Church pipe organs: Historical tuning records as indoor environmental evidence

Churches are increasingly challenged to balance rising thermal comfort expectations with the microclimatic requirements for conserving heritage artefacts. Few studies have established the trends of rising indoor temperature and illustrated its perilous relationship with conservation from a historical perspective. This study discovered a new data source, i.e. the organ tuning books that document the historic environmental conditions of churches. Pipe organs are highly complex musical instruments made of diverse materials. Their tunings are usually scheduled twice a year after a seasonal change as pipes of disparate construction react to temperature and humidity fluctuations. Indoor temperature and humidity are usually recorded in organ tunning books during the tuning sessions. Quantitative data in the form of temperature and relative humidity were extracted from 18 organ tuning books in the UK. Twelve tuning books belonged to Sir Christopher Wren's City of London churches; the other six belonged to churches across Nottinghamshire and Derbyshire. The historical records of temperature and humidity provide valuable data and insights for assessing the dynamic trend of the indoor church environment. Initial data analysis reveals a significant conservation risk as the increased and fluctuating indoor temperatures and relative humidity will endanger historic buildings and their artefacts.