Daylighting is Lighting

In 2004, LightFair initiated the Daylighting Institute, a two day intense program featuring top researchers, educators, and designers, and the Daylighting Pavilion, a section of the show floor devoted to skylights, shading systems, and other products unique to the rapidly growing field of daylighting. Both are part of a series of dramatic changes and enhancements of the LightFair Exhibition and Conference, adapting to the dynamics of the economy and the practice of lighting designers, engineers, architects and other building professionals.

At first, the thought of daylighting being part of a lighting exhibition may seem odd. After all, throughout history, daylighting has been seen as the purview of the architect, who artistically and intuitively has designed windows, clerestories and skylights to be a very significant part of the building's skin. Indeed, during the late 20th Century, the glass curtain wall and galleria glass roof became ubiquitous architectural designs, defining modernism. Given this apparent ownership of the medium, it would seem that daylighting belongs in a purely architectural program.

The problem is, architecture as a profession has failed to make daylighting sufficiently important to draw much attention. As the joke goes, in the course of their careers architects learn less and less about more and more until when they die, they know nothing about everything (the engineer is the opposite). With the rapidly expanding issues of architectural practice and increasing regulation and demands for attention to sustainability and other issues, daylighting is just one of a thousand issues and has largely been lost in the shuffle. In North America, for example, the last major conference in daylighting prior to LightFair was in 1986.

But there is also another issue. Designed without requisite care, daylight can be dangerous stuff. It can cause unwanted solar heat gain, significant on-peak power demand, localised thermal discomfort, disability and discomfort glare, and photodegradation. Many of the impacts of daylight are beyond the considerations of day-to-day architecture. The average practicing architect is no better equipped to evaluate, say, the glare of a daylighting scheme than he or she is at evaluating the glare of electric lighting - which, by the way, I hope I don't have to explain in this lighting journal.

But perhaps the greatest revelation of all is to grasp the powerful similarity between daylighting and electric lighting. Once one gets past the risk of stepping into the architect's territory, the parallels amount rapidly. Consider the following:

• Lighting calculations - and especially state of the art, radiosity and ray-tracing programs - provide high accuracy predictions of daylighting performance and illustrate renderings of daylighting effects. Once adjusted to the issues of a varying source, it is possible to set maximum and minimum daylighting criteria so that designs can be compared and evaluated much more easily than using historic architectural methods like artificial sky and heliodon measurements of scale models.
• Key principles of fixture design - efficiency, candlepower, shielding, and photometric distribution - are now being used by skylight manufacturers to make products that perform like good luminaires. For instance, modern tubular skylights are now using 95%+ reflectance silvered aluminum tubes to maximise tube efficiency - the same material that was originally developed for luminaire reflectors.
• Key principles of lighting design - illumination, luminance, brightness and colour - are the same as with electric lighting. For example, one selling point of the "light shelf" is to turn direct sun light into indirect lighting, turning the potential glare of a brilliant point source into softly distributed, comfortable illumination.
• Key principles of energy efficiency - minimum power density, power demand reduction and controllability - are similar and close to electric lighting, albeit with an interesting twist. Daylight is often bountiful during periods of peak electric demand - summer days in particular. With its high equivalent efficacy of at between 100 and 200 lumens-per-watt (depending on many factors including fenestration, solar orientation and weather), properly designed daylighting can provide equivalent or higher light levels than electric illumination while reducing both the lighting power and cooling loads.

Because lighting design is a multidisciplinary practice that embodies architecture as well as many other fields of specialty, making the leap into daylighting design is perfectly suited for those among us whose breadth of interest, study, experience and passion can embrace this elusive but profound source of light. Aside from providing just illumination, daylighting benefits learning, shopping, working, and a host of other societal benefits. Coupled with dark nights, daylighting is increasingly targeted as a major contributor to strengthened circadian rhythms and in the long run, dramatically improved health. So not only does daylighting present a dramatic opportunity for design, its contributions to our projects will serve living creatures in many ways better than the electric lighting systems - the design of which we've become so proficient.

Daylighting is in many ways like electric lighting design, but 25-30 years behind schedule. A quarter century ago, pioneers in electric lighting design were differentiating themselves from architects, engineers and product salesmen by embracing the medium of light separate from the more tangible elements of structure, lamp and wire. Daylight is really no different, although its variability due to astronomic and climatologic impacts adds a whole new dimension largely missing from the practice of electric lighting. As we tackle the challenge, expect to see a burst of creativity not unlike the dramatic change in electric illumination design over the last 25 years.

We should also be more prepared to have our opinions and authority challenged. The ego of architecture will not give up sole ownership of daylight easily. We will fight with engineers as technical and aesthetic issues of a design clash. We will compete with an increasingly skilled and capable sales force of daylighting product suppliers for our livelihood and the respect of a building design team. We can expect published articles and awards to be given to very bad daylighting designs as we seek to have our work acknowledged through the press. We will suffer value engineering, substitutions, cost cutting, and other practical indignities of our work. And then maybe 20 years from now, a reasonable number of new buildings will exist, that despite these obstacles to change, will have better daylighting designs than we typically encounter today.

information : www.iald.org