23 Nov The importance of lower light levels, shade, shadows and darkness in lighting – featured in EE Publishers’ Vector Magazine
New lighting technologies are about to change the way we do lighting design, how we install lighting and how we will use it.
Day is, of course, divided into daytime and night time or, put another way, light and dark. Daylight gives us energy and we can see to perform our tasks. Our bodies are structured and adapted to function in certain ways during periods of light and dark.
We are inseparable from the universe and the sky above us but sky glow caused by city lights obliterates the night sky and makes it possible to see only a handful of the brightest stars at night. The reason is that we have lost all respect and perspective judging by the way we treat our planet and the amount of light pollution we create.
I am just as guilty as most; I have designed street and sport field lighting over the years which contributed to light pollution before I became aware and more sensitive to the plight of the environment. So, I am not the accuser in this regard but rather the thought-provoker so that we can meet the future more sensitive to our surroundings.
Indoor lighting is without doubt where we see most poor lighting designs. In my opinion, these are the result of the fact that no institution exists in southern Africa where illumination engineering is taught (other than the BHA School of Lighting in Cape Town).
It has long been the practice to illuminate work places from corner to corner, with high uniformity and the same colour light as this was what the standards prescribed. On close analysis, the detail prescribed in the standards is only read where the illuminance levels are prescribed for each application type. The real important detail, including specifying the different areas within a single space which require different illuminance levels, contrast and glare are often overlooked completely. Often, the specified luminaires do not deliver the performance claimed by the supplier, which adds to the problem.
Fig. 1: Rogier van der Heide’s installation at the Rijksmuseum in Amsterdam, the Netherlands.
Lighting and the daytime economy
Few lighting designs (if any) take into account natural daylight, to harvest it effectively or know and understand what daylight autonomy and continuous daylight autonomy mean, let alone how to incorporate them into their lighting design of interiors.
Over-illumination is a cardinal sin in interior lighting and is the result of poor understandings or ignorance of the office layout or the tenant’s requirements at the time of the lighting design. Perhaps it is also due to a lack of imagination and the inability to think about new and innovative ways to approach installations.
Change the status quo
Albert Einstein famously said, “Imagination is more important than knowledge for knowledge is limited to all we now know and understand while imagination embraces the entire world and all there ever will be to know and understand.” He also said that approaching old problems from new angles “requires creative imagination and marks real advance in science.”
Lighting professionals, illumination engineers, consulting electrical engineers, architects and lighting designers owe it to their clients to know as much as possible about the subject of illumination, including all there is to know about light; the human eye; vision; lighting economics; physiology; physics; mathematics and, these days, lighting controls and the ICT environment.
Lighting and ICT
Office, commercial, industrial and other lighting will soon be powered over the Ethernet data system and will form part of the IT network. We must understand the requirements of each system so that software architects can design the software for use with the multi-faceted controls required by lighting installations. We can only concentrate on the business of lighting design once the requirements in terms of knowledge, understanding and experience have been met.
Fig. 2: Swarovski “Dream Cloud”by Rogier van der Heide.
Standards dictate specific illuminance levels on primary task areas. Areas adjacent to those areas can be around 60% of the task illumination. Pause areas in the building (where employees relax) can be 20% of the task illumination, but never less than 100 lux.
Lighting in the pause area is not likely required for safety, making these areas ideal to treat as shade areas, restful places where lighting or the relative absence of lighting is provided for the workers’ health and well-being.
There are countless other possible uses for shade and even darkness to create visual effects. Workers prefer less light in these areas. The author has seen many offices and call centres where employees remove fluorescent tubes and cover fittings to reduce the amount of light.
In most of these cases, management has either ignored the workers’ preferences or paid “experts” for their opinion. These “experts” typically simply confirm that the lighting meets the standards or the OHS Act. However, luminaires can be repositioned and light levels reduced in these installations, with excellent post-intervention results.
Few workers today do not use computers, often with their brightness levels set higher than needed to see the screen images because of the high illuminance levels in the office.
While the standards require 500 lux where computer work is involved and a regular office requires only 300 lux, even 300 lux is too high to work in comfortably on a visual display screen.
In Europe and in many new buildings with democratised lighting control (via smartphone apps), the average illuminance level preferred by the workers is between 150 and 200 lux.
