Co-operative retrofit of a Manchester Victorian terrace
A whole-house deep retrofit of a solid-wall Victorian terrace in Manchester, delivered through Carbon Co-op and published as a worked example.
Source
Summarised from Carbon Co-op, a Tier 2 source on Your Home Climate. We did not run this project; the figures below are reported by them. Click through to verify any of them at the original publication.
https://carbon.coop/portfolio/case-studies/The problem, before any work started
An 1890s end-of-terrace in a Manchester conservation area: solid brick walls, a suspended timber ground floor, original sash windows, and a heating bill that rose with every cold snap. The owners wanted a low-carbon, comfortable home without leaving the street they had chosen for the street itself.
What actually happened
- 01A Carbon Co-op Retrofit Coordinator scoped a PAS 2035-compliant package for the whole house.
- 02Internal wall insulation was used on party walls; external wall insulation was added at the rear where the streetscape allowed it.
- 03The suspended ground floor was insulated; secondary glazing was added to retain the original sash boxes.
- 04A small MVHR was installed and an air-source heat pump was sized for the reduced heat loss, running at a 45 °C flow temperature.
- 05Works were sequenced over twelve months around the family, not delivered in one disruptive hit.
What changed for the home
- The house moved from gas at high flow temperatures to an 8 kW air-source heat pump at 45 °C.
- Secondary glazing preserved both the streetscape and the acoustic improvement the family actually wanted.
- Whole-house heat loss fell far enough for the heat pump to be sized modestly rather than oversized for the original fabric.
What the source reports
- Standard followedPAS 2035reported
- Heating system after retrofit8 kW air-source heat pump at 45 °C flowreported
Measured means monitored data from the site. Reported is the publisher's stated figure. Modelled is a target or design figure rather than an outcome.
What this case can, and can't, tell you
What it tells us
- A coordinated PAS 2035 approach lets a solid-wall Victorian terrace run on a modest, low-flow-temperature heat pump.
- Secondary glazing is a serious option in conservation areas, not a compromise.
- Sequencing work around an occupied family is possible when there is a coordinator holding the plan.
What it doesn't
- Whether the cost-benefit balance holds for owners who would not otherwise refit kitchens or bathrooms; internal wall insulation pays back its disruption only when integrated with other works.
- How the same package would perform in a different climate region or on a mid-terrace with less rear access.
- Long-term running-cost outcomes; published monitoring is short-run and the tariff landscape keeps shifting.
Our take
This is the case we point at when a homeowner says 'we have an old terrace, surely a heat pump is out of reach'. The honest answer is: not out of reach, but conditional on doing the fabric work first and on having one person responsible for the plan. The cost of skipping either is paid every winter for the rest of the building's life.