An extension and a deep retrofit of a detached Edwardian house in Newnham, Cambridge. (Shortlisted to the Greater Cambridge Design and Construction Awards 2024 under the Best Conservation, Alteration, or Extension of an Existing Building (under £2m construction costs) The family home was extensively extended towards the rear over three storeys, and the front bay window was added to the first floor. New kitchen, library, WC and a generous living room were added on the ground floor. The first floor master bedroom was enlarged and additional built in storage units were tailored to all bedrooms. A second floor study was added to the rear. The original buiding and structure were retained and internally insulate, and new triple glazed windows were introduced to improve the external envelope air tightness and thermal performance. The house services were decarbonised by removing gas completely, with heating supplied by an air source heat pump and power from photovoltaic panels.