The scotopic and mesopic richness of LED light must also be borne in mind when using LED light sources or luminaires. Most light sources have a degree of scotopic/mesopic richness, most to a lesser extent than LED.
Rogier van der Heide, former director of Arup Lighting and vice-president and chief design officer for Philips Lighting and the Zumtobel Group of Austria, has mastered the art of appreciating and incorporating darkness into his lighting designs. These include Amsterdam’s Het Rijksmuseum (see Fig. 1); the Beijing Olympic Stadium; the Yas Marina Hotel in Dubai; Abu Dhabi’s Sheik Zayed Bridge; the Canton Tower in Guangzhou; a Black Eyed Peas world tour; the Holland Casino in Rotterdam and the Swarovski Crystal Palace in Milan (see Fig. 2).
Fig. 3: 1950s car dealership, lighting by Richard Kelly.
Van der Heide quoted famous architect Le Corbusier in a presentation titled “Why light needs darkness”: “Light creates ambience and the feel of a place as well as the expression of the structure”.
This sums it up: we should use light and darkness in our designs.
The time has come for lighting designers to ensure that we not only provide light in a minimalistic way to meet budgetary constraints and the dictates of industry standards. It is time to use our expert knowledge to guide and influence clients and developers to budget for quality, healthy, modern and compliant lighting and the latest technology.
Well-known American architect Richard Kelly (1910 – 1977) coined the phrases, “focal glow”, “ambient luminescence” and “play of brilliants”. His work included some very impressive lighting, such as the 1950s motor car showroom installation in Fig. 3. Kelly also reasoned that “darkness is needed for the imagination and for contemplation”.
Sporting events, street lighting
There is much light pollution during sporting events due to the amount of light produced: around 39,09-million lm for 360 x1000 W LED floodlights, each requiring 1,6 A current compared to “old technology” which required about 11 A current per flood light.
Fig. 4: Gross over-illumination and light pollution from reflectance off the road surface.
High-pressure sodium street lights are still predominantly used in Cape Town, although LED is making its appearance gradually.
The amount of sky glow generated from Cobra Head luminaires is astounding. The International Dark Sky Association and the Model Lighting Ordinance (applicable overseas and hopefully soon in South Africa too) which require that streetlights produce no upward light at all and that the upward reflection off the road surface must be kept to low levels.
Street lighting standards are important because the luminaires must be suitable for the different road categories, the different road surfaces, vehicle speeds, traffic density and location of the street lights such as urban or residential.
Designers of street lighting projects have a huge responsibility to provide lighting to meet all criteria and to ensure that the correct correlated colour temperature (CCT) is used. Lighting designers should refrain from using high CCT luminaires at all costs. It is best to use 4000 K on highways and freeways where the speed limit is under 90 km/h. For all other roads, use 3000 K.
We need to take note of the initial CCT debates and pay attention to the finding of the City of Montreal and the International Ophthalmic Conference who highlighted the unsuitability for motorists of any LED light with high blue light content.
Fig. 5: Rogier van der Heide’s Louis Vuitton Worldwide installation.
Human-centric lighting studies show that the lighting colour in the workplace should be toned down to a warm white around 3000 K towards the end of the workday. Exposing motorists to high CCT on their way home could delay the onset of sleep. It could, in fact, cause sleep disruption which can contribute to heart disease, diabetes and other ailments.
Remember, you cannot simply substitute high-pressure sodium with LED of similar wattages. The result will be gross over-illumination and light pollution from reflectance off the road surface (see Fig. 4). Illumination engineers will understand that around 25 to 30% of the wattage for LED is required. Of course, luminaire design and performance will require careful analysis to be suitable for the different road types and categories.
In the past, shop windows were interesting, different and appealing. They made each shop stand out and be distinctive. Today, it is simpler to light and control every shop window identically, possibly because so many of the shops in our cities and shopping malls are owned by major holdings groups. This is a shame as shops can increase sales opportunities by being distinctive.
Exciting lighting allows the designer to use creativity, ingenuity and artistic flare with an understanding of light, shade, darkness and contrast (see Fig. 5).
BHA SCHOOL OF LIGHTING – 23 NOVEMBER 2018
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