Installation view, Yinka Shonibare Selects: Works from the Permanent Collection exhibition, Cooper-Hewitt, National Design Museum, Smithsonian Institution, 2005. Photo: Andrew Garn, © Smithsonian Institution, reproduced courtesy of the artist, Stephen Friedman Gallery, London, and James Cohan Gallery, New York
At a recent salon sponsored by Urban Green, industry pros discussed new strategies and the changing landscape for achieving energy efficiency in buildings that have long been exempt from such standards – museums and galleries. Lighting designers and engineers discussed how their clients are achieving savings by evaluating heating and cooling loads, taking advantage of current high-performance LED equipment, and reexamining the standard “50/70” rule (50% relative humidity and 70 degrees Fahrenheit air temperature) for environmental controls. In his discussion, “Energy Use in Conservation Environments,” William Lull from Garrison/Lull Inc. discussed the standard operating assumptions and mechanical systems of many museums and galleries. Typically, the levels of environmental control and causes of damage include major risk, such as fire or flood; biological attack, including vermin and mold; uses such as handling and light exposure; and protection from mechanical, chemical, and photochemical vectors. Most institutions believe they achieve environmental control if they prevent damage or biological attack, but lighting, heating, and cooling represent the largest opportunity to achieve savings. Lull’s suggested strategies include identifying realistic goals for heating and cooling and benchmarking, or comparing, results. He also recommends reducing loads, greater system efficiency, improved operation, and examining utility sources for opportunities and cost savings. Greater efficiency can be achieved by relaxing or reducing the acceptable range of temperature or humidity, depending on the collection. The “50/70” standard is being challenged now that its affect on energy expenditure and cost is becoming an issue. Institutions need to consider mechanical, chemical, and photochemical deterioration factors and how they affect their collections, for example, use existing warm/dry conditions, such as attics, for storage of metals. Lull suggests allowing broad humidity conditions consistent with past temperature and relative humidity range, holding cooler and drier conditions for paper and organics to reduce the rate of chemical deterioration, and using only air circulation and ventilation in unoccupied spaces to suppress humidity and mold for collections normally kept in ambient conditions. The primary loads on systems are lighting, dehumidification, and humidification. Typically, if the air is too dry, it must be humidified. If it is too moist, it must be cooled to dew point and then reheated if too humid. When using outside air, all aspects of heating and cooling are involved, causing heavy demand on the system. Lull discussed how several of his clients reevaluated their old assumptions and came up with new ways to achieve stable environments yet save money. At the Hay House, they chose to maintain a temperature of 70-72 degrees and a humidity range of 50% +/- 5% for the museum wing, but for period rooms maintained a temperature of 68-75 degrees and 30-60% relative humidity. For the storage of rare books at Harvard, book storage was set at 40-50 degrees (which saves money in a cold climate) and humidity levels at 30-60%. Variable frequency drives (VFD) were used on fans, and hot and chilled water for maximum efficiency. At Stony Brook, controls were reduced to three: off, re-circulate, and ventilate, depending on conditions. Settings grab outside air only when conditions are favorable. The only control is a fan. Mr. Lull notes that micro-climate generators are the new frontier in interior case climate control. These devices aim to control the immediate climate inside cases by precisely regulating humidity, rather than the entire gallery. Chad Groshart from Atelier Ten discussed high-performance, low-energy lighting design. Museums have long prized high performance in color rendering and low levels of UV output over lamp life and concerns about heat generation affecting overall gallery climate. Halogens are the most popular lamp types, as they offer good color, low UV, and low cost. However, they burn very hot. Eighty percent of the energy is turned into heat, which means a high bill for lighting energy as well as for cooling the space. Other lamp options include flourescents and LEDs. Flourescents are desirable for their efficiency and have a long lamp life and low cost, but have not worked well in museum settings where greater controls are required. LEDs now offer 97+ CRI. They have less UV than any other source. Most use less than 1/10 watt of energy. An LED lamp has 50,000 hours of life verses about 4,000 hours for halogen. Lighting controls offer a way to maximize efficiency. In a case study at Yale, a small jewelbox-like display of brains in jars was a showcase for low-energy lamps and strategies to reduce light use. Visitors push buttons in each case and get five minutes of light. All lights are on a timer, so if there are no visitors, there are no lights. There is a groundswell towards the use LEDs in museums. Several institutions are engaging in modest, grass-roots testing, such as San Francisco MoMA, the Getty Institute, American Museum of Natural History, and the Norton Simon. The Smithsonian American Art Museum participated recently in a Gateway study conducted by the Department of Energy. The LEDs tested had one-third the energy use and 75% savings compared to halogens, with no visible difference in CRI. The Getty has conducted lots of research comparing LEDs to halogen, and has found no difference or even slower deterioration to objects by LEDs. In their technological infancy, LEDs suffered from early burnouts. Groshart cautions to use only the highest quality light engine (he recommends XICATO) and the most reputable manufacturers, such as LSI (known for being experimental), Phillips, and Lumenpulse. As institutions put their toes in the water and more demand is placed by museums on performance, the industry response will provide more and more viable options. Eventually there will be a huge shift to LED lighting in museums. The last speaker, from SOM, reviewed tightening standards according to ASHRAE 90.1, Appendix G. (ASHRAE is the American Society for Heating, Refrigerating and Air-Conditioning Engineers, and is the benchmark for commercial building codes in the United States and a basis for many international codes.) Museums are not exempt from energy standards – in LEED version 2.2, they must achieve a baseline of 1.0 watts per square foot to earn credit 1 in the Energy and Atmosphere category. One SOM client, the National Museum of the U.S. Army, wanted to achieve 5.6 watts per square foot. But SOM’s analysis, which showed their client that this amount of watts per square foot would result in using 29% of the entire building’s energy, were eventually convinced to reduce their usage to 2.5 watts per square foot, although it was a tough sell.