Lighting is an integral part of the storytelling process of museums. Today, more than ever, there are a greater variety of museum types, each one distinct in its own “story,” mission, collection, and method of representation. Traditionally, museums have addressed the presentation of collections as the most important criteria in exhibition design. The visual environment surrounding these works of art and specimens usually plays an important yet supporting role, with the collections as the “stars” of the show, so to speak. In addition to these more traditional institutions, there are other types of exhibition spaces where the visual environment may be as much a part of the viewer's experience as the objects on display. New methods of presentation by architects and exhibition designers are increasing the variety of gallery-space typologies, which in turn, challenge the lighting designer to find solutions that go beyond the traditional body of museum lighting approaches and techniques.
UNDERSTANDING THE DESIGN CONCEPT
Understanding the exhibition design concept is integral to designing and integrating lighting design in museum exhibitions. Museum exhibitions sometimes focus on specific objects from a collection, while at other times, there are no objects and the story is presented through audio-visual and textual narratives. In either instance, lighting designers need to acknowledge both the content and context in order to make informed design decisions that support the overall exhibition design concept.
ISSUES TO CONSIDER1
Exhibition content and architectural context are not the only design issues facing the museum lighting designer. Conservation, facilities maintenance and flexibility are all concerns that affect lighting design decisions.
Conservation. An issue of critical importance that is unique to museum lighting is the extent of controlled light-level requirements established by conservators. Almost every museum has specific objects in their collection that are susceptible to light degradation over time. Organic materials such as wood, textiles, leather and paper, are just some of the more vulnerable items. Designing to recommended light levels, eliminating dangerous UV light and reducing exposure to lighting-related heat emissions are key considerations that need to be addressed in order to lengthen the life of the object. Conservation issues should be a priority for any lighting designer working on a museum project.
Relative Brightness. Another important component of museum lighting is the concept of relative brightness (we are concerned about relative luminance levels here—not illuminance). In order to view works on display with visual comfort, the viewer expects controlled luminance levels between the objects and the surrounding visual environment (using luminance rations). A white marble sculpture illuminated to only 5 fc may actually appear brighter (higher luminance) than an adjacent dark bronze sculpture illuminated to 15 fc simply by the change of finish. This concept is helpful when making decisions about architectural and exhibition finishes.
Flexibility. Museums often demand a certain degree of flexibility, which may assist the lighting designer in determining appropriate lighting solutions. Temporary galleries, for example, typically support all types of exhibitions including both in-house installations and traveling exhibitions and therefore require maximum flexibility.
CLINARD'S THOUGHTS: (1)The first thing that strikes me after rereading this article for the first time in almost nine years is that so many of the issues discussed are still the same today. This shouldn't be surprising since much of the article touches on topics such as visitor experience, design process, and conservation issues, which are every bit a part of today's museum environment.
CHOOSING A LIGHT SOURCE2
The selection of appropriate light sources for museums is always important. Traditionally, color quality has been and still is one of the most critical concerns for displaying art objects and specimens, but the word “quality” opens the door to philosophical questions about which types of color temperatures are appropriate. Fine art museums today, for instance, use natural light and halogen sources, separately or mixed, with success. For accent lighting, museums frequently use halogen line- and low-voltage sources because of the variety of wattages and beam spreads available on the market and because of low initial costs. For conceptual types of exhibitions, the variety of possible sources to consider is greater, including colored light that can be used to emphasize a certain exhibition design concept. As with other types of lighting projects, lamp choice should be informed by a variety of qualities and characteristics including CRI, lamp life, efficacy and lamp replacement cost.
Source selection, of course, will inform the appropriate type of lighting equipment. Adjustable fixtures, such as accent lights, should be able to accept different types of lighting media, such as glare-reducing louvers and a variety of spread lenses and color filters. All lighting fixtures for exhibition spaces must be able to accept UV filters. Additional criteria that are equally significant include aesthetics and scale, as fixtures and equipment can either support or distract from the design attitude of the space.
