Functional fires in historic buildings: Impact on environmental conditions and response of timber objects

Open fires can enhance visitor experience by recreating authentic sights, sounds, smells and warmth but they also influence the environment that they heat. This thesis reports the environmental conditions inside a traditionally constructed, solid walled building at National Museum Wales, St Fagans when heated via open fires lit daily or banked in overnight. It evidences the environmental response of the building, the build-up and dissipation of heat in the chimney breast and offers a 3D understanding of relative humidity distribution. This data informed further laboratory study of the moisture uptake and loss of European Oak (Quercus robur) samples taken from historic furniture with original finishes. The findings demonstrate the ability of the open fire to heat the fabric or the room and maintain a humidity under 60%RH over a period of time after the fire has gone out. They evidence that slow burning, banked in fires offer more heat output through the night than no fire, but also draw in more external air, causing a more uneven humidity distributions. A updated method for recording heat output of the chimney breast and calculating the open fire efficiency was devised utilising infrared imaging. Response of oak samples to environmental changes was found to be slower than expected, yet offered understanding of smaller daily changes. It suggests that moisture response of the oak to daily fluctuations are limited to the outer layers of the wood. It was also found that coatings on timber samples influence the response of wood to environmental changes. These findings have been used to advise management practices in running fires in historic properties at St Fagans.