Microclimate monitoring in museums: a practical guide for the deployment of sensors

Microclimate (i.e., the climate surrounding an artwork) directly and indirectly influences the chemo-physical and structural properties of materials. Microclimate studies are evidently pivotal for the preservation of cultural heritage and must be conducted minimising occurrences that could lead to misleading conclusions and hence to not proper management of conservation spaces. The first issue is the choice of microclimate sensors. This issue can be overcome by following recommendations provided by EU standards (EN 15758:2010; EN 16242:2012; EN 16682:2017). The second issue is related to the number of sensors to be employed, but this depends on the tight budgets of museums, that can be hardly solved. The third issue is the choice of sampling points where to deploy sensors correctly. The most common practice is based on the operator’s experience and expertise involved in that task [1]. However, a practical guide can be useful to support the choice. This contribution aims at suggesting and describing procedures to be adopted for a proper deployment of sensors based on the number of available sensors and under different Museum Scenarios (MS). The latter refers to the classification of the museum into its corresponding most suitable Museum Scenario. The decision making involves a multidisciplinary discussion among museum manager, conservator and conservation scientist. We have identified two possible circumstances: a) artwork-related deployment (i.e., there are as many sensors as the number of artworks) and b) artwork-envelope-related deployment (i.e., the number of available sensors is less than the number of artworks). The artwork-related deployment is advisable when the artwork is often moved from a museum to another one or deserves of specific care. This way, the artwork has its own climate fingerprint that can be monitored even during restoration, transport and temporary exhibitions. The artwork-envelope-related deployment is usually the case of permanent collections, and, according to MS associated with the museum, the related procedures can be further subdivided into basic (MSI and MSII) and advanced (MSIII and MSIV). Advanced procedures [2] are preferable over basic procedures when several time series of microclimate data have been collected for at least one calendar year in several sampling points. Every time microclimate field campaigns can be performed, the protocol for MSII and MSIV are preferable over those for MSI and MSIII, respectively. All these procedures make it possible to design where to deploy sensors both in the case of an initial deployment and of optimisation of already installed sensors. They were effectively applied during the demonstration phase to museums involved in EU H2020 project CollectionCare (grant agreement No 814624 [3]) which house permanent collections. Once microclimate observations are collected, conservation scientists should carry out an adequate data analysis for the assessment of the climate-induced conservation risks. The last step is the fourth pivotal issue of the microclimate monitoring.