Guideline 19.3

Guideline 19.3: Exhibit design and structural modifications protect objects from inappropriate temperature and relative humidity

How can design protect objects from inappropriate temperature and relative humidity?

By allowing for good air circulation and insulating the exhibit space, exhibit design and construction can create a more constant environment in which temperature and relative humidity (RH) are more easily regulated. Conversely, inappropriate design choices can expose objects to harmful climatic conditions. The following design strategies can enhance climate control efforts:

Exhibit design can include structural modifications that will help to seal and insulate the exhibit location and stabilize the environment. Such modifications include:

• Incorporating a vestibule at the exhibit entrance to control airflow.
• Enclosing the exhibit area with well-fitting doors.
• Blocking unnecessary windows and doors with insulating material.
• Caulking or gasketing doors and windows to limit air infiltration through cracks and gaps in the building
• Blocking the transfer of humidity by installing an effective vapor barrier where missing (e.g. walls, ceiling and floor)
• Provide unrestricted airflow for the heating and air-conditioning systems
• If it is not possible to eliminate all windows, minimize their impact by using double or triple glazing on windows to help stabilize the room climate in winter climates, or filtered glass to eliminate excessive heat ingress.

A properly designed exhibit case can provide effective protection from RH on a micro scale:

• A well-sealed exhibit case can protect humidity-sensitive objects from constant fluctuation of RH. Because the rate of air exchange is decreased, the environment inside the case is stabilized, protecting objects from the worst ambient humidity swings.
• The inclusion of silica gel and other humidity control products can stabilize the humidity level inside a sealed case in exhibit spaces that have little or no humidity control.

[For more information on case design, see Standard *.]

The layout of exhibit furniture should not interfere with proper functioning of climate controls:

• Ensure that furnishings do not block proper air circulation

Tall furnishings such as panels, shelving, and tall cases, should not create obstacles to the circulation of air.

• Ensure cases are situated in locations that will not compromise climate controls:

Cases should not touch a building’s outside walls: exterior temperatures could affect the internal temperature and humidity of the case. Similarly, framed works should not be hung directly on external walls. (When the location of a case or frame cannot be changed, consider the use of insulating construction materials and thermal pane glass.)

Cases should not be placed near heat sources such as radiators, heaters or in front of windows

Exhibit layout should allocate the most climatically stable locations in the exhibit area to sensitive objects:

• Place sensitive objects in the most stable locations--those locations in the exhibit area that are least prone to humidity and temperature fluctuations.
• Do not place temperature or moisture sensitive collections near sources of temperature or humidity fluctuation:

Avoid placing objects in the path of direct sunlight, against external walls, near doorways, windows, air vents, exposed pipes, or heat sources such as radiators. To prevent damage from desiccation and dimensional change, do not overheat objects by placing them too close to a lighting source. Objects should be placed at least 36 inches from incandescent or tungsten halogen light because of heat buildup and illumination levels.

Avoid using materials for construction, props or room furnishings that could increase RH.

• If organic material is used for props, ensure that it is dry.
• Do not use water to create weather and water effects; instead utilize synthetic materials.
• Indoor plants can interfere with humidity levels.

(All of the above can create hazards besides affecting humidity levels. For more information on safe exhibit materials and furnishings see Standard *.)