Assessing occupant comfort in historic churches when using localised heating systems

Historic churches often struggle to meet modern expectations of comfort, despite installation of relatively modern heating systems. With a focus on climate change and the emissions associated with fossil fuelled space heating, guidance to churches has been to heat the occupants rather than the building fabric. Seeking to quantify the effect that local and radiant heating systems have upon occupants in a historic church, this study uses a software model to predict comfort, expressed as predicted mean vote (PMV), for several different heating systems and scenarios. The PMV predictions from the model have also been calculated manually using an Excel PMV calculator as verification of the software output. Using a mean radiant temperature (MRT) tool, radiant systems are simulated, with the results utilised in the manual calculations to demonstrate an increase in comfort when using local heating options. In several instances PMV could be increased to between -0.5 and 0.5. This increase allows lower background temperatures to be realised within the church, opening up the potential to use alternative heating systems such as heat pumps. Such choices are aligned with UK Government ambitions for decarbonising heating. Further work related to activity and clothing levels of occupants will enhance understanding of the benefit of local and radiant heating options.