Collectively, the ISO standards for individual media contain seven different temperature recommendations. To simplify the evaluation and planning of storage conditions for mixed media collections, the recommendations below divides the range of possible temperatures into four categories: ROOM, COOL, COLD, and FROZEN.
Even though each of the four categories represents a range of temperatures, it is useful here to define ROOM, COOL, COLD, and FROZEN by single “anchor-point” values (It should be remembered that, in reality, the effect of temperature on decay rate is a continuum. The higher the temperature, the faster the decay, and vice versa.) Using the figure to the right and data gathered through an environmental assessment, you should be able to place your storage environment in one of these four categories. It’s very likely that your storage temperature is not precisely one of the four shown in the figure to the right. In this case, the following rules of thumb should help you decide where your environment fits: