Problem: cold homes and one-off quotes
On Rowan Street in Bananzia, 38 terraced homes faced the same practical problem: aging gas boilers, limited off-street parking, and no reliable way to compare heat-pump quotes. A volunteer survey in spring found 22 homes at EPC D or lower, 11 with single-glazed rear windows, and only six households that had received more than one installer quote. The street had urgency, but not a shared plan.
- Three quotes for similar three-bedroom homes ranged from £9,800 to £12,900.
- Scaffolding was booked separately for adjacent properties on the same week.
- Two residents were unsure whether radiator upgrades were included.
Cause: bespoke pricing without shared information
Each installer priced the job alone, so travel, scaffolding, and commissioning were repeated. Householders had no common scope, which made comparison difficult and pushed uncertainty into contingency lines. The bananzia advice line turned those isolated quotes into an anonymised dataset: cost per kilowatt, radiator counts, insulation notes, and lead times. The pattern was clear: the work was not too expensive in every case; the buying process was fragmented.
That fragmentation had a second cost. Without a shared record, later households repeated the same survey questions and accepted weaker scopes. One installer quoted for a 7 kW pump without a room-by-room heat-loss calculation; another included a full radiator schedule but no servicing visit. Residents could see the price gap but not the scope gap.
Solution: a staged bulk buy with one scope
Six households formed a buying group and wrote a single specification: room-by-room heat-loss survey, MCS-certified installer, radiator schedule, 12-month servicing, and a shared scaffold plan. They invited seven installers to tender, shortlisted three, and chose one on price and survey quality. Coordinated delivery meant one scaffold lift for four homes and one commissioning visit per pair of properties.
- Step 1: Agree a common scope before requesting quotes.
- Step 2: Tender to a shortlist, not a single installer.
- Step 3: Publish anonymised results so late joiners can compare.
The group also set a rule that no household would sign until the survey showed radiator sizes and flow temperatures. That single rule removed two weak quotes from consideration and gave the chosen installer a clearer brief.
Result: lower costs and a repeatable model
The first phase covered 17 homes. Pre-grant installed cost fell from an average £11,400 to £8,950, and annual gas use dropped by 41% across the group. Two lessons survived the winter: fabric measures must come first, and the group needs a public ledger of quotes and outcomes. Bananzia now has a waiting list for phase two, but the model is not magic; it is coordinated procurement with better information.
For other streets, the transferable asset is not the installer name but the specification. A clear scope, a short tender list, and a shared record turn a private retrofit into a repeatable local project.