At the beginning of 2008, the company „Tangra” won a tender to execute the ventilation, heating, and air-conditioning installations for the East Tower office building, with BGI Project acting as the project consultant.
The building is situated on a plot of 1,520 m² with the main entrance from G.M. Dimitrov Boulevard. The structure has 10 floors and two basements, with a total built-up area of 10,720 m². The basements house underground parking and technical rooms. The ground floor includes a lobby, a bank office, and a restaurant. All other floors consist of office spaces.
A central air-conditioning system provides heating and cooling for the rooms. For this purpose, five TONON Forty water-cooled units with air-cooled condensers are installed in the building’s attic space. Four of the units supply the rooms located along the northeast and southwest facades of the building, with the option to regulate the operation of the chillers by facade. This allows one facade to be heated while the other is cooled, depending on external conditions. The fifth unit supplies the installations on the ground floor.
Wall-mounted fan coil units, operating for both heating and cooling via a four-pipe system, are installed in the rooms. Additionally, ducted fan coil units are installed to supply fresh air to the office areas. Their function is to provide additional heating or cooling of the incoming fresh air so that it enters the workspaces at an appropriate temperature.
Separate ventilation systems have been designed for the lobby and the restaurant, calculated based on the minimum amount of fresh air per person. Additional fan coil units are also provided for these spaces, operating without fresh air supply, with the goal of achieving energy savings when there are fewer people in the rooms.
For supplying fresh air to the office floors, we installed two central air-handling units from TANGRA with energy recovery efficiency of Emax = 60%. The units are installed in the attic spaces, with their operation again distributed by facades.
For the restaurant kitchen, a supply ventilation system has been designed with a compact air-handling unit installed in the suspended ceiling. The extraction of air from the kitchen hoods, located above the work areas for preparing hot food, is carried out through a separate system that vents odors and fumes directly above the ridge of the building. The fans are specially designed for handling greasy fumes – with backward-curved blades and an external motor, model TA.
Since the building is classified as high-rise, to comply with all safety requirements, a ventilation system creating overpressure has been installed in the stairwells, corridors, elevator shafts, and lobbies leading to the underground garages. The system is designed in accordance with the Fire Safety Construction and Technical Standards of the Republic of Bulgaria. The fans are installed in the attic space. In case of a fire, emergency fans are also installed to expel hot air, featuring backward-curved blades and an external motor, certified to operate for up to 2 hours at an air temperature of 400°C, from the CRMT series by Soler & Palau.
A triple air exchange is provided in the underground garages, as required by the Fire Safety Construction and Technical Standards. A separate supply system has been installed to deliver fresh air. The exhaust air is discharged above the building’s roof through suction fans supplied by the Spanish manufacturer Soler & Palau – model CMT. Ducts and grilles for both top and bottom intake are provided to ensure the removal of both light and heavy gases. The system is equipped with fire dampers.
Thanks to its good location and the high-quality execution of all construction and installation works, today the building is an attractive place for major companies such as UBB, VMware, and Renault-Nissan.
