Low-Carbon Social Housing Retrofit and Overheating Risk: A Review

Date

2021-04-12

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Working Paper

Peer reviewed

No

Abstract

This report provides a review of the current state of knowledge on low-carbon retrofit of social housing, and how these retrofits may affect the risk of overheating in social housing properties post-retrofit. Overheating risk assessment is a growing area of concern in built environment research, and the drive for warmer homes in winter, and more energy efficient homes, has led to increasing levels of energy efficiency retrofits in the domestic sector. However, a lesser amount of work has been done to date on how these energy efficiency retrofits could increase the risk of properties overheating in warmer periods. This is particularly relevant considering the potential for warmer summers going forward in a future warming climate. A number of definitions are available at present for what constitutes overheating in a property. Accepted definitions from human thermal comfort research put the comfortable range of temperatures for human domestic occupation at between 19°C and 26°C, but surveys have shown that a number of different property construction types in different locations around the country exceed these temperatures on a semi-regular basis during warm periods. This is due to a wide array of factors, broadly categorised in this report as location-based risks, property-based risks, and occupancy-based risks. Location risks are associated with the physical environment of the property: factors such as local albedo, urban heat island effect and prevalent wind patterns are all location-based risks. Property-based risks involve the built form of the property and its design: the number of fabric elements, overall glazed area and orientation of the property are examples of property-based risks. Finally, occupancy-based risks are associated with how residents use the property: factors such as appliance use, window-opening regimes, the use of blinds and occupancy profiles are all occupancy-based risks. There are a range of technical and non-technical measures available to mitigate the risk of overheating in social housing. Technical measures should follow a hierarchy of passive through active, with focus being placed on zero- or low-energy measures first, then moving to more active solutions if passive solutions are not having sufficient effect. Passive measures include increasing passive heat rejection through window-opening, window tinting to prevent solar gains, and installation of external or internal shading. Active solutions include mechanical heat rejection (such as ventilation systems) or mechanical cooling (such as air conditioning systems). Behavioural measures should focus on how the user operates the home system, and put emphasis on proper methods for through-ventilation for heat rejection, window opening and closing regimes and time-shifting of heat-rejecting appliance use. This report recommends implementing a communications procedure through the Council website where social housing tenants can find advice on overheating and feed back about overheating they experience, and an assessment procedure for use in tenancy gaps and post-retrofit to assess properties for overheating risk.

Description

Keywords

energy efficiency, overheating, social housing, United Kingdom, Leicester, retrofit

Citation

Kerr, D.W., Reeves, A. (2021) Low-Carbon Social Housing Retrofit and Overheating Risk: A Review. Report submitted to Leicester City Council.

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Research Institute

Institute of Energy and Sustainable Development (IESD)