award 2017
Building of
the year 2017
Nomination in
Residential buildings

Advanced Architecture Apartments. A Building that Inspires

A3. A Building that inspires

Conceptual design

A3 – Advanced Architecture Apartments is an exhilarating residential building, which blends in harmoniously in the environment in which it is situated. The architectural concept is shaped by two points of reference – the mountain and the city. The designated А3 site is situated along the borderline where the city and the mountain merge into one. The lines and sharp boundaries are mellowed down in undulating, smooth forms that enabling onlookers to perceive the exact location and shapes and space in a highly individualized manner. Situated in one of Sofia’s most prominently contemporary areas – the Bulgaria Boulevard – the underlying concept of А3 is of an avant-garde, highly contextual and modern edifice. Some of Sofia’s most architecturally advanced buildings are situated along the stretch of the thoroughfare, including two of Sofbuild’s landmark creations. On the other hand, the dominant feature of the landscape is the mountain shyly overlooking the future building. By combining these robust elements, we have designed a building with a thrilling, dynamic and contemporary shape of unsurpassed functionality. 

The building has been split into five well-defined volumes linked into an ensemble that outlines the overall silhouette. Each of the five constituent parts has stylish, rounded forms leaving the imagination room for free association and interpretation. Although the five elements lend themselves to an easy association with five mountain tops or the silhouette of a family with three children, at a deeper conceptual level out idea was to leave sufficient room for free associations, allowing each individual to forge an intimate connection with the building, give each shape a unique meaning and transform it into a source of inspiration. 


The А3 was designed from the outside in, i.e. it follows the prime imperative of function—an approach that we firmly believe to be the best to follow in residential building design. We have designed an uncompromisingly sound functional scheme that is fully in line with the investor programme. The blueprints reveal regular, orthogonal shapes that provide abundant living comfort and flexibility in terms of interior design solutions. 

We have split the building’s plan of more than 100 metres into five units (entrances), each complete with its own vertical communication solution. Units A and B each comprise two apartments on each floor, and Units C, D and E – three. The small number of apartments heightens the sense of exclusivity and provides more personal space. We have achieved the desired technical and economic indicators of 11 % common areas. Each apartment has excellent functionality and a favourable geographic situation. All daily living spaces face East-Southeast and are adorned with richly decorative glassware, overlooking Mount Vitosha and the city outline. The ground floor is intended for retail stores with a floor area from 50 up to 100 sq. m. Parking is ensured at two ground levels and the surrounding area will be fully landscaped with ample recreation opportunities. 


The А3 combines sharp stylishness and soft organic forms. The building is smooth and easy on the eye as a single silhouette and from different perspectives alike. The perception of style and sophistication is further enhanced by the façade materials to be used – glass and glass fibre concrete. The glass comes in two shades – transparent and graphite Lacobel. 

In addition to its highly pleasing aesthetic properties and functionality, the materials ensure durability and easy maintenance over time. 

STARH EOOD, Architect Svetoslav Stanislavov


A3’s design is based on monolithic ferro-concrete structure complying with the latest European unified construction standards EUROCODE. To ensure best construction quality parameters – great strength and low deformability, high-strength concrete of class C30/37 and reinforcement steel of class B500 are used. The foundation of the building represents a foundation slab, 1.40 m thick, which is a guarantee that no defects will appear on walls, floors or ceilings resulting from irregular subsiding of the earthen basis. The floor slabs are 25 cm thick which improves greatly the noise-isolation between the separate floors, and the columns are distributed in such a way as to be usually accommodated within the walls separating the apartments, thus eliminating any restrictions as to the free architectural planning of the interior.

In the seismic aspect, the structure of А3 is unique since there are no deformation joints between the individual sections, which provides for the latters’ joint resistance to seismic impacts. Even in case of the strongest possible earthquake, А3’s stability would not allow for any cracks to appear on walls, floors or ceilings. Actually, this is the latest tendency in the seismic design of great buildings and А3 is the first residential building and the third of all buildings in Sofia belonging to this “family”, next to PARADISE CENTRE and MEGA MALL.

