WIREDGOV

This month we have been exploring the topic of climate science for decision making. The UK Government’s Net Zero Strategy includes commitments related to how we decarbonise our energy supply and how we power buildings in light of our changing climate. In this blog post we explore the value of weather and climate science in achieving these commitments.

Air source heat pumps are widely tipped to be a significant part of the heating energy mix in future. Picture: Adobe Stock.

Reducing our reliance on fossil fuels to heat and power homes and buildings is critical as we strive to mitigate against the worst impacts of our changing climate. When choosing the most appropriate alternatives, there are many factors to consider such as cost, suitability for retrofitting and performance.

At the Met Office, we have been undertaking research to improve understanding of the impact of cold-weather events upon energy demand if heat pumps play a significant role in decarbonising heating.

The electrification of heating would significantly increase the sensitivity of energy demand to temperature, particularly during periods of cold weather where heating demand is high.

If heat pumps are installed widely, the overall electricity demand could reduce on cold days compared to a highly-electrified energy system without heat pumps. Recent performance data analysis indicates that air source heat pump performance has improved over the past seven years. However, their efficiency decreases as external temperature decreases. So it is important to understand the impact of extreme cold weather events on electricity demand in a scenario with high heat pump installation.

Cold weather events

Using a sample area of central England, we have explored the daily minimum temperatures associated with cold-weather events of different return periods in current and future climates. The return period of an event is linked to its frequency, with an event with a return period of 20 years (a 1-in-20-year event) expected to occur once in that time. For example, we found that for this area and in today’s climate, a cold-weather event with a daily minimum temperature of -10.5 °C is a 1-in-20-year event.

The temperature associated with extreme cold events in 2050 will depend on the level of global greenhouse gas emissions in coming years. In a low-emission scenario we could expect a 1-in-20-year event in 2050 to be associated with a minimum temperature of -8.4 °C.

Met Office scientist Isabel Rushby explains: “Our analysis provided updated temperature values to be used in modelling around heat pumps, including an expected 1-in-20-year cold-weather event in today’s climate and in 2050, considering a range of emissions scenarios. We’ve also analysed hourly temperatures during these events to help answer questions about within-day temperature variability. This is important to consider as electricity demand can vary greatly depending on the time of day.”

Energy demand and generation

Our next step will be to further characterise weather events that may place stress on the future energy system in terms of energy demand and generation, including how these weather events may look in the future with climate change. This will allow us to provide, for example, context around expected wind speeds and how this relates to renewable energy generation when a 1-in-20-year cold-weather event occurs.