In museums, it is sometimes desirable to provide local, internal illumination for display cases. This type of illumination delivers an internally luminous quality and can help to reduce reflections and glare associated with the glass or acrylic vitrines or case windows. Traditional light sources for case lighting are fluorescent and halogen. These light sources are usually located above the objects on display in an enclosed light attic that must be accessible for relamping. Adequate ventilation and heat exhaustion is required for all case-lighting methods in order to prevent raising heat from entering the display case cavity. Fiber-optic lighting systems are used in display cases illumination as well. The advantage here is that the light source can be remotely located, allowing more freedom in the design of the physical display cases. Furthermore, the access panel for relamping can be located in a less conspicuous location and the individual fixtures can be adjusted without ever being touched by the lamping staff. Another advantage to fiber-optic systems is the design potential to create a miniature “stage set,” using tiny spots and floods that can be aimed anywhere within the case. The systems are also ideal for displaying light-sensitive materials because the UV light and heat associated with an internal light source (typically halogen or metal halide) are removed from the case interior.
There are also disadvantages to fiber-optic systems such as light intensity. They typically do not have enough light intensity to deal with the surrounding ambient light levels and require galleries to be fairly dark in order to be successfully integrated. They can also be more costly than fluorescent and halogen fixtures for case lighting.
Interactive exhibits, display panels and other exhibit elements for permanent and traveling exhibitions frequently incorporate internal illumination. A variety of lighting sources and fixtures is appropriate depending on the specific lighting application. Luminous or glowing elements often use fluorescent sources because of their broad distribution, long life, and low heat emission. LEDs are increasingly being used for these types of applications due to their small size, range of color, controllability, low heat and extended lamp life. They can be controlled to mix colors and even programmed to sequence custom lighting patterns and movements. White LEDs can be used for certain applications such as rear-illuminate display panels. However, at the time of this publication, the color-rendering quality of white LEDs is still not appropriate for illuminating many types of museum-quality objects on display.
Even after extensive planning, exhibitions almost always require object-adjusting and fine-tuning in the field. In temporary exhibitions, the focusing can easily make or break the overall desired lighting effect. Adequate light coverage and proper aiming angles that avoid shadows and reflected glare are just a few issues that the lighting designer must address during almost every installation.
THE MUSEUM'S PERSPECTIVE
In order to reduce lighting-related energy and maintenance problems, when appropriate, use natural light as a source—it's free and daylighting can drastically reduce energy costs over time. However, the ability to have daylighting requires higher initial costs due to the architectural impact and the additional expense of installing passive and active light control systems for light intensity and UV protection. For museums where daylighting is not an option, the lighting designer must look for opportunities to use more-efficient light sources. This is often difficult in both new construction and retrofit projects due, in part, to the viewer's expectation for light characteristics typical of halogen sources as traditionally found in most museums. But there are many opportunities nonetheless. For instance, fluorescent sources can be used for ambient light and select metal halide sources for accent lighting. When halogen sources are the only option, a dimming system can extend the lamp life many times over and also provide a time-clock control to more efficiently monitor the operational hours of exhibition scenes.
CLINARD'S THOUGHTS: (2)There have certainly been a few changes since the original article was written. Lighting technology, for example, has made what I would consider modest advancements in the museum sector. The article mentions that museums consider color quality a key issue in electric light-source selection and that halogen sources (both line- and low-voltage) were generally preferred for accent lighting. These halogen sources are still the dominant choice for accent lighting in museums today. However, other types of light sources have become more prevalent in all types of museums and galleries. Many of these changes have been driven by the need to meet new codes and standards or by interest from museums to reduce energy and maintenance costs. Manufacturers have been offering even lower wattage ceramic metal halide (CMH) lamps and fixtures that provide optics and intensity levels that are more suited to museum environments. The color quality of these CMH lamps has also improved steadily. And, just in the last few years, there are now some credible white LED accent and tracklight fixtures available on the market. White LED fixtures have been utilized for display-case lighting for many years now. Although these LED fixtures have taken a considerable market share from fiber-optic lighting when it comes to case lighting, in some applications fiber optics still offer a competitive solution when one is looking for specific optical performance and elimination of heat. In addition, the integration of daylight and sophisticated control systems have increasingly become an integral part of museum projects.
This article was written by David Clinard when he was chief lighting designer at the American Museum of Natural History in New York City. Today, Clinard is principal of Clinard Design Studio in New York City.