Case study
4-Bed Detached Home — Full Retrofit, Surrey
- Property
- Detached, 1970s
- Sector
- Homeowner
- Location
- Surrey
- Services
- Air source heat pump · Solar PV (6kW) · Battery storage · Loft insulation · Cavity wall insulation
The challenge
High bills, uneven temperatures, and an ageing heating system that struggled in winter peaks. The homeowners wanted a single coordinated plan rather than piecemeal upgrades — they'd seen a neighbour end up with a heat pump that didn't work well because the insulation wasn't sorted first.
Our approach
We completed a full whole-house assessment aligned to PAS 2035. Cavity wall and loft insulation were sequenced first to reduce heat loss, then a correctly sized air source heat pump was specified. Solar PV with battery storage was added to optimise self-consumption during daytime hours.
The results
EPC improved from E (44) to B (89). Annual energy cost reduced by £1,240. The installation was completed in three days of on-site work, spread across two weeks to fit the family's schedule. All documentation lodged with TrustMark within 48 hours of completion.
Annual saving
£1,240
EPC improvement
E → B
CO₂ reduction
4.2t / yr
“We budgeted for disruption and got almost none. Three days of actual work, spread across two weeks to fit our schedule. The house is warmer than it's ever been and the energy bills for the first winter were genuinely shocking — in a good way.”