Safe microclimate thresholds for photographic and cinematographic media: a new challenge in the era of climate change

Vulnerable collections such as photographic and cinematographic media can be preserved in historical buildings (which generally have poor thermal insulation, low moisture buffer, and energy demanding air conditioning systems) or in purpose-built spaces, which, differently, are more efficient. Regarding the vulnerable collections, we are focusing on films in cellulose nitrate and cellulose triacetate and on photographic media, in particular the paper prints. In general, storage in a frozen or cold environment for films is encouraged, because at lower temperature the kinetics of the chemical degradation reactions decreases. For paper prints we have to avoid the acidification of the paper support. According to the policy framework, we note heterogeneity and great variety of thresholds, but it is necessary that temperature must be lower than 15°C for films, and 20°C for paper prints. As for relative humidity the maximum suggested RH is 50% for both films and paper prints. It is very important to follow guidelines that improve the energy performance of the building, because this also allows for greater conservation of the cultural heritage preserved internally. The EN 16883:2017 concerns historical buildings and focuses the attention on the climate changes which can have an effect on hygrothermal and load risks. It is necessary to reduce the energy demand, reduce greenhouse gas emissions, and maintain indoor conditions suitable for collections.