C16th Grade II listed Mill House in Gloucestershire was purchased by the client with the ambitious goal of combining a sympathetic restoration with advanced eco-refurbishment, following destructive modernisations by the previous owner. Positive collaboration between Hetreed Ross Architects and the listed building officer resulted in the conservation of the house while achieving lower energy consumption than homes of more recent construction. Sustainable measures included PVs, super-insulated heated floors, high performance timber windows, full external wall insulation using ‘breathable’ cork slabs and lime render, ASHP backed up by wood stoves and individual heat reclaim extract ventilation. The replacement of modern lean-tos with a cedar-framed double glazed conservatory proved uncontroversial.