THE DRIVE | We are working on a retrofit to an existing semi-detached home in Brent, London. This bespoke rear extension and full whole house retrofit has been designed to Passivhaus (Enerphit) standards and will include adopting a fabric-first approach as all walls, roofs, and floors will be newly insulated; incorporate an mechanical ventilation with heat recovery (MVHR) for superior internal comfort, and will be fossil-fuel free (installing an air source heat pump (ASHP)). The refurbished homes is due for completion by the end of 2023.