Developing an Adaptive Climate Control Strategy and Programme Monitoring Micro-change in Wooden Heritage Objects

ABSTRACT Recent environmental guidance in the cultural heritage field reflects the increasingly important objectives of sustainability and reduced carbon footprint. New and revised guidance from organisations such as the Bizot Group, IIC/ICOM-CC, AICCM, and ASHRAE share common principles, including consideration of passive low-energy environmental control methods, adoption of realistic target conditions given the building envelope and exterior climate, and support for broader environmental parameters for many classes of objects. Motivated by an interest in energy savings and security, as well as broad organisational involvement and buy-in for implementing environmental change, the National Gallery of Victoria (NGV) in Melbourne, Victoria, is adopting the Bizot Green Protocol (BGP) for its collection and for outgoing loans. Initial NGV trials of a transitionary ‘soft Bizot’ setting – temperature between 20°C and 23°C with 24-hour fluctuations of no more than ±1.5°C and relative humidity between 46% and 56% with 24-hour fluctuations of no more than ±4% – demonstrated reduced energy use. The NGV and the Getty Conservation Institute are collaborating to examine object response during this environmental transition. In addition to visual monitoring of several works in the collection using macrophotography, acoustic emission (AE) monitoring will be carried out on a Flemish retable consisting of carved and polychromed wood and oil paint. AE monitoring is a highly sensitive technique that measures energy, in the form of transient elastic waves, released by and propagated through a material such as wood that has undergone brittle cracking. This has the potential benefit of detecting environmentally induced micro-changes in an object before damage is visible to the viewer.