The Michaelis House, at 95a Oxford Gardens W10, makes cunning use of London's strict planning laws by expanding the urban site in the only possible way - downwards.
In the process, the architects managed to extract maximum environmental efficiency out of a generously sized home, even when it has five bedrooms and a swimming pool.
Alex Michaelis bought the plot, complete with planning permission for an underground property, for his own use, and set about transforming the existing plans into a discretely luxurious but very low energy space.

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See more images of Alex Michaelis' underground masterpiece
From the street, the Michaelis House gives little away. An existing high wall concealed the plot, and behind this the diggers set to work, excavating down one and a half storeys so that the main body of the house barely rises above the bricks.
The project required careful consultation, with owners of neighbouring properties mollified by the expanse of green sedum roof they can now see from their windows. From the front gate, a winding ramp leads down to the entrance level, set a half storey below ground level. This floor houses the living rooms, with a kitchen, dining space and seating area soaking up a surprising amount of daylight from the generous rooflights and windows that look out on the narrow courtyard garden.
Bedrooms are located downstairs in the sub-basement, as is the pool, while the main staircase is enhanced by the addition of a slide for smaller members of the family. Daylight is brought into the deep space by a combination of sunken courtyards and rooflights.

Digging down also resulted in lots of natural insulation, enhanced by thick walls and the sedum roof. In addition, Michaelis created a 300ft deep borehole to give the house a private water supply for heating and even drinking (after filtering). Thermal and photovoltaic solar panels provide heating and electricity, some of which is siphoned off to an electric car. The house was completed in 2004; in the ensuing five years, the technology on display has moved a lot closer to the mainstream.

Alex Michaelis and Tim Boyd run an established residential and commercial practice in West London, shaping the interior of everything from Babington House, the refurbished Electric Cinema and the Fresh and Wild chain of organic supermarkets. The studio was established in 1995, after the partners had spent time working for the Richard Rogers Partnership and Wickham Associates now called Wickham van Eyck Architects.