AEC EOOD, Dipl. Eng. Iliya Alashki

Water-supply & Sewerage Installation

1. Water-supply installation:

1.1. For domestic needs. 

The pipes of the water-supply installation are made of polypropylene. This type of pipes are not prone to furring and corrosion. The neat area does not change throughout the operation period, and therefore, no pressure variations are expected.

The consumed water is measured by remote sensing water meters and therefore, no collector home visits are required.

Hot water is produced by individual gas-fired boilers located on the estate.

1.2. For fire safety needs. 

The fire safety installation consists of fire safety cassettes located on each floor, which are furnished with a sprinkler and a hose, 20 m long. They are assembled discretely within the building’s structural components.

2. Sewerage installation:

2.1. For domestic needs. 

The envisaged pipes of the sewerage installation are of the „noiseless“ type. The material and structure of the pipes, as well as the measures taken during their assembly and stabilization, provide to reduce to minimum the noise produced by outflowing water. 

2.2. Drainage installation.

A system of chutes, grids and pipes is envisaged to collect and evacuate all rain water. The chutes which are assembled „invisibly“ under the floorings of the terraces will function without disturbing the aesthetical outlook and design of this part of the building.

2.3. Drainage of air conditioners and gas-fired boilers.

The drainage installation of the air conditioners and the gas-fired boilers is entirely invisible and extremely reliable. It will be included in the building’s sewerage system through siphons. This will prevent penetration of sewerage gases into the air conditioning bodies and from there – into the residential premises.

Building International OOD, Dipl. Eng. Evtim Dimitrov


Lighting and power installations

The electric energy consumed in the building will be measured by main electrometer switchboards (MESB) assembled on the front of the building’s entrances in self-contained premises intended only for electrometer boards, using mono-phase and three-phase double-tariff electrometers.
The shops will be provided with three-phase power-supply from the MESB of the respective entrance through cables laid inside PVC pipes hidden behind plasterboard walls or assembled on metal racks inside the suspended ceiling of floor 1. 

The apartments will be provided with mono-phase / three-phase power-supply from the MESB of the respective entrance through cables laid inside PVC pipes, positioned vertically within a special groove cut into the structure.

The lighting of the staircase cells will be switched-on by light-buttons mounted at the staircase landings.

The lighting of the corridors in front of the apartments will be switched-on by light-buttons mounted in the corridors or inside the apartments.

In the shops – All consumers will be power-supplied from the respective electrometer boards. The electrometer boards will be provided with input automatic switch and output automatic fuses. Additional current failure protection units (CFPUs) are provided for the current contours of the general-purpose contacts, the technological equipment contacts and the workplace contacts.

The lighting of all premises will correspond to their function.

Above the suspended ceiling, vertically, behind plasterboard walls, the following installation will be laid: 

  • for the lighting – by a cable laid within corrugated pipes behind plasterboard walls and fixed by brackets above the suspended ceiling, which will be operated by on-site switches;
  • for the technological equipment contacts – by a cable laid within corrugated pipes behind plasterboard walls;

In the apartments – All consumers will be power-supplied by an apartment electrometer board. It will be assembled at an appropriate place in the entrance hall. The apartment electrometer boards are provided with input automatic switch and output automatic fuses. Additional current failure protection units (CFPUs) are provided for the current contours of refrigerators, heating plates, ovens, dishwashers, washing machines and general-purpose contacts.

The installation will be implemented as follows:

  • for the lighting – by a cable laid within corrugated pipes behind plasterboard walls and fixed by brackets above the suspended ceiling, which will be operated by on-site switches;
  • for the contacts of the individual consumers – by cables laid within corrugated pipes behind plasterboard walls;

The lighting of all premises will correspond to their function.

