1 Modelling the Impact of Climate Change in Schools: the Issue of Overheating David Coley and Tristan Kershaw Centre for Energy and the Environment Physics Building, Stocker Rd, Exeter, EX4 4QL, UK Tel. (01392) 264144 E-mail d.a.coley@ex.ac.uk Many buildings demonstrate levels of overheating close to the maximum allowed by the building regulations. Therefore there is the potential that such designs will breach the regulations under the climatic conditions in the UK predicted as a result of climate change. In order to see if this concern is well founded, weather files representative of the possible weather between 2020 and 2080 were created and applied to a thermal model of a school. Unlike other work done on this subject, 28 variants of the basic design were studied in order to see if a consistent message would arise regardless of thermal mass, ventilation, glazed fraction and U-value. In addition, more extreme climate change scenarios were studied than is usual and a sensitivity analysis carried out with regard to the main climatic driving forces. In total 252 building/weather scenario combinations were studied. The results show that all of the building variants examined will have significant overheating by 2080. In light of these results it is suggested that the basis of school architecture will have to be revisited, as simple adjustments to the parameters listed above are unlikely to prove adequate. We have found the first indications that changes in the internal environment within buildings will follow linear trends under a changing climate (i.e. in direct proportion to the amount of climate change), and that the constant of proportionality that this implies (which we term the climate change resilience coefficient) can be used to characterise the inherent level of robustness of a design to a changing climate. 1. Introduction Although currently there is no requirement for building designers to take climate change into account, given the lifetime of most buildings and the predictions by UKCIP [1] and others of the future UK climate, it would seem sensible to have some understanding of how a building is likely to be affected by climate change. Given that we often find little margin between the predicted internal environment and the requirements of the building bulletins for schools it seemed sensible to study the impact of climate change on the internal environment of schools and in a way that accounts for differences in thermal mass, ventilation philosophy, glazed fraction and level of insulation. It also seemed sensible to include the possibility of more extreme climate change than that included in the work of UKCIP02. TM36 (Climate change and the indoor environment: impacts and adaptation) [2], briefly looked at overheating in schools by examining two case studies, a single storey design typical of 1960s constructions and an advanced naturally ventilated school (both for a single climate change scenario). Here we look at 28 designs and nine climate change scenarios (current climate, the four UKCIP emissions scenarios and four custom scenarios). We also attempt to discover the sensitivity of a school building to incremental changes in the weather driving forces. In the following sections the building regulations are described, details given of how future weather files have been created, how more extreme scenarios are developed, the scenarios are summarised by descriptive statistics, the different school studied detailed and the results of the modelling are given. We also present a possible measure of robustness to a changing climate. 2.The Building Regulations The UK’s building regulations, like much legislation, start from a position of pragmatism. For overheating this means that (a) a certain amount is allowed, and (b) it is a computer model of the building that is assessed not the building itself. If occasional overheating were not allowed or the requirement was for the building to pass in use, than a particularly hot summer, or the placing of a large amount of heat producing equipment in a building could be presented as a failure of the architecture and a fine day for lawyers. Schools for example are allowed to overheat for 120 of the occupied hours over the summer period, where overheating is defined as an air temperature in excess of 28°C. There is also the need for the maximum temperature not to exceed 32°C and the mean internal/external temperature difference during occupied hours not to exceed 5°C. Although the choice of 28°C and 120 hours was based on some consideration of human psychology and thermal