period (such as the duration of a human childhood), this rate of change would increase sky brightness by more than a factor of 4,’ the team stated in the paper, which was led by the centre’s Dr Christopher C M Kyba.

‘A location with 250 visible stars would see that number reduce to 100 visible stars over the same period. Because our method uses measurements made with human vision, it accounts for changes in both the radiance and spectrum of the night sky,’ they added. This would mean 60% of stars are fading from view every 18 years.

The research does point a finger of blame at LED lighting, not least as the researchers discovered that earlier measurements of sky brightness taken from satellites failed to capture the blue spectra that can veer skywards from LED lighting and which, in turn, can be particularly damaging for washing out the visibility of stars.

However, importantly, as Allan Howard also highlights, the German study ascribes blame not just to LED street lighting but to the growing amount of LED lighting now used for external advertising, commercial, architectural and domestic lighting.

The research, for example, points to the impact horizontal lighting is having on light pollution. Advertising and decorative lighting is more likely than street lighting to stretch horizontally, which can have a more harmful night-sky effect than vertically pointed streetlights, it has pointed out.

‘Light propagating toward the horizon is the largest contributor to skyglow because of its longer path length (by an order of magnitude) from ground to space at such angles. In the early evening, a large fraction of the light that escapes cities is emitted by sources other than streetlights, the study authors emphasised.

‘LIKE A SUN ON EARTH’

A planning battle is brewing in east London over concerns that a huge new concert venue will be ‘like a sun on Earth’ with massive light pollution.

According to The Observer newspaper, residents in Stratford are up in arms over the possible arrival of the MSG Sphere, which is covered by an external LED advertising display, with more than a million LEDs ‘that will show videos and adverts from dawn until late’, the paper reported [4]

A similar building is scheduled to open in Las Vegas later this year (shown above)and the company behind the project recently tested out the lighting display.

‘It’s almost like building a sun on Earth,’ a local resident told the newspaper after he saw the lights at the tip of the 111m-high spherical building being tested two miles away from his balcony.

Plans for the Stratford sphere, which is located in a much more residential setting, include a 21,500-capacity concert hall the width of the London Eye and the height of Big Ben, a nightclub, shops and restaurants.

But opposition from the residents is growing, with the proposed venue having been labelled as a ‘monstrosity’ by campaigners. The UK planning application still needs to be referred to the mayor of London, Sadiq Khan, who has the power to refuse it.

NEW PLG05 NOW AVAILABLE

With illuminated advertising, spill light from commercial units and poorly positioned external domestic lighting in the spotlight when it comes to light pollution and skyglow, it is timely that the ILP’s latest update to its guide PLG05 is now available.

PLG05 The Brightness of Illuminated Advertisements Including Digital Displays has long been recognised as the authority document when it comes to assessing illuminated advertisements by local planning authority planning officers, planning inspectors, lighting professionals and advertising industry planning professionals.

It is also specifically referenced in government guidance. It is the only authoritative lighting guidance in the UK on which those involved in the planning process can rely.

The update to the 2002 edition includes requirements for digital media displays, which have become a cause for concern with respect to their impact on the local environment as well as contribution to light pollution and skyglow.

The new guide has been developed by a panel of internationally recognised lighting experts led by Allan Howard (WSP) and consisting of professor Peter Raynham (UCL), assistant professor Karolina Zielinska-Dabkowska (Faculty of Architecture, Gdansk University of Technology) and Henk Stolk (Dutch Foundation for Illumination). It has included support from the media display industry through Outsmart, which represents approximately 40 out-of-home media owners.

Members can access the new guidance as a free digital download via the ‘MyILP’ portal. It is also available in hard-copy format, priced at £40 for members and £65 for non-members.

PARLIAMENTARY INQUIRY

The House of Lords Science and Technology Committee announced in January that it is to conduct an inquiry into the impact of artificial light and noise on human health.

Artificial light and noise are ‘pervasive’ in the modern world, the committee argued, adding that it will ‘explore the extent to which unwanted, inappropriate, or excessive artificial lighting or ambient noise may have negative impacts on human health.’

For example, it will investigate claims artificial light can disrupt sleep and circadian rhythms, which can increase the risk of heart attacks and stroke. ‘New developments, such as the introduction of LEDs, are qualitatively and quantitatively changing the levels of light and noise in the built environment,’ it has added.

The committee has therefore said it seeks to understand:

• The evidence base surrounding the impacts of artificial light and noise on human health in the UK

• The nature of the current regulatory landscape for light and noise pollution and how well these regulations are enforced

• How policy should be adjusted to minimise the impacts of artificial light and noise on human health

Because the timeframe for evidence is short (with a closing date of Friday 3 March), the ILP’s technical group formed a working party and submitted a detailed response during February. Members can however still go to: https://committees. parliament. uk/work/7256/