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Architects: Kliment Ivanov Architects
- Area: 2704 m²
- Year: 2019
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Photographs:Nikolay Stefanov
Text description provided by the architects. Kalistratov Group is a renowned family-run construction company in Bulgaria. The family aspect is paramount as the company considers its employees as an extended family. The new headquarters accommodate the current staff and foresee future expansion. Two key requirements were posed by the clients – an impressive but restrained building, demonstrating the company’s capabilities, and a working environment in contact with nature.
The glass-box building and the open-plan office layout were discarded from the very beginning. Instead, a more enclosed scheme was preferred, providing a state-of-the-art working space. Amenities include an individual office and a parking-place for each employee, a meeting room, a projects archive, a print room, and a kitchen on every storey, along with a roof terrace, a glazed “sun room”, a yoga gym, and a restaurant for all the staff.
The plot is located next to a park with a historic spa complex. Three problems occurred – an existing unfinished building in it, an authorities’ resolution to keep the existing structure and foundations, and a restriction of the building’s height and foundations’ depth due to underground mineral water. The existing structure was stripped entirely and preserved with minor interventions only. The new car-park has a separate structure.
The movable sunscreens are the main feature of the design. Their changing position reflects the sun’s movement and the inhabitants’ moods. Made from perforated aluminium sheets, they are specially designed to prevent overheating, reduce glare, and provide privacy. Extensive testing with 3D models and real samples determined the most efficient form, size, and pattern of the holes. They consider the facade’s orientation – twice larger to the north, serving for privacy only.
Energy efficiency by natural means is the key priority. It comprises orientation, sun-shading, and natural ventilation. Floor-to-ceiling windows in every room frame views to the outside and can be opened to let fresh air in. The long south facade generates heat gains in winter, but the sunscreens protect it from overheating in summer. A Bulgarian traditional architecture principle is used for the ground storey – the deep cantilever above stops the high summer sun, but lets the low winter sun pass under it. Separate temperature control in each room allows the air-conditioning to be switched off when unused. The strong visual identity of the building engages and enriches the surrounding area, setting a benchmark for future development in terms of design and sustainability.
