HVAC systems, the primary weapon for preserving library and archival materials, also regulate humidity and temperature and suppress mold growth, performing these tasks consistently throughout storage areas. Libraries and archives have found that the best conditions are maintained by constant-volume, all-air HVAC systems whose filtration, dehumidification and humidification, maintenance, and monitoring tasks are handled by central (rather than distributed) stations. For those libraries and archives that are having HVAC systems installed or built in, it is important to consider specifications that will produce a continuous conservation environment.

Some library materials require more stringent storage conditions than are required for paper-based materials. Motion picture film, color film, and microfilm, for example, must be kept in a cool, dry environment. In this case, even if HVAC is not practical for a larger storage space, a small vault or cabinet with good controls should be used. Such a cabinet should maintain a low temperature, around 20°C. More important is the level of humidity, which should not exceed 35 percent. This can only be achieved through the use of a desiccant such as silica gel. Silica gel can be conditioned to absorb humidity within a tightly closed cabinet. When the silica gel becomes saturated, the humidity can be heated out and the gel used again.

The most common type of film material that libraries must store is microfilm. When microfilm is produced to archival standards, three generations of film are created, with the original camera negative regarded as the archival copy. It is imperative that the negative be protected by appropriate storage.