This completely introverted single-family residential building, designed by I/O Architects, is located on the last lot of a desirable neighborhood on the outskirts of Sofia. The complexity of the set program does not match the size of the property, which determines the tree-like structure of the house. Each of the three floors is different in size and concealment strategy. The most extensive first floor is underground, yet naturally lit and directly connected to the street and garden.

The heating, cooling, pool heating and DHW of the house are provided by geothermal systems designed by Re Energy Engineering Ltd, which provide an environmentally friendly and energy-efficient solution for both winter and summer seasons, covering all the needs of the investor and the house itself. They use the stable ground temperature to regulate the indoor climate, reducing the carbon footprint of the house. This not only contributes to environmental sustainability but also results in significant energy cost savings for the house owners.

The compressed and mostly open ground floor together with the small garden is hidden behind the hedge.

The privacy and sunlight of the large upper floor are meticulously controlled by big-scale sliding panels. Only the simple hovering pigmented zinc volume and the blind entrance are exposed to the street while the rest of the complex structure remains unrevealed. The spaces inside are integrated around the light of the central atrium and pierced by unexpected space connections. The reflective roof of the deep veranda brings back a garden view to the interior. The linear underground space of the swimming pool has visual and physical contact with the garden while the bright garage is connected to the rest of the house through an under-stair periscope space.

The house won first prize in the ARCHINOVA ARCHITECTURE AWARDS competition in 2020 in the category "Realisations / Single Family Residential".