Resilience of buildings to extreme weather events

Abstract

Our climate is changing and the results of that are already visible. The two-month period of December 2013 and January 2014 was for England and Wales one of, if not the most, exceptional periods of winter rainfall in at least 248 years. In addition to that, on July 1st, 2015, at Heathrow, Greater London the highest July temperature on record for the UK was recorded.Our buildings are already performing poorly under the current weather conditions. Even the buildings that are performing well now may become intolerable for the occupants by 2080. It istherefore important to find ways to increase the resilience of the current building stock and to identify master planning principles for the new buildings.The scope of this research was to study the resilience of three different types of buildings (high-, medium- and low risk) under extreme weather conditions. The extreme events that wereinvestigated are extreme hot and heavy rain. EDSL TAS, XP SWMM and MicroDrainagesimulation software packages were used in order to estimate the thermal and energy performanceof the buildings and investigate the effects of heavy rainfall.There is clear evidence to show that climate change is happening. According to the UK Climate Projections (UKCP09), we can expect warmer and wetter winters, hotter and drier summers, rising sea levels, and more extreme weather events. These extreme weather events in the UK are likely to increase with rising temperatures, causing among others more substantial rainfall events with an increased risk of flooding. Flooding is currently identified as one of the greatest threats to the UK posed by climate change. In addition to that, the UKCP09 show that means daily temperatures will increase everywhere in the United Kingdom. This will significantly affect the thermal and energy performance of the current building stock.This study presents four case studies where the resilience of the examined buildings is investigated under extreme hot weather events. It looks into the risk of overheating of a school building in 14 locations in the United Kingdom using the overheating criteria defined in Building Bulletin 101 (BB101). It examines three different ventilation modes and quantifies the required amount of cooling loads to achieve thermal comfort conditions. Furthermore, it considers the effect of relative humidity for an office building in London and for the same building, it examines the effect of the window-to-wall ratio on thermal comfort and energy consumption. This study also evaluates the effect of extreme rainfall events on the resilience of buildings and presents two case studies on this. The first one examines the effect of building development on the risk of flooding under extreme rainfall for an area that has a very low chance of flooding by modelling two different scenarios of building development. The second case study investigates the effects of sustainable drainage systems on residential developments under extreme rainfall events.The outcomes of this research present practical approaches of mitigating the effects of extreme hot weather and extreme rainfall events. The research has demonstrated that lower window to wall ratios result in more comfortable conditions and has also shown that a relative humidity control will result in improved thermal comfort conditions for most of the occupied hours during the summer months. This study has also examined a school building and quantified the amount of cooling loads required to comply with the BB101 criteria and presented a comparison between the current and future weather conditions. Additionally, the research results demonstrated that automated control of the opening of the windows results in reduced operative temperatures and improved thermal comfort conditions. This study has also investigated the effects of sustainable drainage systems (SuDS) during extreme rainfall and has quantified the effect of three different types of SuDS (permeable water, rainwater harvesting, and attenuation basins) for a new build residential development. It has also shown that building development will increase the risk of flooding from surface water, even for areas with a low chance of flooding.

Το αντικείμενο αυτής της έρευνας ήταν να μελετήσει την ανθεκτικότητα τριών διαφορετικών τύπων κτιρίων υπό ακραίες καιρικές συνθήκες. Τα ακραία γεγονότα που διερευνώνται η υπερβολική ζέστη και η δυνατή βροχή. Χρησιμοποιήθηκαν πακέτα λογισμικού προσομοίωσης EDSL TAS, XP SWMM και MicroDrainage για την εκτίμηση της θερμικής και ενεργειακής απόδοσηςτων κτιρίων και τη διερευνήση των επιπτώσεων των έντονων βροχοπτώσεων.