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?

External shading – shutters and awnings that shade windows from sun in hot weather. Fixed solutions that are designed into homes are ideal, but encouraging retrofit of shades, and expanding the availability of temporary shades that can be put up for a few days without planning permission.
Generous openable windows free from barriers to opening them. Barriers to opening windows tend to be primarily noise and security risks, so planning for residential areas to be quiet at night and not building new homes in noisy areas, ensuring window manufacturers provide a range of elegant and secure openings including grilles and shutters that enable ‘easily accessible’ windows to be left open when homes are occupied whilst still allowing inhabitants to feel safe. Architects are reticent to design in bars over windows, but these are often retrofitted by city-dwellers living in ground floor flats so many inhabitants do see the benefit.
Fans – any time of fan is helpful in hot weather as it provides a breeze and adiabatic cooling as the evaporation of sweat from our bodies increases. Installed ceiling fans are ideal and particularly valuable where cross-ventilation is not available.
Behaviour – recent heatwaves have increased public understanding on how to operate their homes in extremely hot weather. More people now close windows and curtains in the hottest parts of the day and open them in the evenings when it’s cooler during a heatwave event.
Most UK heatwaves last only a few days so simple, cost-effective passive measures are much more appropriate than more energy intensive options.

Does the current planning framework do enough to encourage heat resilience measures such as cooling shelters, water bodies, green infrastructure and shading to be integrated into urban planning? Where such measures are incorporated, how accessible and successful are they?

Shading is pivotal in mitigating against overheating risk, and external shading is the most powerful in this respect. In my experience architects and planners have greatly varying attitudes to external shading features and other overheating mitigation measures. It would be great to see a more consistent approach, and new vernaculars developed, particularly for parts of the country with similar overheating risk e.g. greater London.

Gaining planning permission for external shading devices such as shutters or awnings can be difficult in some areas. Such devices are ubiquitous in warmer parts of the world and need to become so in warmer parts of the UK. Relaxing planning guidance to appreciate the benefits of effective external shading would be a helpful step.
Finding suppliers for a suitable range of external shading devices is also very difficult. Despite there being a wealth of options available on the continent, very few are readily available in volume within the UK. Ensuring supply chains have a range of products, potentially manufactured in the UK, that meet all the relevant safety standards, particularly for higher rise buildings, at reasonable cost would be a massive step forward.
Low technology, passive options are most likely to be effective as they are easily understood, have zero or low running costs, and are less likely to malfunction. Trees and water bodies rarely cause offence and have many other benefits to local communities beyond those in cooling the microclimate. External shutters, and fans are also easy to use and understand, especially once the benefits are explained.

The committee should also seek evidence from:

Andy Love at Shade the UK https://www.shadetheuk.com/
British Blinds and Shutter Association https://bbsa.org.uk/ – ask them to do more to make compliant external shading products more readily available in the UK

What can be done to protect the UK’s existing public and private sector housing stock from the impacts of extreme heat while ensuring that homes are sufficiently warm in the winter months?

There is no evidence to suggest that better insulated homes overheat more in summer provided that adequate openable windows are provided. Evidence Loughborough paper: ‘Dwelling and household characteristics’ influence on reported and measured summertime overheating: A glimpse of a mild climate in the 2050’s’ K.J. Lomas et Al.

See also GHA retrofit tool: https://kb.goodhomes.org.uk/tool/overheating-retrofit/ - This tool is intended for use at the early stages of residential retrofit projects, or on existing homes, in order to identify key factors contributing to overheating risk and possible mitigation measures. It is applicable to existing homes, retrofits, and conversions of non-domestic buildings to residential accommodation.

Reference Arup report ‘Addressing overheating risk in existing UK homes’ for CCC: https://www.theccc.org.uk/publication/addressing-overheating-risk-in-existing-uk-homes-arup/#:~:text=The%20Climate%20Change%20Committee%20(CCC,how%20much%20that%20might%20cost.

Does the Government’s Future Homes Standard adequately consider overheating in homes? If not, what additional elements should it include?

As we understand it, the government is not consulting on any changes to the FHS on how overheating in homes is considered. Part O was introduced into building regulations in the 2021 update. It is clunky and poorly worded so has led to significant confusion. See 4 Inkling blogs so far on this subject - https://www.inklingllp.com/?s=part+o.

CIBSE TM59 which is the modelling methodology on which the dynamic modelling route within Part O is based, is being updated this year. The updates will include the latest research on the effect of heat on sleep disturbance, and require assessment against future 2050 weather data based on the latest climate projections. The updated TM59 should be adopted into Part O with the FHS in 2025 at the latest.

The simplified method within Part O should also be simplified (to live up to its name) and have a ‘low risk’ geographical area defined that has less onerous requirements to allow homes built in the North East and other cooler parts of England not to have to adhere to the same overheating mitigation standards as homes built in warmer areas such as Reading.

The Future Buildings Standard should also be looking at overheating risk in non-domestic buildings. Part L currently includes Criterion 3 on limiting solar gains, but this is clumsy, produces some odd results at times (such as when rooms have very small areas of exposed wall), and doesn’t allow for alternate more sophisticated risk assessments to be used instead (such as CIBSE TM52). Alternatively, a cooling demand metric could be implemented. Criterion 3 is also not routinely complied with and this is not always picked up.

August 2023