Learnings

Outcomes

The air source heat pumps installed under this project were integrated with thermal storage units to maximise the functionality and efficiency of the system. This integration provided a considerable degree of flexibility in how electricity was used for heating requirements. Furthermore, the project incorporated smart grid controls alongside sophisticated smart heating management tools. These technologies were deployed to showcase viable solutions through a bespoke Direct Load Control (DLC) system and a tailored Home Energy Management System (HEMS). The combined functionality of these systems was designed not only to accelerate the adoption of low-carbon electrified heating systems but also to reduce the overall strain on the electricity network.                       

Summary outcomes:

• The trial successfully demonstrated the technical viability of the complex arrangement described above. 
• The system worked; demand reduction was provided when requested and customer comfort was maintained.       

Lessons Learnt

1.      Recruiting participant interest:

The E.ON Digital Marketing (DM) targeting channel stands out as the dominant source of referrals, contributing 462 applications, which accounts for 73.7% of the total. This is a clear indicator that EON's targeted campaigns are by far the most effective at generating interest.

The Social media activity supported all channels and played a vital role in compounding the visibility and awareness of the project and the offer. Our analysis showed that whilst people interacted with the social media posts, the catalyst for applying was the letter they received via post. This insight led to driving more channel activity to the targeted mail drop approach. 

2.      The most common reasons for participant cancellation were:

                                      i.          Customer not eligible (22.4%)

                                    ii.          Current heating does not qualify (17.5%)

                                   iii.          Property type unsuitable (21.1%)

                                   iv.          Too much disruption (2.4%)     

3.      Recommendations for improving participant retention / reducing cancellations:

• Clearer communication of eligibility / prequalification criteria to reduce the instances of applications from ineligible candidates.
• A comprehensive review of local planning regulations and permitted development rights related to heat pump installations, prior to targeting specific building archetypes. (Whilst not insurmountable, mid-terrace properties faced distinct obstacles that hindered their suitability to participate).
• Customers to be provided with realistic expectations at the Energy Expert Call and Survey stages about potential disruption, installation timelines, and how their experience will be managed.

4.      Innovative solutions to space constraints

The installation phase of the project faced several space constraint-related challenges that impacted its pace. 

• One of the main issues was understanding the spatial requirements needed to house the heat battery and DLC hot water cylinder technology, which slowed progress. In response to this challenge, innovative solutions were successfully implemented to simplify the installation process. One such solution was a pre-wired, self-contained casing that was well-received by installers.
• Another solution that was explored to overcome spatial limitations was the possibility of constructing dedicated outbuildings. This solution offered a way to house the equipment in a purpose-built structure, ensuring that the heat pumps could function efficiently without compromising space within the home or creating aesthetic or functional challenges in the surrounding environment. While this approach ultimately exceeded the initial project funding budget, it proved to be a promising strategy. With more time and resources allocated to developing this solution, it has the potential to greatly reduce the disruption homeowners face when transitioning to heat pump systems, providing a more seamless and effective integration of renewable energy technology into their homes.

5.      Supply chain resilience

It’s important to avoid reliance upon a single installation contractor as this exposes the project to a greater risk of delay if something goes wrong. The limited availability of trained insulation installers posed a big challenge to the project.

6.      Importance of Local Authority Support

Local authorities played a critical role in the deployment of innovative low-carbon technologies. Their support allowed the project to:

• Mobilise funding: Ensure HEEPS ABS and ECO4 along with other local grant schemes are accessible to eligible households.
• Build trust: Facilitate outreach efforts, leveraging existing local networks to overcome scepticism.
• Address barriers: logistical challenges (e.g., installation difficulties) and find practical solutions for communities.
• Coordinate efforts: Align initiatives with regional decarbonisation and climate action plans, ensuring broad community benefits. This was more effective in the Highlands region.

7.      Role of the Distribution Network Operator (DNO)

The relationship with the Distribution Network Operator (DNO) played a crucial role in the successful delivery of the project. Regular meetings were held with the operational DNO Connection teams, fostering open communication, and the sharing of delivery plans created a far smoother and more transparent journey throughout the project lifecycle towards the end of the project. The ability of the DNO to anticipate and address potential bottlenecks before they arose was essential to achieving the project timeline. This proactive approach and open dialogue enabled the teams to overcome some complexities of network upgrades effectively and efficiently. The collaborative approach was essential in overcoming hurdles and ensuring project successes.        

8.      Customer satisfaction

Although customers had reduced control, high participant acceptability was reported, which was primarily attributed to the following factors:

• the comfort override mechanism which had been explained to participants provided a perception of “control being available when needed” providing peace of mind.
• the contractual relationship between the customer and E.ON provided trust that there were available routes to manage dissatisfaction, technical issues, system maintenance & servicing and critically that E.ON, as the energy supplier and solution provider would take on the responsibility for onward engagement and co-ordination with the DNO.
• Reducing the level of psychological demand on customers. The level of automated control made it easy and low effort for consumers to participate in the trial. Their only decisions were in relation to setting their heating schedule (a familiar action within their capability and knowledge). There was no decision fatigue that we’ve experienced in other flex trials, associated with having to make active and repeated decisions to “opt in” to participate in constraint / load shifting events. Equally it removed the complexity and uncertainty associated to making active decisions on “how or when to load shift” and as seen in the research below concerns over “doing it right” and any unintended consequences relating to cost. 

9.      Interoperability & connectivity

A strong Long Term Evolution (LTE) signal is crucial for maintaining connectivity with the cloud platform, which monitors the ongoing reliability and continuous operation of the devices. 

The ReHeat trial experienced disruptions to data collection / active monitoring as a result of loss of LTE signal strength. This impacted the volume of data available from specific properties.

10.   Post trial customer value stream

Customers in the ReHeat trial were not remunerated for their participation in constraint / load shifting events. Instead they were supported via various funding streams to upgrade their heating system, enabling energy efficiency improvements (HEEPS:ABS) and to extend this solution with the thermal store, HEMS and DLC (funded via NIA). 
For the defined trial period this was sufficient for customers to participate and feel like they had realised cost savings and value. However, the delivery of consistent, ongoing value was a reported limitation across c.50% of trialists based on customer feedback as we exit the trial period.
Customers have specifically queried how they will maximise cost savings from the use of the thermal store post-trial. Our trialists were reporting increased awareness of the availability of off-peak tariffs, the ability to “charge overnight” and capture the value of lower electricity prices. 
However, a limitation of ReHeat and our designed DNO led control, is that the constraint periods could occur at varying times of day depending on local constraint factors and impact the necessary charging frequency and charging timing of the thermal store. The charging schedule was variable and as such we did not pre-determine overnight charging. Instead, we let the HEMS deliver a charging schedule relevant to maximising opportunity to deliver each load shifting request. 
This introduced complexity for customers in not knowing which tariff they should chose, would this inadvertently cost them more if they picked a multi-rate on / off peak tariff and a feeling of missing out on value that should be available to them going forward. A consideration could be to instead reward customers via cashback/fixed payment to ensure their continued participation and a fair, tangible value realised. 
Therefore, ongoing business models between customer, energy supplier and/or aggregator and the DNO could be considered to ensure the value streams are clearly defined. Particularly important where the DNO wants to exercise high levels of control and automation (as executed in Reheat) of behind the meter assets long term and manage consumer protection appropriately.