Jun 8, 2021

Overheating risk and the impact of cooling demand

While there has been a focus on reducing energy demand for heating, with global temperatures set to increase, there has been little consideration for future for cooling systems demand.

There is no doubt that in recent years, the UK has experienced record breaking dry and sunny periods, and other notable summer heatwaves. 2020 was the UK’s third warmest and eighth sunniest year in UK national series [1].

UK Parliament recently released a POSTnote addressing the potential issues with increased temperatures and the demand for cooling in buildings, industrial processes and supply chains. To mitigate and adapt to the impacts of climate change, there will be a requirement for sustainable cooling solutions.  Addressing this issue now is important for preparing for the future, avoiding error and lag for solutions, providing affordable and accessible solutions.

The risks of overheating, particularly to UK dwellings and public buildings, is currently not well quantified. Overheating risks are difficult to predict and are dependent on various factors such as building types or being located in an urban heat island. The POSTnote indicates that around 20% of homes in the UK currently overheat, even in mild summers, and note an increase in heat related hospitalisation, illness, and deaths.

Not only is demand for cooling expected to increase globally, but there are also a number of issues with conventional cooling systems. Potential contributions to climate change include the need for electricity to support cooling systems, contributing to carbon emissions, and the use of fluorinated gases, potent greenhouse gases if they leak. Energy demand for cooling may compare to that of heating- with global demand for space cooling alone expected to triple by 2050. At present, residential cooling is the largest source of total global demand for cooling.

Space cooling will require a number of passive cooling strategies and behavioural changes or by actively sourcing, storing and distributing cold thermal energy.

PASSIVE techniques may include:
  • Carefully considered building design- addressing glazing, ventilation, light external surfaces, orientation
  • Green infrastructure- reduce the effect of artificial surfaces (that retain heat during the day and slowly release it at night), minimise the urban heat island impacts through the increase of urban greening. Additional benefits extend beyond air cooling measures.
  • Occupant behaviour- looser clothing, opening windows and internal doors, smarter control systems.
ACTIVE techniques may include:

Active cooling approaches require the use of an energy input. Often these use a refrigerant that circulates in a closed system.

  • Air conditioning (ACs)
  • Lower GHG technologies include: heat pumps, ground-source systems
How to make cooling strategies sustainable?

While aims to mitigate the risk of overheating are detailed in the National Planning Policy Framework, current policy in the UK is absent of specific sustainable cooling policies.

It is suggested that:

  1. Minimum energy efficiency standards be raised for AC devices. Increasing energy efficiency standards also relies on better operation and maintenance.
  2. A new business model be introduced addressing a circular economy approach- e.g. an end-user pays a specialist provider an ongoing fee to install, run, maintain and decommission its cooling system, ‘cooling as a service’.
  3. Heating and cooling systems are combined through heat pump installation, improving technical and cost efficacy.
  4. Promoting passive cooling techniques for buildings- most homes are becoming more energy efficient as a result of decarbonisation targets for heat, but considerations need to be made for cooling in summer.

 

At SHIFT we address the resilience of housing stock to expected future climate changes. As well as considering flood risk, we have developed bespoke tools for quantifying water stress and overheating risk in social housing stock. Take a look at our SHIFT Sustainability Standard for more sustainable measures for your housing stock.

Find the full POSTnote here.

[1] https://www.carbonbrief.org/met-office-a-review-of-the-uks-climate-in-2020