Architect: Suraksha Acharya – Midori Architects
Client Name: Skyhive Skyscraper
Location: Kai Tak, Hong Kong
Project Type: Mixed Use Tower
Size: 1884717 sq.ft (175096 Sq.m)
Awards: SKYHIVE Skyscraper Challenge, 1st place ; A’Design Award & Competition, Silver Winner
Aero Hive is a breathing entity. The breath of this building transpires through vertical diaphragms in the form of green sky atriums that behave as lungs, performing the intake of oxygen and removal of carbon dioxide. This exchange is a way of natural ventilation and is the preferred option when attempting to deliver fresh air to any space due to its low energy requirements. The wind flow to the indoor spaces is carried using wind-scooping and the ‘venturi’ effect through the traversing green diaphragms that are oriented facing prevailing winds.
Aerodynamic architectural design is realized by taking into consideration building orientation, position, form, and plan variations. An algorithmic process of designing has been followed by creating a differentiated array of a hexagonal floor plates that variably changes scale based on environmental criteria, functional aspects, structural logics and aesthetic parameters. Computational modeling and environmental testing, namely, solar insolation and CFD analysis were carried out to verify the climatic effects of twisting geometries. Key to these forms of adaptation is the relationship of the building to their environment and the contextual forces that shape the form development and environmental behavior.
Aero Hive aims to challenge the common belief that contemporary tall buildings cannot be ventilated naturally due to their height and offers pause from the typical hermetically sealed glass-boxes, serving as a model of sustainability.
The site is located at Kai Tak area of Kowloon, Hong Kong. Following the relocation of Hong Kong International Airport from Kowloon City, this area was envisioned to be redeveloped into a distinguished neighborhood. Environmental factors and structural concepts shape the form and skin of this tower. A study showed that twisting the tapered hexagonal form 90 degrees clockwise and anticlockwise yielded self-shading benefits. The towers are positioned such that they shade each other at different times of the day. By carefully incorporating the natural wind patterns of the site, the building is designed to accommodate changing wind conditions. The three wind scoops on each tower anxillary and efficiently captures the moving air into the rotating Sky Atria – which is then transferred throughout the floor using large plenums. Aero Hive uses scooping for air intake with the help of hexagonal arms that function as wing walls and allows air to exit through operable windows or adjacent Atria.
A central triangulated core anchors each tower that arises 290m above ground level carrying a twisting form which is encapsulated by a triangulated exoskeleton articulating a multi-storey atrium leaving clear floor plates for functional distribution. The rotational and scaling aspects of floor plates around the central cores create a folding form that creates an amorphous geometry with atriums. The dynamic looking towers connect at three distinct levels with structural bridges formed by triangulated trusses.
In wind climates like Hong Kong with very directional extreme winds, building shapes that are directionally sensitive are more effective. The results from the CFD simulation on different shaped buildings showed that the circular shape had the lowest wind pressure coefficient and the square had the greatest wind pressure coefficient. Having a spectrum of different shapes in mind, an analysis showed that the hexagonal shape has an efficiency of 90%. In addition, along with advances in visco-elastic materials like tuned mass damper as well as structural systems like diagrid. To drive the natural currents to enhance air volume, pressure differentials between windward (up-wind) and leeward (down-wind) faces of a building were analyzed using CFD.
The building has been optimized such that sunlight will be carefully controlled, avoiding direct solar heat. Each three-story semi enclosed atrium contains office spaces on either side of the exterior hexagonal arms. The green areas are not only recreational but also protects from strong winds and avoids glare within office spaces. In the workplaces, the double-glazed windows’ skin opens inwards at the top with an angle of maximum 15°, thus allowing fresh air to move indoors. When the natural ventilation strategy cannot be applied due to extreme weather conditions, mechanical systems help ventilate the building.
Aero Hive’s aerodynamic architectural design plays a critical role in mitigating the “wall effect” caused by uniform high-rise developments. The flared roofline at the architectural top is designed to accommodate a Sky Park – a public green observatory that addresses the “urban heat island” effect island due to the combination of high-density, tropical climate and high-rise buildings. This creates a natural habitat, filtering pollutants and reducing CO2 content in the air while satisfying the aesthetic needs of a roof.
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