TECHNIQUES 9: The Skylight
Mindseye director Doug James talks to us about the oldest lighting technique in history and how it can achieve two very different effects.
“Of all the techniques we’ve looked at in this series, this one has by far the longest pedigree,” says Mindseye’s Doug James of the skylight. “You can trace it back to Ancient Rome and beyond. Even the Egyptians used it when building the pyramids.”
It’s little surprise this technique has such a history, being the most effective way to get a decent amount of daylight into an otherwise enclosed space. In a modern context, of course, the skylight is not just about letting daylight in, but controlling the level of light and utilising it to suit the space.
“Whereas other techniques are about integrating lighting or controlling the visual landscape, this one really gives you a chance to influence the mood of a space,” explains James. So the treatment of the skylight is very much dependent on how a building is being used. Galleries, like White Cube in Mason’s Yard and in Hoxton Square, are likely to want a uniform light that not only stays constant throughout the space but also throughout the day.
“Time is the fourth dimension in this case,” starts James. “At White cube in Hoxton Square, the architect wanted the light to be as monotone as possible. We had to provide complete control over the light levels so that it always remained the same.”
Mindseye achieved this by installing dimmable T5 fluorescents on two separate circuits: cool ‘daylight’ on one and a warmer white light on the other controlled via dimmers and sensors. The key to creating artificial daylight is to blend the two colour temperatures appropriately. During the day, cool white light can be used to supplement the natural light – especially if it’s dull outside. Then in the evening, the switch can be made to a warmer white light.
“The transition should take place over about an hour so it’s practically unnoticeable,” adds James, and this is exactly the effect achieved on White Cube’s opening night. “We had designed the system to manage a seamless transition between natural and artificial light. The gallery opened at 6pm when there was still daylight outside, and as the night wore on, the light inside the gallery stayed the same.
“By the time the guests left at 9pm, they were all shocked to find it was dark outside – none of them had realised that day had turned into night.”
While some skylights are used to supplement daylight, others can create two very different effects depending on the time of day or night. At Young House, designed by Mike Tonkin, the architect panelled over three windows that looked out on to a neighbouring wall. “He wanted to keep the natural light, but the view just didn’t suit the room’s interior,” says James. The panels let in natural light during the day, and at night are illuminated from the bottom edge rather than evoking a natural sense of daylight.
“There was no attempt at a uniform flat light – the panels are used as a feature instead,” says James of the project.
As always, there are caveats. Using clear glass in a skylight can cause problems because the lighting equipment is harder to conceal. If reflections are an issue, it will obviously make it harder to introduce an artificial light source.
However it can be done: “Lighting can be concealed or integrated into the vertical surfaces of the skylight as long as the solution is tidy enough,” says James. “In the past, we’ve run linear fittings around the edges or perimeter. But you’d need a flushed linear fitting with a really good quality diffuser to give an even fl at line of light around all four sides.”
Study the view
Even with a panel to conceal the equipment, it’s important to consider how a skylight looks from the outside in. “Always consider what can and can’t be seen,” advises James. “If the room is overlooked from above, what will people be able to see?”
An obvious but crucial aspect is maintenance. Extra care will be needed if a skylight is at the top of a stairwell, and diffuser panels need to be removable in order to access the equipment behind.
“This might determine what type of product you use,” says James. “If you want to avoid having to access the lamps for maintenance, then LED or the new super-long life T5s would work best.”