Passive cooling in a hotter world
Reported by Mala Virdee, PhD student in Computer Science and Technology, University of Cambridge
As part of the Cambridge Zero Climate Change Festival 2022, a panel of experts from academia and industry gathered to discuss the challenges and opportunities associated with the implementation of passive cooling strategies in the UK’s built environment.
Climate change is predicted to make heat waves more frequent and intense in the UK. This summer, an extreme heat wave saw temperatures exceeding 40C recorded for the first time. The widespread disruption caused by the extreme temperatures highlighted that the UK is not sufficiently prepared for the impacts of climate change, underscoring the urgent need to develop resilience to higher temperatures. In particular, it will be critical to ensure that homes and workplaces can remain at safe and comfortable temperatures under future conditions.
Passive cooling is an approach to building design that enables interiors to be cooled with low or zero energy consumption. This includes optimal choice of building site, orientation and layout, installing external window shades and natural ventilation systems, and incorporating building materials that have higher capacity to absorb heat during the daytime.
The panel noted that the older houses and glass tower blocks prevalent in the UK were not designed for the extreme temperatures that we will be experiencing more frequently in coming decades. It will be critical to incorporate passive cooling strategies in new constructions and future design at system-wide and individual levels. These strategies could draw inspiration from parts of the world where managing the impact of high temperatures through passive cooling design choices is well-established and highly effective. Panellists emphasised that implementing passive cooling at scale is not a technological but rather a political and financial challenge.
For existing buildings, reliance on active cooling to address overheating would lead to spiralling energy demand and carbon emissions. Retrofitting older buildings - for example, installing external shades and awnings - can be effective. Innovative technological solutions have been developed, for instance wax-based phase-change materials which can be incorporated into ceiling tiles and wallboards, absorbing heat during the day and solidifying at night. The efficacy of simple behavioural changes, such as opening windows at night to enable ventilation, was emphasised.
However, the importance of understanding the limitations of these approaches was also acknowledged - technological solutions may be expensive or inaccessible, and behavioural changes may be difficult in urban areas where noise and air pollution are a problem. Further research to understand behavioural choices and interaction of building occupants with passive cooling systems was identified as a key pathway that could enable greater uptake.
The panellists participating in this event were Dr Shaun Fitzgerald OBE FREng, Director of the Centre for Climate Repair at Cambridge and co-founder of Breathing Buildings, Dr Rosa Schiano-Phan, Reader in Architecture and Environmental Design at the School of Architecture and Cities of the University of Westminster, and Dr Joel Gustafsson, founder of JG Consulting. The event was organised and chaired by Dr Monika Kreitmair, Postdoctoral Research Associate at the Department of Engineering and Cambridge Zero David MacKay Research Associate at Darwin College, University of Cambridge. Recordings from the Cambridge Zero Climate Change Festival are available to watch online here.