Feilden+Mawson have successfully completed the refurbishment of this Grade II listed Mews house to the Passivhaus EnePHit standard, which had been identified as a robust upgrade to achieve low energy and low carbon targets using high levels of thermal insulation, low air permeability and no cold bridging between components. The project included the introduction of a new airtight layer within the build-up of the building envelope, the installation of high performing but breathable insulation, the introduction of a new mechanical ventilation system with heat recovery, as well as the installation of new high-performance secondary windows, doors and rooflight. All mechanical and electrical services have been replaced and upgraded throughout. Following the successful accreditation of this Passivhaus refurbishment, the energy performance of the building is being monitored and subject to an ongoing review involving all parties. Both client and design team have expressed how this project has met all expectations in both performance as well as aesthetics, without one unduly compromising the other.