Dr Jing Zhao (University of West of England)                            HRSC0003

Written evidence submitted by Dr Jing Zhao (University of West of England)

Submission to the Environmental Audit Committee’s Inquiry into Heat resilience and sustainable cooling

1. Thank you for holding this very important and timely inquiry into heat resilience and sustainable cooling in the UK. I am a senior lecturer in Architecture, and a researcher in sustainable building standards, Net Zero policy and climate resilience and adaptation. This evidence submission addresses the following inquiry items:

• What evidence exists on the relationship between heat and human health (mortality and morbidity), and which communities are worst affected?
• How can sustainable cooling solutions and adaptation strategies be implemented in such a way as to minimise overheating, reduce energy consumption and prevent overloading of the electricity grid during peak demand?
• What actions can be taken to protect those most vulnerable to the impacts of extreme heat?

2. This evidence is based on two research projects that I undertook. The first research is my PhD thesis conducted from 2013 to 2017 with the University of Edinburgh. This research conducted case studies of residential Passivhaus[1] projects, focusing on the residents’ lived experience, behaviour and adaptation in controlling overheating, in relation to the design of Passivhaus dwellings.
3. The second research was commissioned by British Academy for the Net Zero Policy programme. This research identified critical policy gaps, barriers and transition risk factors in delivering Net Zero policies in Affordable Housing (AH) sector. Signposted evidence to the health and economic effect of overheating on vulnerable residents, and proposed a human-centred support and engagement framework.
4. The main evidences relevant to this inquiry from the two pieces of research are summarised below:

• Incorporating shading (external and internal), thermal mass, and effective cross-ventilation in design are essential in minimising overheating and reducing summertime energy use. This is especially true when buildings are designed to be more airtight. Employing efficient mechanical solutions such as Mechanical Ventilation and Heat Recovery system (MVHR) intelligently in summertime could also help to expel excessive heat. There isn’t enough experience and skills shared among the supply chain in how to minimise overheating risks in design.
• An increasingly prominent issue facing AH residents is summertime energy poverty. Social housing stock, which has a high proportion of flats, newer dwellings and buildings with higher EPC ratings, is more prone to be overheated. Rooms inhabited by vulnerable occupants were found to be more likely to overheat due to a lack of ventilation or where the ventilation control is limited by age or mobility. The financial constraints of AH residents also put them in higher risk of overheating.
• Most importantly, even in ultra low-carbon dwellings such as Passivhaus homes, residents play an important role in reducing overheating without incurring extra energy consumption. Behaviour adaptation has been crucial in controlling summertime overheating in studied cases (window and blinds opening, MVHR control, etc.). Most residents are capable and willing to change behaviours if given sufficient support.

5. The evidence suggests the following recommendations for action:

• Support the supply chain in design and construction. Invest in skills training targeting on overheating risks. Produce design and retrofitting guidance and contemporary case studies in addition to Approved Documents, showcasing contemporary projects in different UK regions that used ‘Fabric First’ approach[2] that achieved winter comfort, carbon reduction and minimised summertime overheating. Designing and retrofitting heat-resilient buildings could effectively reduce energy consumption and prevent overloading of the electricity grid during peak demand.
• Support the residents. Produce a policy framework that engages the residents in overheating adaptation and behaviour change. This should include accessible guidance from the central government and will be delivered by a local framework (local authorities, housing associations or charities) using a place-based approach. Where behaviour adaptation cannot be achieved because of age or mobility, an appropriate support framework in arranging vulnerable occupants to live in dwellings less affected by overheating risks should be in place.

6. The paper reporting on the first research can be found here: Do passive houses need passive people? Evaluating the active occupancy of Passivhaus homes in the United Kingdom. The second research paper is expected to be published in British Academy Journal later this year. Overall, I hope that the studies will contribute to a better understanding of heat resilience strategies in the UK.

July 2023