Risky business

Under the 2008 Climate Change Act, the government must publish an environmental risk assessment every five years. Hywel Davies reports

The UK Climate Change Risk Assessment 2017 (CCRA), published in January,1 recognises the trend towards warmer winters, hotter summers and changing rainfall patterns. It considers how this affects communities across the UK, and sets out ongoing investment and work to tackle these risks.

Based primarily on the independent evidence report, published in July 2016 by the Committee on Climate Change’s Adaptation Subcommittee (ASC), the report outlines the government’s ‘ongoing commitment to ensure the country can adapt to a changing climate’.

The ASC’s 168-page chapter on people and the built environment2 covers four primary policy areas: communities, buildings, the health and social care system, and population health and health protection. It notes the complex interaction between risks and the responsibilities of government departments – health protection falling to the Department for Environment, Food and Rural Affairs and the Department of Health; while buildings, communities and settlements are the remit of Communities and Local Government.

The CCRA also observes that many climate hazards have implications across several policy areas. Four major extreme-weather risks are identified: heatwaves, floods, drought and cold. Each has the potential to have an impact on communities, buildings, health and social care, and on population health. For buildings, extreme weather is likely to result in overheating, flood damage, damp and mould, subsidence and cold homes, as well as stressing and disrupting health services and – in the case of drought – water supplies.

CIBSE has produced new guidance on assessing overheating risk in homes,3 which has been a growing concern in the residential sector for at least a decade.

The CCRA is clear that concerns will continue to grow, with the supporting evidence review identifying overheating and the urban heat island as two of five key risks in the built environment. The heat island effect in urban centres will exacerbate increases in temperature.

Specialist buildings will need to be adapted to remain fit for purpose

Overheating also affects schools, hospitals, care homes, prisons, and other building types, with adverse impacts on health and thermal comfort. The proportion of dwellings that will overheat is very likely to increase with climate change, so consideration must be given to reducing the burden of overheating in existing buildings. Evidence of cost-effective adaptation of individual houses exists, but scaling-up to change the wider housing stock is complex, and guidance is needed on refurbishment approaches. 

Mitigation and adaptation measures should be combined when considering refurbishment projects and the wider implications of proposed improvements on the overall performance of the building.

The review suggests that, compared to older buildings, newly built hospitals are more at risk of overheating during hot spells because they do not have the same thermal mass, and because they are built as one large block, rather than several units.

Information from care homes suggests they may also be at risk from high temperatures because of building design and management issues. As the risk of overheating is likely to increase, these specialist buildings will need to be adapted to remain fit for purpose.

The evidence review says ‘the risk of overheating of buildings requires urgent action’, with energy demand for cooling buildings projected to increase – possibly exceeding £1bn – by 2050.

In homes, that cost falls on the occupiers, but for hospitals, care homes and schools, the costs of mitigation measures and of the consequences of overheating are borne by various government departments – and negative outcomes affect patients, pupils and residents.

The review also projects an increase in flood risk, with damages rising from £1.3bn in 2016 to £2.1-£12bn by the 2080s. Again, mitigating this risk needs to be considered alongside other building adaptations and improvements, to deliver the best and most appropriate outcomes.

The CCRA will now be followed by the second National Adaptation Programme, to be published in 2018, which will set out how the government intends to address these risks.

As the 2017 report demonstrates, the risks associated with extreme events requires a broader view – embracing several policy areas – if they are to be tackled effectively. An appropriate response to extreme events requires a coordinated and systematic multidisciplinary and multiple-agency approach.

If we are to shape our built environment in response to emerging evidence of risks and evolving needs, engineers have a very significant contribution to make.


  1. UK Climate Change Risk Assessment 2017.
  2. People and the built environment.
  3. CIBSE TM59 Design methodology for the assessment of overheating risk in homes, April 2017.
  • Dr Hywel Davies is technical director at CIBSE