For a new 22-bed behavioral-health unit on two floors of an existing hospital, designers from ZGF wanted to imbue the two central gathering areas—which have no access to daylight—with a natural sense of the passage of time. In order to accomplish this, they developed an illumination scheme based on circadian-rhythm research conducted by the Lighting Research Center at Rensselaer Polytechnic Institute. The lighting subtly changes, with a bright, cool light in the morning that gradually becomes warmer over the course of the day. The aim was not only to provide a comfortable environment, but also physiological benefits for patients who are sometimes admitted for weeks at a time and spend most of their waking hours in these spaces, explains Ed Clark, a ZGF sustainable strategist. To create an installation that would reinforce patients’ natural wake-sleep cycles, they specified high-CRI tunable-white LED downlights from USAI. And to facilitate the desired modifications in color temperature and intensity, they paired the downlights with a 0–10 volt dimming system. For a cove surrounding the main raised area of the ceiling, they chose double-diode linear LEDs (one orange and the other blue) and a separate DMX control system. When first installed, the fades between colors of the downlights were too abrupt, making the environment “like a disco,” jokes Clark. But after reprogramming, the transitions are now gradual and nearly imperceptible, he says.

Next case study: Wimbledon Centre Court by Populous and ME Engineers