The buildings interact with their surroundings by means of the lower two levels housing shops, restaurants and offices, the entrances to the towers and the parking facilities. The Towers also relate very successfully to the larger scale of the city. Their location just outside the city centre was chosen in order to avoid increasing traffic in urban zones which are already problematic. At the same time the Towers are within walking distance of Sofia’s metro, due to the investor’s ambition to establish Sopharma Litex Towers in Sofia’s urban life in the most sustainable way possible. In this way the Towers are a well-measured urban gesture, which rather adds urban life to the city fabric, than pulls it away from it.

Not only are the Sopharma Litex Towers cleverly integrated into Sofia’s urban fabric, they also utilise building technology which would be innovative anywhere in the world. The project was an experimental collaboration between the investors (Sopharma and Litex), the architect (Architectonika), the façade consultant (Dr. Helmut Koester and physicist eng. Kiril Velkovsky), fabricator (Kristian Neiko 90) and the façade system developer (Reynaers).

According to Kiril Velkovsky, the Towers proved to be a very good symbiosis between the architect’s ambition for a high-performance, energy-efficient building and the technology provided by Reynaers, which backed up and strengthened the original design idea. For this project, comprising 20,000 m² of façades, a new façade system was developed, based on the CW 86-EF element façade with CS 86-HI windows, which could satisfy the requirements of the investors for a low-energy footprint and still result in an extremely flexible and comfortable building. This element façade – measuring 14,000 m² in total – is made with elements that were preassembled and glazed in the workshop.

The efficiency of the building’s climate control is also reinforced by the use of a Building Management System (BMS), a network of computers, which monitor and control all heat, light, energy and waste processes. The concept, called ‘adaptive façade’, comprises five working regimes. Because the buildings have their own meteorological station that reports the changing climate conditions, the system can decide which of the possible scenarios will be most effective. The façade solution was extensively tested in the Reynaers Institute and in CSTB in France.

This system makes it possible to adjust the building’s behaviour individually in different parts of the building, in relation to the outside climate conditions and the use of the interior. At the same time users have direct control over the environment of their office in terms of light, ventilation and heat. In the words of the architect Paskalev this is one of the factors, which have led to tenants’ and users’ great satisfaction with the building.