Skyscrapers Architecture Analysis
- 2. Chennai city south - Skyline Completed in 2009, the Burj Khalifa, in Dubai is currently the tallest skyscraper in the world, with a height of 829.8 m.
- 3. THE ABSENCE OF ADEQUATE DESIGN CRITERIA • Although the principles of designing with climate are , relatively advanced for low-rise and medium-rise buildings, attention and research have yet to be directed to the tall building type or 'skyscraper'. The need for greater attention to this field is evident • Historically, tall buildings were structures that symbolized religious expressions or imperial monumentality. • We might compare the high-rise building with the 747 aircraft. Like the airplane, it has become an international piece of technology which every national economy owns.
- 4. What is the tall building? It can be regarded primarily as an intensification of built space over a small site area (or over a small built footprint). We might better define the skyscraper as a multi-storey building generally constructed using a structural frame, provided with high speed elevators and combining extraordinary height with ordinary room-spaces that would be found in low buildings. The CTBUH (Council of Tall Buildings and Urban Habitat) defines tall buildings as of ten-storeys or more because that is the cut-off height for fire-fighting from ladders in New York City.
- 5. In seeking to optimize the land-area, the tall building's economics seek to have the maximum internal area on each floor (net areas), and the maximum gross building area for its site (i.e. maximum plot-ratios and minimum 'net-to-gross' ratios). In order to achieve these economic objectives, the following criteria are critical: • Minimum external wall thickness • Minimum vertical support size • Minimum horizontal support thickness • Minimum vertical circulation/service core area • Minimum floor-to-floor height
- 6. PROBLEMS OF BUILDING IN THE HOT-HUMID CLIMATE The hot-humid climatic zone is characterized by • high ambient temperatures (21-32°C), • high humidity, • high and fairly evenly distributed rainfall, • small daytime and annual variations of temperature, • little seasonal variation, light winds, and long periods of still air Discomfort -feeling of skin wetness. Continuous ventilation is required. Radiation solar heat gain should be prevented. The hot-humid zones present two problems to constructors: • Avoidance of excessive solar radiation, and • Provision for moisture evaporation by breezes.
- 7. 1.Traditional houses in this climatic zone have floors which are raised to keep them dry and to allow for air to circulate beneath. In urban planning, the preference is for 'CHEQUER- BOARD' spacing of buildings to enhance air-circulation. Under hot conditions, the thermal controls in the building should: • prevent heat gain and maximize heat loss (can be achieved by means of 'microclimatic control') • remove any excess heat by mechanical cooling. (can be achieved only by means of an active energy input or by mechanical means of control.)
- 8. 2.SERVICES CORE POSITION The position of the services core is a key consideration in the planning of the high-rise building's floor-plate and in determining its configuration. Essentially there are three possible types of core positions: 1.'central- core', 2.'double-core' 3.'single-sided core
- 9. These zones should have natural ventilation, sunlight and a good view to the outside wherever possible. This principle dictates a peripheral rather than a central-core position. By providing a pleasant view from these areas, the users of the building can see out and experience the natural environment as soon as they exit from the lift-car and can have the opportunity to experience natural sunlight and ventilation. NATURAL VENTILATION AND SUNLIGHT TO SERVICES-CORES The services-core are parts of the tall building which contain the lift shafts, lift lobbies, main and escape stairways, riser- ducts, toilets and other service rooms.
- 10. CENTRAL CORE ADVANTAGE: i.it allows all window space to be utilized as rental office space. ii.Permits offices to varying depth to receive natural light. iii.It is suitable in terms of access and in some cases may be equidistant from all sides. iv.Simplifies area division. DISADVANTAGE: I. The central interior location limits the depth of the offices. ii. It requires an access corridor around its perimeter. Some examples of the central core: Equitable Building Place Victoria office Tower Alcoa Building etc All the above building cores are shown later. central core
- 11. EXTERIOR CORE Advantages: It leaves the entire floor area of the building available for tenant use. The core does not complicate the floor plan either functionally of structurally. Maximum flexibility is achieved with respect to tenant distribution of office depth and plan layout. Disadvantages: The core occupied desirable window spaces, so that, the offices immediately adjacent to the core may not receive any natural light.
