The old adage of measuring twice and cutting once applies just as well to design as to construction, and especially to the design of our lighted environment. Lighting can certainly be judged quantitatively, and it often needs to be, but it is also always qualitative and very subjective. The perception of brightness, the balance of light and dark, shade and shadow, and the appropriate contrast to enhance a sense of dimensionality without visual clutter, all play a role in the quality of lighting.
Sometimes numbers aren’t enough, or they don’t show the whole picture; sometimes seeing really is believing. In the case of a recent high-rise tower project, the penthouse screen wall was backlighted to create a glowing crown within the nighttime skyline. This started as a computer model to study the relative output needed, along with the general patterning of the screen wall structure. Then, during the glass selection process with the architect, a series of full-scale mockups were done on the rooftop of the existing building to evaluate the appropriate brightness.
Numerous glass samples were explored and tested, during the day and backlighted at night. Various frit patterns and interlayer films behaved differently at night, lighted from one side, than they did during the day when daylight illuminated both sides.
Care was taken to accurately simulate the structure supporting the screen wall, in order to represent realistic shadowing; however, the primary purpose of the full-scale mockups was to determine with the client the preferred brightness of the backlighted glass. There was no right answer in this case.
If the process had stopped there though, we still would have missed the mark, because brightness was only one piece of the composition. The next step went back to small-scale modeling. A 1/4”-scale physical model was constructed of one entire façade, with all of the structure and fixtures accurately represented. This allowed the overall pattern of the wall, with all of its potential shadows, to be scrutinized and explored.
The interplay of shadows from vertical and horizontal structural elements, in relation to standard fixture lengths, created a depth to the lighted wall that, at this grand scale and from normal street-level vantage points, became a positive quality that the entire design team, along with the client, preferred over a relatively uniform and flat appearance. The distinction between texture and visual clutter can be a very fine line, and neither the computer model nor the full-scale mockup really told the full story.
Sometimes the answer is quick and right in front of you, and other times, especially when perception and subjective qualities are in question, multiple methods need to be explored to make sure that the right measurement was made. A single measurement would have cut this design too short.
Photo Credits: D Sharon Pruitt (1), Lam Partners (2-5)