By Jenny Crawley, Stephanie Ogunrin, Shivani Taneja, Inna Vorushlyo and Xinfang Wang
In this report we summarise the findings from our project delivered as part of the Whole Systems Networking Fund.
Climate change has caused rising temperatures worldwide, including hotter summers in the UK, and in years to come households may be expected to start installing air conditioning. Currently, most UK building decarbonisation research focuses on creating sustainable and affordable heating solutions, neglecting cooling altogether. Notable unknowns are: an informed estimate of the prevalence of air conditioning, and the associated energy and CO2 impacts.
This project aimed to provide a first estimate of the effect of uptake of domestic air conditioning on the national grid in 2050. We then considered how this maps onto current/predicted electricity demand and availability of renewable generation.
Our approach was threefold:
Our scenarios resulted in 5-32% of English households adopting air conditioning by 2050. This range is lower than previous estimates based on simpler assumptions.
When added to the National Grid ‘Two Degrees’ 2050 scenario, our worst-case uptake scenario – in which 32% of households install air conditioning – increases the summer peak load by 7GW. Its effect is predominantly in the evening.
Figure 1. Summer day – GB electricity demand with and without domestic air conditioning.
Without air conditioning, the Two Degrees scenario predicts an evening peak largely caused by transport electricity demand. Air conditioning demand is expected to occur at the same time as this, and therefore AC exacerbates the existing evening peak.
Air conditioning demand is also not coincident with solar PV generation, instead occurring later in the day.
The results highlight a renewable energy availability problem, in that air conditioning demand is offset from solar PV generation by several hours.
This result is more meaningful when put in the context of other demands on the grid at the same time. AC and electric vehicles are currently competing for limited renewable electricity at the same time. This leads to a question of which demand is easier to shift out of the evening peak. Electric vehicles are likely to facilitate this more easily, although research is needed into what can be done to shift air conditioning demand forward so it can better utilise solar power.
On the plus side, it appears unlikely that air conditioning will create a problem for the capacity of the national and local electricity grid. This is because if heat is electrified, the winter evening peak will exceed the summer peak predicted in this study by up to a factor of two.
This project relied heavily on modelling due to a lack of real data on how air conditioning is used in British homes. Future research needs to tackle these evidence gaps and refine the assumptions made in this study around timing, load size, and demand diversity of cooling use.