Light Matters

George Sexton Lighting Designer, George Sexton Associates

Hubbell & Benes, the architects of the museum’s original 1916 building, brought a sophisticated understanding of how to make the most of daylight in a large public space, and the gracious atmosphere of the building embodies that expertise. During the current renovation, the museum engaged Washington, D.C.-based lighting designers George Sexton Associates to evaluate the building and establish a means of reconciling the historic architecture with modern standards of light control. Here, Mr. Sexton illuminates the goals and process that have guided his firm’s work in Cleveland.   

Our attitude toward the 1916 building is that it was quite a wonderful experience the way it was originally designed, and we will do whatever we can to preserve that experience. But what has changed in the time since it was built is that there’s a much better understanding of the effect of light on works of art. So we’re trying to preserve the experience of the building while also protecting the works of art.

Striking this balance starts with basic investigation. In terms of protection, we look at two measures: what is the total cumulative amount of light a work of art ought to be exposed to over the course of a year, and what is the maximum brightness it should ever see. To work all of this out, we do a methodical analysis of the gallery spaces and take light-meter readings at different times of the day—10:00 a.m., 1:00 p.m., and 4:00 p.m.—and at three times of year that represent the high, low, and medium points of expected light exposure. In Cleveland those dates were June 21 (the summer solstice), December 21 (the winter solstice), and March 21 (the spring equinox). We also have lots of data gathered over the past 30 years about the number of sunny and cloudy days different places have statistically. If we’re working for a museum in Cleveland we’ll have different assumptions than when we’re working for one in Fort Worth, as I’m sure you can imagine.

Armed with these data, GSA then turns its attention to the specific works of art to be displayed in particular places. Working backwards from your conservation department’s standards for how much light different classifications of objects can take, we then work on filtering in the skylights—that’s the outer glass you see from outside the building—and the lay lights, which you see from the inside when you look up at the ceiling, to achieve the necessary light levels. This doesn’t mean that there is a constant brightness. Rather, we’re looking at an idea called reciprocity, which takes into account that there will be more daylight in the summer, but much less in the winter, and we calculate an annual total exposure. We also take into account that the artificial lights will not be on when visitors are not around, and that daylight will still shine into the galleries even when the museum is closed.

Then we figure out how much light each gallery should get based on what is in it. Very simply, objects that are inorganic are the least sensitive to light. Stone and bronze, for example, can take unlimited exposure. On the other end are things like watercolors and textiles—organic pigments on organic fibers, which are extraordinarily sensitive. The glass-enclosed spaces in Rafael Viñoly’s new building provide a wonderful opportunity to showcase certain works of art such as sculptures in full daylight. Other rooms, meanwhile, are very carefully controlled at much lower light levels.

The visitor’s experience is shaped not only by the absolute levels of brightness, but also by the change in brightness that is perceived while moving through the museum. We are reducing the overall amount of daylight that makes it to the gallery walls in the 1916 building in order to meet the museum’s conservation standards. Despite these decreased levels, though, the visitor will have an impression of more light. Some of this has been achieved by restoring the experience of the original building design—for example, by opening up skylights and lay lights around the rotunda that had been blocked off by later construction. But a lot of it has to do with paying special attention to areas of transition. As you move from one space to another, we want to make sure there are no dramatic leaps in brightness. We’ve all had the experience of walking out of a dark movie theater into the dazzling sunlight. The same thing can happen in a building, so we’ve taken care to modulate these transitions so that by the time you walk into a darker space, your eyes have already adjusted. The visitor can easily see and appreciate the work of art in conditions that also ensure the long-term safety of the object. That’s our mission in a nutshell: beautiful presentation and careful protection.   

Image

Image

Seasonal Shifts These diagrams show measured light levels in the new French neoclassical gallery (above), one of a few spaces where original skylighting has been restored. At top are the readings for the summer solstice, at the bottom for the winter solstice in December, with the spring equinox between. Red indicates brighter light. The designers are concerned not only with controlling maximum brightness, but with overall light exposure over the course of the year. These studies show how Cleveland’s dim Decembers effectively put some light exposure in the bank—a “sunny day fund” that will be drawn upon during the summer.

Cleveland Art, May/June 2008