This project showcases a ground floor rear extension to a semi-detached 1930's house in Hampton Hill, a suburb of London. The kitchen and dining room are connected laterally to a new lounge area which creates an open plan space overlooking the garden. The lounge extension is limited in width to retain a small west facing patio to optimise its sunny disposition in the afternoon. An environmentally conscious triple glazed window wraps the corner to open the view towards both the rear garden and the side patio. The panoramic window and a large minimalist detailed skylight offer daylight throughout the space. The amount of optimal daylight received in the extension was simulated with various computer programs and using different daylight metrics. The new modern lounge extension is designed to subtly mark the difference in architectural languages with the existing house.