The continuous monitoring of temperature and humidity is extremely important whether or not the library/archive has climate control systems. In buildings with an HVAC system, its performance can be monitored and corrective action taken when needed. If the library does not have an HVAC system, an accurate record of temperature and humidity through all seasons and conditions can provide the essential data for designing a future system and can indicate where and when remedial action should be taken.

Monitoring at its simplest consists of taking regular readings of a thermometer and a hygrometer, calibrated with a psychrometer, and noting the changes throughout the day. Although there are now sophisticated instruments for checking temperature and humidity—such as hand-held electronic hygrometers that measure both—these tend to be labor-intensive and not used at night or during holidays. This is also the disadvantage of basic thermometers, dial-type hygrometers, and humidity strips. Automatic monitors, such as recording hygrothermographs and electronic data-loggers, are more useful.

Click on the links below to learn more about monitoring instruments.

1. Recording hygrothermographs

2. Psychrometer

3. Data-loggers