Strategic Marketing for a Scalable Retrofit Subscription Model: From Zero to 8,000 Sign-Ups in 5 Months
Case study: Energy Saver App
The Energy Saver App was a retrofit trial in Oxfordshire, offering solar and battery tech via a no-upfront-cost subscription. Growth Guides led on branding, marketing, and user research for clients Oxfordshire County Council and SMS to drive over 8,000 sign-ups within 5 months and validate one of the UK’s most successful retrofit projects ever.
The Challenge
To meet net zero targets, the UK needs mass adoption of home energy tech like solar panels, batteries, and heat pumps. But most homeowners face cost barriers, technical complexity, and confusion about where to begin.
The Energy Saver App project aimed to prove that there's a better way. Backed by the Department for Energy Security and Net Zero (DESNZ), the trial introduced:
- An app-first model that gave users insight into their energy usage via smart meter data
- A subscription-based retrofit package - solar panels, batteries and optimisation - with no upfront cost
- A local authority-led approach, designed to increase trust and legitimacy among residents
The principle: meet people where they are. Start with helpful insights, then introduce retrofit tech as the logical next step - managed through one simple, intelligent, and trustworthy service.
Our Role
Growth Guides were initially brought in to deliver an advertising campaign for the Energy Saver App. But when the project began, there was no brand, no name, and no website in place. It quickly became clear that these fundamental components would need to be created from scratch - and fast.
A core part of how we work is identifying what’s most important to get right, especially where something is both missing and mission-critical. As the work unfolded, we naturally stepped into the areas where we were most needed.
This meant creating the brand identity, building and maintaining the website, leading all user research and conversion optimisation, and helping shape the wider communication and product strategy. Our role evolved significantly because the project required it - and because we were committed to making it succeed.
Audience Segmentation & Persona Development
Before we named the app or wrote a single line of copy, we set out to understand who we needed to engage, and what would motivate them to act.
Our segmentation work analysed the total addressable market across Oxfordshire, with a focus on households with smart meters. Drawing on national attitudinal data, local demographic insights and sector trends, we explored:
- Motivation hierarchies around saving energy vs climate concern
- Sub-segment differences by generation and household type
- The scale and relevance of behaviourally receptive audiences
We identified a large majority (84%) who were open to energy-saving messages, typically prioritising financial savings with environmental benefits as a secondary motivator. This informed a broad campaign focus - while allowing us to define actionable sub-segments, and six core personas.
Naming, Branding & Concept Testing
Informed by our segmentation work, we developed a shortlist of potential names and visual identities. From the outset, we treated this as an iterative, user-led process - with creative development and testing running in parallel.
- Multiple brand names were tested for clarity, appeal, and credibility
- Visual identities and logo options were tested with real users to gauge trust and comprehension
- Feedback was used to refine the shortlist and guide the final creative direction
The chosen name - Energy Saver App - was deliberately simple, clear, and accessible. It did what it said on the tin, which was essential for a brand seeking rapid awareness and trust at scale.
The final brand identity:
- Was visually distinct yet neutral enough for a public sector-led initiative
- Was recognisable, flexible and easy to implement across media
- Was later adapted to align with SMS’s Metis framework, without losing its independent clarity
Website
While the website was originally outside the project scope, it quickly became a mission-critical tool. It served as the central source of truth for all audiences - residents, stakeholders, media, and partners.
We:
- Designed, wrote and launched the website under intense time pressure
- Used it to communicate the app's purpose, benefits, and data privacy in plain English
- Actively updated the site throughout the project as the solar and battery offer evolved
- Created a structured, user-friendly experience that reflected key persona needs
In practice, the website became the anchor point for the entire project’s communication strategy. It offered clarity in a space where residents are often overwhelmed by complexity.
Campaign Strategy, Creative Development & Rollout
With the clock ticking and campaign space already being booked before the brand and site were finalised, we had to work fast and flexibly. Our role evolved into leading the full communications strategy across multiple channels and phases.
We delivered:
- A detailed rollout plan and budget, with resource split across channels and built-in review points
- Direct mail and leaflet drops targeted by postcode
- Bus ads across key local routes
- UGC-style video content to explain the offer and build social proof
- Targeted local radio, social and digital campaigns
- Poster and out-of-home placements
- PR and media support, including BBC and local press coverage
- Organic and paid social campaigns tailored to our audience segments
Quantitative Research (Awareness Tracking)
We commissioned three waves of surveys with Oxfordshire residents (August, October, March), tracking:
- App awareness and campaign recall
- Feature appeal and likelihood to download
- Interest in subscription-based retrofit offers
Key findings:
- Awareness reached 43% of the population in March 2015 - less than a year after launch
- 88% said they were likely to download the app
- 76% were open to a subscription retrofit model if it saved money
Qualitative Research (Fixing Conversion Friction)
Early success in driving downloads was followed by a sharp drop in conversion: fewer than 25% of users successfully connected their smart meter.
We designed a deep-dive qualitative programme to uncover and fix onboarding friction. We conducted:
- 14 pre-launch interviews exploring message clarity and initial impressions
- 8 guided user walk-throughs of the registration and connection process
- 7 follow-up interviews to test revised flows and language
- We also reviewed 100+ anonymised user sessions using behavioural tracking tools.
Key insights:
- Registration language was overly technical and created mistrust
- App copy assumed prior knowledge and missed key benefit communication
- The multi-screen process confused users and caused drop-off
Actions taken:
- Delivered 17 detailed UX recommendations, including copy, flow and layout changes
- Supplied annotated mock-ups and worked directly with implementation partners
- Saw a significant uplift in smart meter connections post-implementation
Outcomes & Impact
As shared by SMS’s Tom Woolley:
“One of the best partnership projects I’ve been involved in!”
✅ 7,500+ users engaged with the Energy Saver App
✅ Smart meter data enabled tailored insights for every user
✅ PV + battery simulations run for thousands of households
✅ Achieved 65%+ conversion from interest to install intent
✅ Validated the local authority-led subscription model as scalable and desirable
The retrofit offer was so well received that the trial reached capacity ahead of schedule.
Client Testimonial
“Growth Guides have been fantastic to work with across multiple retrofit projects. You get personalised, flexible, professional and friendly support from Tony, Holly and the team. They’re great at parachuting in to make timely improvements based on real-world trial and testing, so you can be sure of a successful outcome.”
— Dale Hoyland, Retrofit Team Leader, Climate Action Service, Oxfordshire County Council