Cooling, a blind spot in UK energy policy
By Mehri Khosravi and Richard Lowes, Energy Policy Group, 25th March 2022.
The context
The cooling of buildings accounts for about 20% of the total current electricity use worldwide, however, it is estimated that the electricity used for cooling will more than triple by 2050 due to a changing climate and increased demands for comfort. Global energy demand for cooling may match that of heating by 2060 [1]. In addition, increased home working and changes in lifestyle may need to be considered when making cooling demand projections [2]. Cooling is critical for human wellbeing as it provides thermally comfortable indoor space, protects health, and increases productivity. However, most energy studies focus on indoor heating, and little attention has been paid to the growing energy demand for cooling [3,4]. The Executive Director of International Energy Agency (IEA) believes: ‘Growing demand for air conditioners (ACs) is one of the most critical blind spots in today’s energy debate’.
Cooling is hotting up
Current cooling demand in the UK is nearly 10% of total UK electricity demand [1]. Yet, the current demand for space cooling in buildings is small, estimated at 3% of the total final fuel consumption in 2016 [5]. However, it’s likely tht the UK’s cooling demand will increase due to rising temperatures [6]. The latest analysis of the UK climate, State of the UK Climate 2020, published in the Royal ‘International Journal of Climatology’, has shown that global warming is already being felt across the UK. The recent decade (2011–2020) has been on average 0.5°C warmer than the 1981–2010 average and 1.1°C warmer than 1961–1990. Heatwaves, like that of summer 2018, are now 30 times more likely to happen due to climate change [7]. Therefore, alongside average increases, summer temperatures will rise, as well as the frequency of heatwaves.
Current cooling demand in the UK is dominated by non-domestic buildings (compared to domestic sector). Approximately 6,187GWh of UK energy was consumed for cooling in 2019, mostly for non-domestic buildings (8). As figure 1 shows, the office sector has the largest cooling demand which accounts for around half of non-domestic energy consumption in the UK. Although the current demand for cooling is dominated by non-domestic buildings [8], National Grid has estimated likely uptake of ACs in the UK domestic sector to be 18 million units by 2050, compared to less than one million today (National Grid, 2018). They estimate that this would add 19-39 GW of peak electricity demand on a typical August weekend day compared to electricity demand today [9].
Figure 3: UK Cooling energy consumption by sector for non-domestic buildings ,2019 [8]
Cooling is lacking from current UK policy debates
Our review of cooling demand in UK energy policy shows that it has been underrepresented compared to heating, despite potential health implications associated with oveheating, which is one of the top risks in all UK climate risk assessments published to date. Here, we look at UK energy policy for cooling against the main cooling issues that we need to consider for cooling decarbonisation:
- Reducing the cooling demand through scaling up passive cooling strategies:
Following the CCC’s report on making UK housing fit for future (2019) and recommendations on the reviews of building standards by MHCLG, the Future Buildings Standard consultation proposed passive cooling strategies (such as insulation, window shading, ventilation and so on) in new residential buildings [1; 11]. This has now been considered by the Heat and Building Strategy to tackle the risk of overheating [10]. However, the scope of the overheating requirement is for new residential buildings and does not cover existing buildings [1]. The Heat and Building Strategy has been criticising by some professions as they state the strategy has overlooked the future cooling demand [12] and the proposed means to address overheating within the standard are too basic and still lack a clear plan to retrofit existing homes [13].
- Increasing the efficiency of cooling equipment:
In parallel with increasing passive cooling strategies to reduce the cooling demand, actual cooling should be meet through energy efficient equipment to reduce overall energy demand increases to support meeting the net zero target. The International Energy Agency estimates that most of ACs units sold around the world have energy efficiencies less than half of the highest achievable [14]. While highly efficient AC units are available on the market, most users purchase models that are two to three times less efficient [15], mainly because more efficient ACs often have higher up-front end-user costs [1].
Another aspect of efficiency concerns combining heating and cooling systems, such as using reversible heat pumps, a key low carbon heating option as recommended by various sources. Reversible heat pumps are one of the most effective cooling technologies available to decarbonise buildings that could deliver the heating and cooling of the buildings in a single system. According to BEIS (2021), Government interventions that encourage the uptake of air to air (ATA) heat pumps to decarbonise heating will also accelerate the uptake of cooling. However, in the UK, the air to water heat pumps is the dominant type of heat pumps in the market as ATA heat pumps require a warm air circulation system to distribute heat, but most houses in the UK have wet central heating systems [16]. In addition, system design and installation of reversible operation is key to delivering intended efficiency benefits and the UK skills base to do so is currently lacking [1]. Also, BEIS (2021) believes that the current public awareness of ATA heat pumps for providing heating is very low and hence there hasn’t been a large uptake of heating led cooling installations.
- Decreasing Ultra-low global warming potential (GWP) refrigerants and phasing down hydrofluorocarbons (HFCs)
F- gas use is the third impact area to manage in cooling as most emissions come from the cooling sector, comprising refrigeration, air conditioning and heat pumps [17]. HFC use is being phased down internationally under the UN Montreal Protocol with its Kigali amendment (2016) and regionally through the EU F-Gas regulation. The 2014 EU F-Gas regulation came into force in the UK in January 2015. The F-Gas regulations were retained in UK legislation post-Brexit which requires a 79% reduction in the use of hydrofluorocarbons (HFCs), which are the main group of F gases and are potent greenhouse gases, between 2015 and 2030 [18]. Under the F-Gas Regulation, the UK has already phased out more than 40% of HFCs consumption. However, most AC devices and heat pumps still rely on F-gases as their refrigerant in the UK [1]. Although, upcoming bans under the Great Britain F-gas Regulation have been introduced, it seems some more restrictions and even penalties are needed to phase out the F-gases.
Transitioning to net zero, heat and cooling decarbonisation will require significant increases in electricity generation and thermal energy storage to enable renewable electricity to supply cooling and heating [19]. Despite recognition of the need to develop thermal storage, the UK lags far behind other northern and central European countries [20]. Evidence shows there has been relatively little focus on the potential role of thermal energy storage to support decarbonisation of the UK energy system [21].
Conclusions
To sum up, the decarbonisation of cooling, as it grows, alongside heating decarbonisation are inevitable for meeting net-zero targets. However, with the expected growth in cooling demand and uptake of ACs, focusing only on research and policy towards affordable heating solutions, and neglecting cooling is strange, particularly when it is expected that many buildings will be increasingly electrified with heat pumps which could also provide cooling.
Hence, it is time to investigate the future cooling demand, impacts of the cooling demand on electricity infrastructure and how this could link to demand change associated with heat decarbonisation with considering social, technical, and institutional factors. Therefore, our new £1.1m interdisciplinary project ‘Flexibility from Cooling and Storage’ funded by the EPSRC has been designed to understand cooling demand considering technical and socio-economic factors, quantifying the impacts of increased cooling demand on electricity networks, and investigating the flexibility provision to the electrical power system from integrating cooling technologies and storage. By the end of this project, we hope that what is currently a blind spot in policy, will be a electrifying new topic which can support UK goals for climate and energy.
References
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