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Lighting : LIGHTING Apr-May 2018
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26 LIGHTING MAGAZINE | April/May 2018 It is surprising that the window has remained in office buildings, since it has disappeared from factories and shopping malls. I suspect that it remains as an architectural element; how do you treat a façade without windows? It also remains for the views that can be a valuable leasing asset in prime locations. However, windows are very expensive (compared with walls) and there are the problems of solar heat gain and glare. The solar heat gain is handled by air conditioning, since energy is still relatively inexpensive compared with the rental income from the floor area that might be lost due to sun-shading, etc. It could be argued that architects have forgotten, in a period of only 50 years, how to design with the sun and sky; relying upon technology, rather than appropriate design, to make buildings work. Maybe that is a little unfair but there are very few examples of appropriate daylighting design. It is all the more surprising, since the “design” of windows remains in the domain of the architect and most architecture schools continue to teach rudimentary daylighting design methods. However, the reality is that architects have very little control over the design of buildings. Economic imperatives determine almost everything and the most influential people seem to be the property agents who advise on rental returns. A lot of research has been done on improving the performance of windows but much of this assumes initial “bad” design with add-on technology to improve performance. THE FUTURE FOR DAYLIGHTING BUILDINGS While ever energy remains cheap compared with the other costs of running a business (ie, compared with the cost of the people) legislative measures are needed to require that certain performance criteria are met. However, with regard to lighting design, there needs to be a revolution similar to that which produced the framed building; a quantum leap is needed – not the current methods of trying to make “bad design” work. Lighting designers need to be true lighting designers – not just electric lighting designers. They need to know how to design with all sources, especially skylight and sunlight. Significantly, AS/NZS 1680 anticipated this in 1990; it is the Standard on Interior Lighting not Interior Electric Lighting and an examination of the Standard shows that daylight is discussed in the section on light sources and windows are discussed under luminaires. Lighting systems are assumed be electric light and/or daylight. Unfortunately, the design professions, particularly, lighting designers have lagged behind the Standard by at least 28 years. The lighting manufacturing industry should be producing luminaires that make use of daylight, particularly, sunlight. A little imagination should see the viability of luminaires that make use of the 100lmW-1 of sunlight and the 150lmW-1 of skylight efficacies. It is easy to minimise the infra-red externally, so the system efficacy should be high. It would be easy to incorporate electric lighting into these systems. With high volume production, the prices should be similar to current, quality electric-only luminaires. The reason for this suggestion is that it is unlikely that buildings will ever return to the generous proportions needed for windows to work as light sources in modern commercial buildings. The rooflight should have a future in low-rise buildings if there are legislative measures to require industrial buildings and warehouses to be more energy- efficient. Clever design should narrow the gap between the portal frame and more sophisticated rooflighting systems. An industry needs to emerge to create these products; but why shouldn’t that be a logical extension of luminaire manufacturing. FINALLY While realising that that modern working environments face many challenges both in terms of their physical design and the design of work tasks themselves, electric lighting has been a great enabler in the exploitation of space in buildings by minimising dependence upon daylight. It is time to revisit the dependence, now, on electric lighting by seriously exploring how greater use can be made of daylight. Rather than the lighting industry fearing daylight, it should embrace it, creating demand for new daylighting technologies and products; daylight is, on average, usefully available for less than 12 hours per day. If the lighting world is truly seeking human-centric lighting, don’t ignore the obvious: daylight. A little imagination should see the viability of luminaires that make use of the 100lmW-1 of sunlight and the 150lmW-1 of skylight efficacies. It is easy to minimise the infra-red externally, so the system efficacy should be high. It would be easy to incorporate electric lighting into these systems. LIGHTING AUSTRALIA INSIDE AND OUT 1300 236 467
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