Previous research from Nesta, such as HeatFlex, has focused on whether demand can be shifted, in a manner acceptable to homeowners, using pre-heating ‘events’ . Modelling conducted during our work with Cornwall Insight has also shown that households with heat pumps could make significant savings by changing to a ‘time of use’ tariff. This project stands to bridge the gap between these two pieces of prior research and quantify the role that heat pump flexibility and innovative tariff design could have in heat pump affordability. The trial will be conducted over the winter of 2024, concluding in April 2025.

Currently, running costs are considered to be the second biggest barrier to heat pump adoption in the UK. We would theorise that if the tariff is appealing to customers and is commercially viable, the increase in consumer awareness (due to other work Nesta is doing) and the decrease in running costs could be a significant enabler for heat pump adoption.

The Demand Flexibility Service (DFS), introduced by National Grid ESO in 2022, rewards households for reducing electricity use at specified times. The energy system operator (ESO) has committed to further rounds of the DFS for the coming three winters, and for the first time suppliers will be able to ‘stack’ DFS payments with other services and incentives offered by distribution network operators (DNOs). This could increase the value of flexibility to consumers, further bringing down running costs.

Currently, the impact on efficiency (sCOP – a metric that measures how efficient a heat pump is over a heating season) from flexibly using a heat pump is poorly understood. This research presents an opportunity to measure sCOPs and assess whether drops in system efficiency (impacting utility bills) are offset by the value of a type-of-use tariff. Evidence of an acceptably minimal impact on sCOP could help persuade the heat installer community to be advocates, rather than sceptics, on heat flexibility. 

Participants will have their heat pumps controlled for a series of 2-4 hour events. These events will consist of a pre-heating period and a flexibility period where internal temperatures are kept within + or - 1℃ of their usual preferred temperature. Crucially, participants will not be pre-notified or asked to opt into these events as they have already signed up for this automation as part of the trial. If successful, the automated control should deliver a demand response without customers being aware, and therefore not experiencing any detriment or discomfort. 

We will be recording each participant’s home electricity use and their heat pump’s electricity consumption. Participants will be asked to complete weekly surveys to help us understand whether they have experienced any discomfort, or whether they noticed the events occurring at all. Alongside this, we will be inviting a portion of the participants to take part in interviews where we will gain a greater depth of insight into their experiences during events.