Improving wind-tightness for energy retrofits in mid-century timber churches

Historic timber buildings often suffer from significant air infiltration, leading to energy losses and reduced thermal comfort. This issue is partly due to the anisotropic properties of wood, which cause shrinkage and swelling, requiring continuous attention to material junctions to ensure airtightness. Furthermore, in the case of typical timber frame construction – except for log buildings – the load-bearing structure is, if at all, only part of the building envelope, which includes the potential for leaks. Particularly in buildings constructed between the early modern period and the 1960s, insufficient wind-tightness is a common problem. At the time, effective insulation materials were scarce, and those used often had limited thermal performance. While adding insulation raises questions of historical preservation, the installation of an exterior wind barrier is a key measure to reduce heat loss and improve comfort. Sealing measures significantly reduce draughts and energy consumption. When paired with simple ventilation control systems, they can also minimise condensation risks. Importantly, such interventions can in certain cases be carried out without compromising the historic value of the structures. Case studies confirm that targeted wind-tightness improvements, in combination with minimally invasive insulation strategies, offer an effective path towards enhancing the energy efficiency of historic timber buildings.