A 1930s semi-detached house in Muswell Hill given a comprehensive eco-retrofit — targeting EPC A rating through external wall insulation, solar PV, air source heat pump, triple glazing, and sustainable material choices throughout the full internal renovation.
Our clients — a family of four with strong environmental values — had purchased this 1930s semi in Muswell Hill as their long-term family home. The house was a G-rated energy sponge: solid walls with no insulation, single-glazed metal windows, an ageing gas boiler, and no renewable energy generation. The brief was ambitious: transform the house into a near-zero-carbon home without sacrificing the comfort and beauty of the interior renovation they were planning anyway.
We developed an integrated eco-retrofit and renovation strategy that tackled the fabric first, then the systems, then the interior — a logical sequence that avoided costly reworking later.
150 mm phenolic EWI system to all elevations, reducing U-values to 0.15 W/m²K. Finished with silicone render and new window surrounds.
6.5 kWp system (16 panels) to south-facing rear roof. Paired with a 10 kWh battery storage system for overnight use and EV charging.
12 kW Mitsubishi Ecodan ASHP replacing the gas boiler. Coefficient of Performance (COP) of 3.8 — delivering £3.80 of heat per £1 of electricity.
Aluminium-framed triple-glazed windows throughout, replacing all original frames. U-value 0.7 W/m²K. Significantly improved acoustic performance as a bonus.
Whole-house mechanical ventilation with heat recovery — recovering 85% of heat from extracted air, maintaining air quality without heat loss.
Low-temperature underfloor heating throughout ground floor, optimised for heat pump operation. Significantly more efficient than radiators at heat pump flow temperatures.
The house achieved an EPC rating of A (92) post-completion — a dramatic improvement from G (14) at purchase. The family's energy bills are projected to fall by approximately 76% compared to the pre-renovation baseline, with the solar array and battery further reducing grid imports. The air quality and thermal comfort of the house have improved dramatically — warm in winter without the cold spots and draughts the family had previously experienced, and cool in summer thanks to the insulation's thermal mass effect.
The project qualified for several government incentives including the Boiler Upgrade Scheme (£7,500 towards the ASHP) and local authority insulation grants, reducing the net cost to the client.
We design and deliver whole-house eco-retrofits across North London. From EWI to heat pumps and solar — we manage the full package. Contact us for a free assessment.
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