Thank you for allowing some more time to develop the scheme.
Conceptually I expressed the existing structure as a plinth or 'socle' which supports new accommodation in a lightweight steel frame with standing seam and flat sheet rheinzink cladding. Artificial lawn and landscaping planters are added to the roof to integrate the existing structure with the lush natural surroundings.
At first I tried to integrate the new build with the existing structure, but with little success. The final scheme expresses the new portions as a separate entity 'clipped; onto the 'socle'. However, Architecturally, the new portion utilises strong angular Platonic geometries, which complement and enhance the existing dwelling.
Spatially, a lush Atrium with a live tree and planted green wall forms the heart of the house, together with a lightweight stairwell - enhancing a sense of flowing space. The atrium is side lit to prevent unnecessary waterproofing and insulation challenges at roof level.
The main bedroom suite is a large loft-like space with natural light spilling through dormer windows and down the Atrium. Large sliding foldaway doors open the bedroom and bathroom to a South terrace.
I tried to use the basement level windows as is and made minor modifications on ground floor level in order to keep costs down. Money is spent on the atrium and new portions of the house.
Also note that whilst compiling the presentation I decided to explore an option where one dormer window is omitted over the bathroom.
Finally, I have not designed the home entertainment system, under floor heating, etc., rather focusing on the spatial and aesthetic elements of the house.