Understanding What Homeowners Really Want and Need: User Research to Shape Retrofit Tools that Work
Case study: Consumer-Focused Net Zero Buildings Recommendations Tool
User research to shape the development of a digital Retrofit Recommendations Tool - a public-facing service to help UK homeowners identify suitable retrofit measures, understand costs and benefits, and access available funding.
Growth Guides were commissioned by City Science (as part of the Innovate UK-funded Net Zero Buildings programme)
The challenge
Retrofitting homes is a critical part of the UK’s net zero strategy. But it’s confusing, time-consuming and full of unknowns - especially for homeowners who don’t know where to start.
Previously, homeowners typically had to pay for an in-person assessment from a retrofit coordinator just to get a basic sense of what’s possible. That’s a big leap - especially for those who aren’t sure whether retrofit is even right for them, or who worry about being upsold or misinformed.
City Science’s idea was to create a digital tool that removed those early barriers. Something people could use instantly, with no commitment, to explore potential measures, understand likely costs and impacts, and see what support might be available. Something that could open the door to retrofit for households who might never otherwise take the first step.
But with such a broad and variable audience, the risk was clear: build something that ticks all the technical boxes, but gets ignored in the real world.
That’s where we came in...
Our Role
We designed and delivered a fast-paced, three-stage user research programme - structured like a sprint - to test, iterate and improve the tool at every step of development.
- We created the research structure and schedules for each stage, working closely with City Science to align on prototype priorities.
- We recruited a representative mix of UK homeowners and prospective homeowners, spanning ages, property types, retrofit experience and digital confidence.
- We ran in-depth moderated sessions using tool prototypes at each stage.
- After every round, we provided rapid-turnaround feedback - including user insights and specific, actionable recommendations.
- These insights directly shaped ongoing development, with tool improvements made between sessions and then re-tested in the next stage.
This iterative approach meant the tool evolved quickly, based on real-world wants and needs rather than assumptions.
Research stages & methodology
The research was split into three focused stages:
Stage 1: Testing the concept
Participants were shown an early prototype of the tool to gauge initial reactions. We explored their understanding of the purpose, their perception of the value, and their comfort level in sharing information.
Stage 2: Exploring changes and mobile use
We tested updated wireframes and designs, including a working mobile version. This round focused on usability, navigation and the framing of questions.
Stage 3: Testing the full user journey
In the final phase, we explored the complete journey from homepage to recommendations. We tested comprehension, credibility, data privacy concerns, and the perceived usefulness of the outputs.
Key Insights
The feedback we gathered helped shape the tool in meaningful ways. A few core insights stood out:
1. Trust is the starting point
Every user asked who was behind the tool - and how their data would be used. Government or council endorsement added credibility, but any hint of commercial interest created suspicion, especially if it wasn’t absolutely explicit. Trust had to be earned through clear, upfront communication and transparency.
2. People want control, not prescription
Users were turned off by tools that made assumptions or forced them down a single path. They wanted flexibility: to change inputs, tweak priorities, and explore options - even if those options were outside their budget.
3. Clarity beats perfection
A highly detailed report wasn’t the goal. Users wanted simple, personalised recommendations that were easy to act on. They valued clarity on what to do next, and what it might cost or save.
4. The perceived value has to be obvious
When asked why they would use the tool, participants wanted to see clear outputs - not vague suggestions. They wanted something tangible: a list, a quote, a next step. The tool’s value had to be visible within the first few interactions.
5. Brand signals matter
Logos, names and partnerships influenced how users felt - positively or negatively. Some wanted to see brands they recognised. Others were sceptical unless logos were clearly explained. Any inconsistency reduced trust.
Outcomes and impact
We produced detailed insight reports after each stage, identifying opportunities to improve the tool’s design, flow, content and framing.
Across the three stages:
- 14 participants completed in-depth testing across multiple rounds
- 90% said they would use the final iteration of the tool themselves
- 100% said they would recommend it to someone else
- Every participant said it would make it easier for people to consider or begin retrofit work
Our final report offered 15 detailed recommendations, including ways to:
- Frame language around data and privacy
- Improve navigation and mobile experience
- Strengthen perceived value and clarity of outputs
- Tailor the tool for different levels of retrofit knowledge
What this work shows
When it comes to retrofit, digital tools can play a huge role - but only if people trust them, understand them, and find them useful. That means designing with users, not just for them.
In this project, we helped City Science ensure their Retrofit Recommendations Tool wasn’t just technically sound - it was actually wanted, understood, and fit for purpose in the real world.
"I wish this was available when I started my journey. It would have been my first port of call."
Growth Guides delivers high-impact, user-driven communications, digital experiences and market research across the net zero space. We’ve worked on retrofit tools, community heat pump trials, and large-scale engagement strategies for local authorities, consortiums and startups alike.
Client Testimonial
"Working with the Growth Guides team, particularly Tony and Holly, has been a game-changer for our projects. Their expertise, unwavering reliability, and results-focused approach consistently drive our initiatives forward. They are highly revered within our team as true partners who go above and beyond to ensure success, making the entire process seamless and impactful.”
- Jade Baker-Edwards, Principal Energy & Sustainability Consultant, City Science