Temperature cannot be avoided or removed. But it does need to be managed to maintain stable conditions – neither too high nor too low.
Temperature has a correlation with chemical reaction rates, which proceed more quickly the higher the temperature. Lower temperatures are therefore preferable, but not so low as to cause synthetic or organic materials to become brittle. The relative humidity (RH) will vary in response to fluctuating temperatures, another reason a stable temperature is desirable, as humidity can harm materials.
Conservators monitor both moisture (RH) and temperature in order to determine whether conditions are likely to be damaging to artefacts and whether action needs to be taken to modify it.
In a historic building it is difficult to control the heating levels to suitably cool and stable conditions, and so, because temperature affects humidity, the moisture content of the air in the Western Art Galleries is modified by stand-alone humidifiers. They inject moisture to increase the RH when the temperature rises in the summer or supply extra moisture during the winter when cold external air filters into the galleries causing very dry conditions.
The temperature set-point in museums is usually based on a combination of being low enough to limit reaction rates but warm enough to be an acceptable level for human comfort.