The Use of Thermal Mass to Mitigate Overheating in an Affordable Low-Energy Pre-fabricated Timber House

Stricter building regulations aimed at reducing heating demand in the UK housing have resulted in buildings which are more sensitive to energy inputs and therefore present higher risk of overheating. Dwellings built using Modern Methods of Construction, which are expected to play a significant role in the house building industry in the next few years, are considered to have a higher risk of overheating because they usually present lower levels of thermal mass. The levels of thermal mass relate to how a building may provide thermal inertia and therefore help control temperature fluctuations. The Nottingham H.O.U.S.E., a prefabricated timber modular building with low levels of thermal mass is examined in terms of overheating occurrence. Instead of expensive and/or laborious methods of integrating extra thermal mass, the authors investigated, through advanced numerical modelling techniques, the performance of the thermal mass provided in different quantities of Rigidur H. This is a high density affordable and easy to install fibreboard. Measured and modelled findings suggested that the Rigidur board was effective in mitigating overheating in many cases, particularly when associated with other strategies such as natural ventilation, and should be considered as part of the overall design strategy.