Building performance evaluation of a 14th century Pargetted House: hygrothermal comfort and energy efficiency

Building performance evaluation (BPE) provides the tools to begin to understand the operational efficiency and resultant occupant satisfaction of the built environment. This is particularly important with historic and traditionally constructed buildings, where perceptions of their performance are often based on preconceptions and generalisations. It is therefore important to undertake BPE of these buildings in order to establish their actual performance and inform the often difficult decisions regarding their ongoing use. This paper presents the BPE of a 14th century timber-framed house, with 17th century decorative pargetting in Saffron Walden, Essex. In situ monitoring and digital simulation were used to assess its current performance and inform the ongoing conservative repair work. The results show that although the thermal conductivity of the pargetting is not particularly low, the increased thickness, and more importantly the sealing of the commonly poor junction between the timber-frame and infill materials, do result in an external envelope with a higher thermal performance than many historic timber-framed buildings. The simulations show that whilst applying internal wall insulation would further improve this performance, it would also increase the risk of frost damage. This highlights the challenges of sustainable building conservation and the role of BPE.