- 12. DOUBLE CORE Advantage: The double cores are placed on the hot sides (east, west) thus, provide buffer zones, and minimum air-conditioning is required. The window openings run through north and south. Lift lobbies, stairways and toilets are naturally ventilated and a view out is possible. The double core has more flexibility in floor area division. Disadvantages: If the building is not that big, then it becomes costly. Some examples of the central core: One first national plaza Overseas Chinese Bank etc.
- 13. 3.BUILDING ORIENTATION •Tall buildings are exposed more directly than others to the full impacts of external temperatures and direct sunlight. So their overall orientation has an important bearing on energy conservation. •The greatest source of heat gain in the hot-humid climate can be the solar radiation entering through the window. •Windows should face the direction of the least direct solar insulation i.e. on the north and south sides, in conjunction with curtain walling if this is deemed aesthetically desirable If the site does not align with the sun's geometry on it's east-west path, other built-elements such as the services- cores can follow the geometry of the site to optimize column grids, basement car-parking layouts, etc.
- 14. • Some built form shaping adjustments or shading devices (e.g. balconies) may need to be provided for those site locations which lie further north or south of the Tropics. • Generally the window openings should orientate north-south unless important views require other orientations or openings.If required for aesthetic reasons, glazed curtain-wall may be used on the non-solar facing facades. • But on the 'hot' east and west sides, some form of solar-shading is required making due allowance for glare and the quality of light entering the spaces. The west wall has the highest intensity at the hottest time of the day.
- 15. 4.RECESSES AND SKY-COURT One means of reducing the solar heat gain through windows is by shading the 'hot' sides of the building using deep recesses in the external wall. These may take the form of totally recessed windows, balconies or small- scale courtyards in the upper floors or 'sky-courts'.
- 16. 5.ATRIA, AIR-SPACES AND WIND-SCOOPS The use of multi-storey recessed 'transitional spaces' would represent another way of shading the 'hot' sides of a tall building. Atrium devices act as wind-scoops to direct natural ventilation to the inner parts of the building as well as for the exit of hot air resulting from the Venturi effect.
- 17. 6.THE OPEN GROUND FLOOR • It should not be enclosed nor air-conditioned so that it can effectively act as a transitional space between the hot outsides and the cooler insides. • Care should be taken, however, to keep out wind-swept rain and wind-turbulences at the base of the building. The ground floor of the tall building deserves special consideration. It should be entirely open to the outside as a naturally ventilating space.
- 18. 7.VERTICAL LANDSCAPING The introduction of planting and soft landscaping to the face of the tall building or integrated with its inner sky-courts in the building's upper parts can have aesthetic and ecological benefit as well as providing effective climatic responses.
- 19. 8.CONFIGURING THE FLOOR LAYOUT The building plan should provide humanity, interest and scale, as well as allowing for air- movement through spaces, the provision of sunlight internally, adequate ventilation, and so forth. These should be reflected in the building's configuration, in its floor- depth, the positioning of its entrances and exits, the provision for human movement through and between spaces, its orientation and in its external views.
- 20. 9.EXTERNAL MATERIALS AND THERMAL INSULATION • Roofs and walls in the tall building should be constructed of low-thermal- capacity materials with reflective outside surfaces where these are not shaded. • The roof should be of double construction, be provided with a reflective upper surface and also a ceiling of highly reflective upper surface. The use of a good thermal insulation layer is recommended. • External materials used might be those that are effective heat-sinks (e.g. aluminium composites) or be designed to have a 'double layered' ventilating space The radiation component consists of incident solar radiation and of radiant heat exchange with the surroundings. The convective heat impact is a function of exchange with the external air and may be accelerated by air movement. Radiation and convective impact
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