At Lancaster Close in Bromley (BR2), Excel Construction was main contractor on a whole-house energy upgrade of a 223 m² detached home: external wall insulation with a silicone render finish, an air source heat pump, solar PV and a Baulogic KNX smart home system. The finished house has an EPC rating of B (89) and an A environmental impact rating, and produces about 0.3 tonnes of CO2 a year, against a UK average of 6 tonnes.
Project at a glance
- Location: Lancaster Close, Bromley BR2 (London Borough of Bromley)
- Property: detached house, 223 m²
- Scope: external wall insulation and render, air source heat pump with underfloor heating and radiators, solar PV, Baulogic KNX smart home
- Main contractor: Excel Construction, working with MCS certified, Gas Safe and NICEIC registered specialist contractors
- Result: EPC B (89), environmental impact rating A, 16 kWh/m² primary energy use a year
Video tour
Fabric first: external wall insulation
The upgrade started with the walls. The house was wrapped in a 90mm EPS insulated render system, bonded and mechanically fixed to the existing masonry, with a mesh-reinforced base coat and a 1.5mm silicone render finish. The system was specified by the manufacturer for this property and carries a 10-year system warranty.
Before any work started, a U-value calculation and a condensation risk analysis were carried out. The insulated walls achieve a calculated U-value of 0.30 W/m²K, the Building Regulations standard for upgraded walls, with no condensation risk at any layer of the wall build-up.
Air source heat pump and solar PV
With heat loss reduced, the house was fitted with an air source heat pump feeding underfloor heating and radiators, with time and temperature zone control. The heat pump was installed by an MCS certified contractor, and part of its cost was covered by a Boiler Upgrade Scheme grant approved by Ofgem.
Solar PV on the roof generates electricity during the day, cutting the running cost of the heat pump. The EPC rates the main heating and heating controls as very good, and records both the heat pump and the solar PV as low and zero carbon energy sources.
Baulogic KNX smart home
The whole house runs on a hardwired Baulogic smart home system built on the international KNX standard. A wall-mounted touch panel controls heating room by room, along with lighting, CCTV, intercom, sensors and energy monitoring. Because the system is wired rather than wireless, it keeps working without Wi-Fi, and the cabling was installed at first fix while the walls and ceilings were still open.
The results
- EPC rating B (89), 3 points short of an A, against an England and Wales average of D (60)
- Environmental impact rating A: about 0.3 tonnes of CO2 a year, against a 6 tonne average
- 16 kWh/m² primary energy use a year
- Walls, roof and floor all rated very good for insulation
- Estimated heating, hot water and lighting cost of about £1,522 a year for a 223 m² house
Source: official EPC on the GOV.UK register, assessed May 2026.
Frequently asked questions
Can a smart home system be added to an existing house?
Yes, but a wired KNX system like Baulogic is easiest to install while walls and ceilings are open. At Lancaster Close it went in as part of a wider refurbishment, so all the cabling was run at first fix with no chasing out later.
Does external wall insulation make a heat pump more efficient?
Yes. Insulating the walls first cuts heat loss, so the heat pump can be smaller and run at lower flow temperatures. At Lancaster Close the insulated walls reach a calculated U-value of 0.30 W/m²K, and the EPC rates the walls, roof and floor as very good.
What EPC rating can a refurbished house achieve?
This detached house reached an EPC rating of B (89), near the top of band B, with an A environmental impact rating. The average home in England and Wales scores 60 (D).
Do you cover Bromley, Shortlands and Petts Wood?
Yes. We work across Bromley, Shortlands, Beckenham, Petts Wood and Orpington, as well as the rest of South London and Surrey.
Planning a low-energy home in Bromley?
We combine the building work and the energy systems under one contractor: insulation, heat pumps, solar, battery storage and smart home control. See our renewables and smart homes services, or get in touch for a quote.