Energy Savings & Collections Management

By Peter Herzog, Herzog/Wheeler & Associates - July 2008

The rising cost of energy is putting pressure on cultural institutions to look for ways to reduce energy consumption. In most museums, libraries, and archives, areas dedicated to collections storage typically receive conditioned air 24 hours a day, seven days a week, and are maintained at more stringent temperature and humidity conditions. As a result, these spaces consume more energy than almost any other areas. Our years of performance measurements indicate that a typical 10,000 square foot collections storage area costs between $20,000 and $50,000 per year to condition. As a result, cultural institution facility managers are asking collection managers to consider energy-saving alterations to the operation of storage area HVAC systems.

Energy-saving strategies under consideration may include reducing the quantity of outside air or the quantity of the total conditioned air during periods when the spaces are unoccupied. Another strategy may suggest reductions in the amount of sub-cooling and reheating during periods when the outside air dewpoint temperature is low. It may also be suggested that temperature and RH set points be altered during certain seasons of the year.

Most energy-saving alterations to HVAC systems, their control, or their method of operation, will result in some change in the space temperature and/or RH. Some of these changes can be seriously detrimental to collections and should be avoided, while others will be inconsequential and justified by the resulting energy savings.

Determining if these or any other energy-saving strategies are viable requires thoughtful consideration of the architectural characteristics of the storage area and the mechanical characteristics of the HVAC system that serves the space. While some facilities may present no viable savings opportunities, experience has demonstrated that many could reduce their energy consumption by 10% to 30% through alterations to the operation of existing HVAC systems, and do so without posing significant risk to collections.

Through our work with IPI on a number of projects with major cultural institutions, several simple considerations regarding energy efficiency in design and operation of systems effecting storage spaces have emerged. Suggestions we recommend during the building design process include:

  • Design equipment to be efficient at low loads (the majority of time when it isn’t the warmest or most humid outside).
  • Design to keep outside air to code minimums.
  • Consider a design that dehumidifies only the outside air not the total air.
  • Plan to keep collection storage areas separate from human occupancy spaces.
  • Install occupancy sensor control of storage area lighting.
  • Design ducts to reduce fan energy.
  • Minimize pressure drops (and consequent fan energy costs) due to particulate and gas phase filtration.

Once a building has been designed and built, operating savings become the central issue. Our experience has shown that significant opportunities to reduce energy costs and provide improved preservation quality for collections environments almost always exist if you know how and where to look. Suggestions for operational savings include:

  • Don’t heat to human comfort temperatures in collection storage areas in the winter.
  • Control for a safe RH and the coldest feasible temperature.
  • Avoid reacting to fluctuations within the envelope of safe operating conditions.
  • Watch for unnecessary sub-cool and reheat.
  • Minimize lighting operation and other sources of heat in storage areas.
  • Make monitoring part of a long-term collection management strategy.
    • Use IPI’s preservation metrics to identify underperforming spaces and opportunities to reduce energy consumption.
    • Monitor any changes made in mechanical system operation to determine if the change poses a risk to collections in storage.
    • Work with facilities managers to determine if the savings potential of the change is justified in light of its effect on collections.

After years of research into the chemistry and physics of environmental threats to stored collection materials, IPI has developed a system of tools that can be used to manage the environment for preservation. This system consists of specially designed temperature and RH data loggers to monitor storage conditions, a simple method for transfer of temperature and RH data to a customized web-site or desktop application for analysis, and software that performs calculations, which provide a deeper understanding of the effects of storage climates on collections. The result is an integrated hardware/software system designed in every detail for the specific needs of collection care in cultural institutions.