The Impacts of Climate Change on Historic Buildings: Heating and Overheating in the Tower of London

The built environment requires retrofitting on a massive scale to both mitigate the impacts of climate change and adapt to future conditions. Buildings of high thermal mass offer useful insights into the limits of passive measures in futureproofing against overheating. Historic buildings typically have a higher thermal mass and also offer a paragon case to study improvement options that do not compromise heritage or character. This paper focuses on the Tower of London as a case study. Data from pre- and post-COVID-19 allows insights into the building performance in the absence of end users. A thermal model is calibrated to accurately represent both the physics of the building and the impacts of its occupants in use. Future weather files then test the extent to which the building’s thermal mass can mitigate against overheating under a range of climate warming scenarios. The results suggest that prolonged heat waves pose a serious risk to passive mitigation strategies as the mass of the building stores heat it cannot shed overnight. These scenarios also reduce the heating demand in winter. The results suggest that the built environment faces subtle design challenges in understanding the limits for passive design techniques versus the need for cooling in a warming climate. For the Tower in particular, a significant increase in overheating is likely in the coming decades.