How do you deal with a less-than-perfect heating and cooling system? Not every institution has a central environmental control system, nor does every institution have the resources to drastically improve its existing system(s)—even if the need for better climate control is clear. If installation of a central HVAC system will not be feasible in the near future, you will need to implement low or no-cost actions in the meantime.
Take a few moments to reflect on the scenario below. What would you do in this situation? Click on Show Answer to review some options.
Scenario: The archival collection of the Town of Fairview is housed in a small room on the second floor of Town Hall, with additional storage in the basement of the building. The Town's new archivist discovers that the basement is quite damp year round, and that the archives room upstairs becomes very hot and humid in summer, and hot and dry in winter. The building has a heating system but no cooling system, although several of the offices have window air conditioning units.
Question: What might the archivist do to improve climate conditions for the archival materials?
The archivist should begin lobbying to remove the archival materials from the basement and the second floor to a more moderate storage space on the first floor or elsewhere. The archivist should also immediately purchase at least two min/max thermohygrometers and begin a monitoring program in both storage areas. In the meantime, a dehumidifier should be installed in the basement (connected into the plumbing system). The heat should be kept low in the second floor storage room in winter, to keep the humidity relatively moderate. A window air conditioner in the second floor space might cause more harm than good, since it could not be run all the time. The archivist should ensure that all collections are enclosed in archival boxes, which will protect them somewhat from climate fluctuations and extremes.
"Letting the outside in" can contribute to the deterioration of collections. Look for air leaks around windows, doors that don't close properly, and dampness in the basement. Simple repairs and regular maintenance can make a big difference. Improvements can be made by adding weather stripping around doors and windows, insulating the attic, or installing storm windows. Simply wrapping steam and hot water pipes with insulation can minimize the effects of these localized, intense heat sources.
Move vulnerable collections out of damp basements or hot attics, and away from exterior walls. Rearrangement can improve air circulation and help maintain a uniform temperature and humidity throughout the space. Remove collections from beneath overhead water sources, away from heat registers, and out of direct light. And don't store anything on the floor. Store your most sensitive or fragile materials in the space where climate conditions are the most stable. Can you identify this space in your building?
In winter, you should keep the heat low to ensure that humidity in the building does not fall too low. In summer (and parts of spring and fall), dehumidifiers should be used if needed to keep the relative humidity low in collections storage spaces. Dehumidifiers should be self-draining and connected into the plumbing system. Local controls like these require staff vigilance to operate the equipment and rely on a good environmental monitoring device to regulate proper conditions.
It can be very difficult to maintain a constant temperature and relative humidity (even with an HVAC system) in northern climates with cold, dry winters and hot, humid summers, so the concept of seasonal drift has been developed. This allows the temperature and humidity to gradually rise during the spring and summer and gradually go down during the fall and winter. Frequent large fluctuations are avoided, and temperature and humidity never become extreme. The Environmental Guidelines for the Storage of Paper Records (NISO-TR01-1995, available from NISO) recommend that conditions should go no higher than 72°F and 50% RH in the summer and no lower than 57°F and 35% RH in the winter.
Even in the absence of good climate control, storage in preservation quality enclosures and safe furnishings will help protect your collections from premature chemical and physical damage.
Using preservation-quality enclosures and boxes effectively creates a microclimate around collection materials, buffering them from sudden changes in the temperature and humidity. A properly fitted enclosure will also help keep out dust and pollutants.