HVAC Advice from Museums

July 1, 2007
HVAC systems designed and operated to preserve museum collections are models for controlling any facility's indoor climate

Museums across the globe are time capsules in which objects and artifacts cease to age, a miracle made possible by controlling air quality, temperature, and humidity with great precision. Without advancement in HVAC-system design, the Declaration of Independence would be nothing more than a legend, and the paintings and painters of the Renaissance would be long forgotten.

Whether they display manuscripts, oil paintings, or dinosaur bones, museums must successfully preserve collections through meticulous control over indoor climate. Perhaps no one understands the importance of HVAC design and maintenance better than the museum's faculty and facility professionals. A lot can be learned from the best-in-class HVAC systems that are designed for and operated in these specialized environments.

1. Identify who is using the facility and how it functions; condition spaces accordingly.
Despite the criticality of HVAC design, facility management professionals in museums must still make compromises - especially when (in the case of a renovation or system upgrade) the existing facility and budget create limitations. Clif Greim, principal at Auburn, ME-based Harriman Associates, explains another situation that necessitates compromise: "Special collections should be maintained in a very steady environment [in terms of] temperature and humidity; however, archivists working with those collections are going to complain if it's 67 degrees F. So, what's the real criteria? Typically speaking, people view humidity control as more important than temperature control."

Maintaining consistent humidity levels in libraries, industrial warehouses, retail environments, and many other commercial facilities is just as important as it is in a museum. For example, in 2004, the Journal of Cataract and Refractive Surgery reported that increasing the humidity by 10 percent in LASIK eye-surgery treatment rooms resulted in an additional nine out of 10 patients requiring a subsequent enhancement procedure. In any facility, it's imperative that the mechanical engineer and contractor have a firm understanding of any special needs and requirements of the space; only then can educated and informed decisions be made about what system will meet all criteria.

2. Recognize the impact of the building envelope and the limitations it may pose to the HVAC system.
In a 2005 benchmarking survey conducted among its members by the Groton, MA-based Intl. Association of Museum Facility Administrators, 72 percent of respondents indicated that the museum they worked in was more than 16 years old (36 percent of those reported that their building was 50-plus years old). HVAC systems in these existing - and sometimes historical - buildings should not be designed as if they were located in a new facility. The age and the condition of the building envelope must always be taken into consideration when preparing to upgrade HVAC systems. Consider investing in a professional building-envelope assessment to determine the physical condition of the facility's exterior. By identifying potential problems at their onset, you can avoid structural damage and elevated heating/cooling loads. "Typically speaking, you won't have a successful HVAC system if the envelope that is containing the environment isn't hermetically sealed. It needs to be well insulated - that's really the key," explains Greim.

Controlling indoor air temperature and humidity when a facility isn't sealed and weather tight is a struggle for any professional. With a high degree of humidity introduced into the air, condensation can develop within the building envelope, freeze, and cause accelerated deterioration of the façade. "If we add too much moisture into a space, but there isn't a proper vapor barrier and there is condensation in the envelope, we can also get mold growth inside the walls of the building," adds David Brooks, principal, McGuire Engineers Inc., Chicago.

3. Control IAQ by adjusting levels of outside air and applying appropriate filtration solutions.
Air quality is largely dependent on the amount of outside air introduced into the indoor environment. Too much moisture in the air can be burdensome to a museum's HVAC system as it works to dehumidify the air to a level deemed appropriate for the preservation of objects. Use of desiccant dehumidification technology is gaining in popularity. In addition to museums, operating rooms, pharmacies, offices, retail stores, and industrial sites are effectively employing the technology to control humidity and keep mold at bay.

To keep from conditioning spaces with outside air when they are unoccupied (which will tax the HVAC system), many museums are monitoring CO2 levels and only bringing in outside ventilation when occupied. "If certain galleries are closed, don't bring in any burdensome ventilation air unless people are in the space," explains Greim. Controlling specific areas depending on occupancy (via HVAC zones) in any facility is an energy-efficient strategy.

Filtering out contaminants (e.g. NOx and SOx emissions from vehicles) is essential to protecting art/artifacts and providing healthy, clean air for occupants. When the budget is tight, opt for particulate filtration, advises Brooks, although, ideally, chemical filtration is beneficial as well.

4. Install a system with budget constraints and maintenance plans in mind.
Museums often operate on lean budgets and, when it comes to the expense of a new HVAC system, scrutiny is expected. Facility administrators are faced with the same question that their colleagues in other buildings face: Pay substantial first costs for a high-performance system that won't require as many upgrades or pay less now and upgrade the system later? The answer is dependent on three things: the amount of money that is available now, the amount of money that will be available later, and balancing the complexity that's necessary with the operating capabilities of the staff. "We've worked with certain institutions that felt it would be appropriate for us to design a system with a higher first cost because they can never get enough money for maintenance," says Tony McGuire, president, McGuire Engineers Inc. The reverse can also happen when museum facility administrators don't have much available capital, but anticipate that funding will be available later for upgrades and maintenance.

Museums vary greatly in size and staff; for some institutions, the executive director is the same as the facility manager. "Engineers have a tendency to be very complex and [provide systems that] can go beyond the abilities of the operating personnel," explains Brooks. All facilities should keep this advice from Brooks in mind: "Make sure [the new system] is within the operational capabilities of the users."

Jana J. Madsen ([email protected]) is managing editor at Buildings magazine.

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