In an office fit out that we are working on for the past month, we came across the challenge of lighting an atrium. Lighting double and triple height spaces is always a challenge, trying to do so, achieving the uniformity and UGR levels required for an office space demanded a bit more research.
We first looked at solutions been done previously, with suspending an aluminum profile from the ceiling being the first that came to mind. This is a great solution (see great example by DHA designs in Victoria and Albert museum of childhood), nevertheless the atrium we are looking at, is not as vast and a profile would have an unwanted visual impact.
The next solution we investigated was mounting spotlights on high level to light the task area. This ensures minimal visual impact while on the other hand, with LED technology it still is energy efficient. The two major disadvantages are the fact that we were directing light solely on the task area, making the rest of the atrium feel dark, quite the contrary of its initial purpose and the commissioning time, which would increase significantly. While the solution worked on our computer based calculations, it would be practically impossible to achieve the uniformity levels required in real life.
So with all this in mind, I started thinking a bit out of the box. We liked the mounting positions on high level (there is easy access for maintenance from the upper level) as they ensure minimal visual impact, but we were after an asymmetrical light distribution, similar to street lights. I started looking at façade and exterior rated luminaires and surface mounted architectural fittings. The fitting that worked for us, was the Pantrac by Erco. The Pantrac is designed to highlight ceilings, not exactly our application where we are looking in lighting downwards, yet its asymmetrical distribution is ideal for what we wanted the fitting to do. It is providing an even distribution on the task area, glare free (UGR<19 for all areas except for people standing on the edge of the upper level balcony where it is 21) and also illuminates the vertical walls making the space feel bright and spacious.