Environmental Control in National Trust Properties

Abstract

The paper describes the issues and processes associated with controlling the internal environment in historic National Trust buildings that are open to the public, with the aim of slowing the rates of deterioration of the collections, and decorative interiors, without causing damage to the structure. The paper shows how environmental monitoring is providing knowledge of the building performance prior to any services project and also sets out the current National Trust Environmental Control Strategy. Conservation heating is proving extremely successful at stabilizing environmental conditions and reducing the remedial conservation requirement of the collections. Other control methods, such as buffered microclimates and dehumidification are mentioned briefly, along with the current issues of ventilation, choices of insulation and fuel.

Indoor mould testing in a historic building: Blickling Hall

“…To maintain a suitable environment, the National Trust stabilises indoor hygrothermal conditions at moderate relative humidity and temperature levels using humidistatically controlled conservation heating. In this approach space heating operates when the RH is above a set point of 58–60% and is switched off when the RH falls below the set point, so that a moderate RH can be maintained that is below the threshold for mould growth but not so low as to risk drying and shrinkage of hygroscopic materials [24].…”