Graha Wonokoyo
An office building using a colonial architectural approach because of its conservational site locaton. It is designed to rise upward gradually with two of the front floors allocated as the reception building following the typical colonial architecture widely found in this area. The 3 stories high middle part serves as a transitional structure from colonial to modern style, is also used for a hall with a gallery and collective meeting room. Lying lengthwise from north to south is a 11 stories tower, which is located at the back of the compound. The tower is considered as the climax of this complex.
The rich colonial style can be found on its composition, wall, and glass proportion, as well as an energy cutback concept, known as OTTV (Overall Thermal Transfer Value). This value is employed throughout the building for the design of the conditioned wall and glass in the exterior like AC system. According to the Energy Efficiency Index (EEI) by the Energy Development Division of the Ministry of Mining and Energy, the energy consumption standard for a hi rise office building should not exceed 200 kwh/m2/year.
To reduce the sun radiation effect from east to south, the window details on those sides of the facade are fashioned using neo-classical element, which also help trim down the size of the glass. Considering the high level of radiation from north and west compared to other directions (North: 40-100 kwh/m2, West: 80-120 kwh/m2 and South: 30-40 kwh/m2, East: 40-50 kwh/m2), high performance glass with a low shading coeffiecient is chosen to lessen the cooloing load of the AC system. Complementing this is the natural lightning from open space illumination, at an average 10,000 lux for Indonesian area. The AC system uses the Variable Refrigerant Volume (VRV) schematic, that enables independent adjustment on each floor, which results in a reduction of building operational costs.
Materials for the facade are chsen meticulously to reduce the heat inside the room. These include a combination of metal cladding and V-cool coated high performance glass in the west side, as well as granite and aluminium panels in the reception building. The layout of Graha Wonokoyo closely follows the concepts elaborated above and is divided into 3 zones. The west side acts as a thermal barrier, therefore, used as a reception area, a meeting room and public service. The north one is used as outdoor room for AC units, pantry and filling room. The main zone lies in the south and east side.