Telephone installation, Antenna installation, Internet

At certain places on the building’s ground floor, weak-current cabinets for the individual entrances will be mounted, from which a cable will be drawn accordingly for each of the following: telephone installation, cable TV antenna installation, and structural cabling – Internet to shops and apartments. 

Accordingly, in each apartment and shop, a PVC box for the weak-current installations will be mounted. The electric contacts (ECs) will be connected to the PVC box through a corrugated pipe. Out of the assembled weak-current cabinet, the individual output cables will be drawn which will be laid behind plasterboard walls. The outputs of the respective installations will end at Internet sockets RJ 45, flush-mounted 0.35 m off the finished floor.

Doorbell and Intercom installation

Within the main electric board of each building entrance, power-supply blocks for the intercom installation and the electric lock will be mounted. 

The intercom installation will include an intercom receiver in each apartment connected to the ground floor board with intercom speaker and doorbell buttons mounted at the entrance of each block of flats.

All receivers will be provided with built-in zoomer, which will ring in a different way depending on where the call comes from – the entrance door of the block of flats or the entrance door of the apartment.

Lightning protection installation

The object features lightning protection of the III category. To protect the building from direct and indirect lightning hits, a lightning protection installation has been designed.

Earthing installation

The earthing installation is a major component of each electric installation. It is installed to restrict high voltage and lead into the earth the great electrical charge which may be generated when a lightning hits or when commutation processes in the power-supply system occur. The earthing installation removes or restricts the risk of electrical installation failures, thus protecting people and equipment from dangerous voltages.

Dipl. Eng. Vasko Milenkov


Heating and air conditioning

The air conditioning systems all over the building are high-tech, effective, power-saving and featuring low carbon dioxide emissions. 
Each owner will feel comfortably during the transitional periods and the winter season thanks to the individual heating installations with gas-fired condensing boilers of the latest generation, featuring modern technology and exclusively great efficiency. The equipment is of compact make-up, all its working and protective fixtures are contained within, it complies with the heating requirements, and it provides for quick heating of water for domestic needs. The customer may easily optimize operational costs, using the expanded user interface, and setup different regimes, varying the boiler’s output between 15% and 100%. The equipment does not burn the oxygen contained in the premises, but receives oxygen from the air outside through an integrated chimney system through which the exhausted gases are also released. If some of the burning parameters be disturbed, the equipment’s emergency functions are activated. 

Each apartment located close to the boiler is furnished with gas analyzer, which registers and controls centrally the safety and stopping fixture along the gas line in case of gas leakage.

The internal heating bodies intended for the apartments are aluminum radiators and aluminum heating tubes for the baths.

The internal heating bodies intended for the commercial halls in the shops are of the cassette type, supplied with ventilating convectors and fittings for ceiling assembly. 

With a view to the summer period, the apartment sitting-rooms are supplied with pipings for potential assembly of split air conditioners with direct evaporation of the invertor type. The external aggregates will be installed on the office terraces at the respective inter-floor level. 


The air exchange in the building is organized in such a way as to ensure the sanitary and hygienic microclimate norms and air cleanliness. No mechanical ventilation has been provided for the premises that can be ventilated directly.

All WC, bath and warehouse premises in the apartments and shops are provided with domestic sucking valve ventilators, which are operated by the lighting key.

In case of heavy smoke or heat emission (fire), all staircase cells and lift shafts are furnished with ventilation system to provide for safe evacuation.

Sucking installations for the two garage levels are constructed, which emit polluted air into the green space outside. The compensating fresh air penetrates freely through the two garage doors.

In case of emergency and a signal produced either by the fire-alarm installation or manually, the emergency sucking and injection ventilators for each self-contained fire area are activated. 

On the explicit mission of the Investor, no cars with gas (methane)-fired installation will be let into the underground garage.

ATARO CLIMA EOOD, Dipl. Eng. Kalina Petrova