This low-energy refurbishment of this Cambridge house was designed in 2022 to achieve very low-carbon targets. We took a typical solid-walled 1950s housing stock, and transformed it into a highly energy efficient home with considered spaces and bespoke joinery tailored to the client’s needs. Low-energy services include an air-source heat pump with underfloor heating and a mechanical ventilation with heat recovery system, ensuring a continuous supply of fresh, filtered air. The home was extended to front and rear and wrapped in breathable external insulation, clad with a combination of natural sycamore and crisp white render, with a natural sedum roof. Despite the increased floor area, the new low-energy design reduced overall heating demand by 75%, meaning a like-for-like saving of almost 90% on previous heating bills.