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4: AVOID GLARE One of the major lighting problems in libraries is glare. Glare comes in two varieties. Direct glare blinds us. When the sun or lights shine straight in our eyes, it's almost impossible to see anything, and it's certainly unpleasant to try to work. Indirect glare is the other type. It consists of images of bright lights reflecting off shiny surfaces, such as book paper (another in the long list of good reasons not to accept donations of The National Geographic) or computer screens. The technical name for indirect glare is "veiling reflectance," since the reflected images of concentrated light sources veil the information beneath shiny surfaces. Much of the glare we experience is due to unfortunate lighting choices. Avoiding glare is not extraordinarily difficult, but you have to bear the problem in mind while your library is being designed. Avoid direct lighting As far as we are concerned, the most satisfactory way to light a library is by bouncing the light off the ceiling. The closer we come to a totally evenly illuminated ceiling, the more we reduce both direct and indirect glare. With scattered downlight lights of any type, you will find areas where it's almost impossible to read the spine labels on high shelves. The fronts of the books will be in darkness, and when you try to look at them you'll find that you're staring straight into a light fixture. Avoid dark ceilings Dark ceilings make the entire effect of direct lighting even worse. Doing this kind of thing on purpose in a library is genuinely sinful. Sometimes, however, we have historic dark ceilings we can't paint white. We saw one example of an arts and crafts era library with an historic dark cork ceiling with stenciling. In this case, the architect fell back on very traditional lighting—dim chandeliers for navigation, plus table and shelf lights for reading. It works well, and no bright lights shine directly in your face. Prefer north light Direct sunlight can cause serious problems in libraries. It blinds readers. It fades books. It creates terrible problems with computer screens. And the contrast in brightness between areas struck by daylight and areas with artificial light can make perfectly adequate artificial light seem far too dim. Yet everyone loves daylight—and to be able to see out. When we visit libraries with windowless rooms, almost the first thing we hear from the staff is how much they want windows. One way to avoid glare from daylight is to use as much north light as possible. Artists love north light because it is almost never direct—especially in the northern parts of the US. The light from north windows is almost always pleasant for reading—although even north light can produce glare on computer screens. South light can be controlled in summer with overhangs over the windows. In winter, the library will need other ways to control the light, although some users like sitting in the direct south sun on winter days. East light needs morning shading in the summer. West light is almost always evil. If you have western windows, you will need effective ways to block the light in the afternoon. Due to the nature of natural light, libraries with east-west orientations usually work better than those with north-south orientations, because they provide the greatest amount of north light and the least west light. When you are selecting a site, remember that one that permits a major north window wall will lead to the best natural lighting and the most pleasant interior. In practice, this usually means a south entrance. Windows that face any direction except north will usually need shading of some kind, even with modern types of glass. If you want windows with round or pointed tops, plan in advance how you will fit shades to them. Use clearstories rather than skylights By and large, architects like skylights much more than librarians do. In libraries, skylights cause all sorts of problems. They are too bright by day and too dark by night. Service desks or reading areas located under skylights will need supplementary artificial lighting, and because a window acts like a black surface at night, the lighting is likely to be direct. Sunlight through skylights can blind readers. It can also make it impossible to use computers when the sun falls on them directly, and annoying when images of the skylights are reflected on the front of computer screens. In addition, most skylights leak. If you want the look of a skylight, particularly in the middle of a large space where windows are far away, consider an artificial skylight. But ask your designer to explain in detail how lamps will be replaced. If you need natural light in the middle of a building, a much better approach is a clearstory—a vertical window set into the roof. It brings in a lot of light, but no direct glare. Clearstories are particularly effective when they face north. Shade windows that face intense sun Windows that face direct sun need to be shaded. Special films and types of glass help cope with direct sun—but they don't help enough. The easiest way to keep sun off glass is through the design of the building. One way is by providing overhangs that shade the windows during the proper seasons. Another standard way is using any of a variety of blinds. A number of translucent blinds are available that control glare without blacking out windows. For buildings with suitable architecture, another way to control glare is by awnings. These are particularly useful on east and west windows that need shading during the summer more than during the winter. Unlike internal blinds, awnings prevent the sun from striking the glass and warming up the blinds inside the building. The result is improved saving in energy. Avoid problem surfaces Another way to reduce glare is to avoid troublesome surfaces. Avoid shiny surfaces wherever possible, particularly horizontal ones such as glass table or counter tops. Almost all shiny surfaces have annoying reflections. It is particularly difficult to see anything beneath a horizontal glass surface. Both white and black working surfaces cause eyestrain. White surfaces reflect too much light and blind readers and workers. Black surfaces provide too much contrast between books or other work and the underlying surfaces.
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