June 2000


Kadoorie Biological Sciences Building

Beneath the second skin

Overlooking the western entrance to the University of Hong Kong, adjacent to the library building, there now stands a gleaming mass of steel and glass which has become the home of three life sciences departments and the Institute of Molecular Biology.
To be used principally for laboratory research, the ten-storey Kadoorie Biological Sciences Building is the product of much research itself.
The process began in early 1996, when, after the Kadoorie family had decided to donate a building to the university, Leigh & Orange Architects was appointed to design and supervise the building's construction on a site adjacent to Pokfulam Road that was formerly occupied by the Chemistry Department.
Once the university had decided to assign the building to the Zoology, Botany and Ecology & Biodiversity departments for laboratory work, the process of determining user requirements began. First of all, though, Leigh & Orange had to face the challenge presented by a tight and difficult site.

Main staircase lobby - external view

Support structure
The building is sited in a geotechnically sensitive area with nearby slopes and large retaining walls. Appreciating that any additional loading could have an adverse impact on existing ground conditions, the architect sought to minimise the number of piles needed and came up with a solution which required only eight large diameter bored piles to be driven into the ground.

This solution resulted in the creation of an inverted pyramidal support structure with four columns tied to each pile to form a series of  "V" shapes at ground level. Circular columns formed by PG glass reinforced concrete permanent formwork were initially considered but gave way to fair-faced, rectangular columns due to the constructability preferences of the appointed contractor.
Since the building would be used for laboratory work, a high degree of stiffness had to be provided to ensure the safe and accurate operation of delicate instruments. This was achieved by the creation of two reinforced concrete framed structures, one for each set of laboratory suites, tied together in the central core by slabs and beams. Waffle slabs were used for the floor plates, both to reduce the building's weight and therefore its dead load; and to provide the lateral structural rigidity required.

The facade
The building was designed with seven key issues in mind, namely: functionality, flexibility, safety, energy efficiency, sustainability, lifetime economy, buildability and ease of maintenance.

All these considerations are reflected in all aspects of the building's design, particularly the facade. The Kadoorie Biological Sciences Building is the first building in Hong Kong to fully exploit the green possibilities of a second skin: an external glazed screen which is 2.5 m away from the external wall.
The building is clad in a combination of silver grey ceramic tiles and glass and steel double skin. The north and south facades are clad in ceramic tiles and the windows are protected by sunshading devices. External maintenance walkways surround the building at each floor level, providing safe and easy access for maintenance personnel. According to Leigh & Orange associate Gabrielle Tsui, the horizontal projections of the sunshade are calculated to strike a balance between solar control and daylight penetration to the interior.
The east and west facades are clad in a double-skin curtain wall which serves several functions. It acts as a screen for the building services installations distributed around the exterior of the building in order to provide a flexible interior for the laboratories. Having the building services installed on the exterior means maintenance can be carried out without disturbing laboratory users and laboratories are less likely to be contaminated. The security of the laboratories is further enhanced by the provision of access to the building services through external ducts and staircases.
The fritted glass used for the screen wall serves to limit solar radiation while the external services zone between the two layers of glazing acts as a stack which channels hot air upwards for discharge into the air, thus reducing the building's solar heat gain. An open metal grille installed at each floor allows free air circulation while serving as walkways for maintenance access. Heat gain is further reduced by locating heat emitting equipment in the external services zone outside the building, where they release their heat into the void rather than the interior.
The external glazed screens covering the east and west elevations are suspended by steel roof trusses. According to Ms Tsui, since the best structural capacity of steel is tension and not compression, it is more efficient to load the material through a tensile structure than as a rigid horizontal cantilevered steel structure which supports the screen on every floor. When wind load imposes on the glass, the loading is transferred via the bolts which hold the glass panels together to the vertical steel tubes and the bow string structure on the roof.

Short Section

The interior
The building provides 10,000 sq m of usable laboratory accommodation which features a range of innovations which planners of similar facilities here and elsewhere will be studying for some time.

To make the most of the space available, the architect brought in UK specialist laboratory planner Laboratories Investigation Unit to provide advice on laboratory planning and to be responsible for laboratory function design. With building services installations moved to the perimeter of the building, the interior space is completely freed up for laboratory facilities, which are served by a central core which, in addition to connecting the two multi-storey laboratory structures, also functions as a circulation core.
According to the architect, maximum flexibility and adaptability governed the design of the laboratory suites. Thought was also given to energy efficiency and waste reduction. Each suite is a 3 m high, 24 m by 24.6 m shell with smooth, flush and easy to clean surfaces. The suites are subdivided into 600 basic units using easily removable metal partitions which are pressure-fixed between the floor and the suspended ceiling.
Finding pressure-jacked partitions capable of providing the necessary rigidity was not easy. Similar partitions used at the City University in Hong Kong and the Lloyds Building in London were studied but offered little as both projects used partitions which still required mechanical fixing on one side, whereas the Biological Sciences building required top and bottom pressure-jacked partitions. Eventually the partition supplier, Clestra Ltd, developed a partition which offered the required rigidity and acoustic performance even with top and bottom jacking pressure support. Better still, at a thickness of 60 mm, it is also considerably slimmer than the partitions used in other projects, which are about 100 mm thick.
The partitions not only offer flexibility and rigidity, but also great functionality. Aluminium wall rail channels fixed on the partitions allow light switches, power sockets, shelves, cupboards, whiteboards and coat hangers to be simply hung while remaining movable. Smaller fixtures such as picture hooks and task lighting can be placed anywhere on a partition by using magnets. This provides further flexibility and adaptability to the need for change of usage in the internal space.
Services which enter the building vertically via a riser duct then horizontally into the external services zone are fed into the 1.25 m deep ceiling void on each floor. Flexible connectors distributed according to the 3 m grid allow all the services needed - water, gas, compressed air, electricity, telephone, etc - to be hooked up easily. Drainage points are also provided regularly on all floors to allow flexible internal space planning. They are connected where drainage is required; where it is not necessary, a cover plate is installed. The floor is paved with linoleum which, unlike artificial vinyl, is a natural, biodegradeable material.
The design concept of flexibility is consistent throughout, including the internal fitting works. The modular design extends to the laboratory benches, which are in the form of pre-plumbed/serviced spine units which can be bolted together in various combinations according to the layout.
A particularly green feature of the building is the use of recirculatory fume cupboards which only became commercially available recently. Developed by the British Atomic Research Authority, the fume cupboards utilise vortex fume scrubbing technology which, together with built-in carbon filtration, make them recirculatory, thus cutting down on the air-conditioning load of the building.
Since they are moveable, these fume cupboards also contribute to the layout flexibility of the laboratories. As they do not require a fixed rooftop scrubber and extractor, a whole floor of plant space was freed up, which allowed the architect to produce additional space to accommodate the Institute of Molecular Biology. The re-designed roof also accommodates greenhouses and an aquarium.
By locating heat-emitting equipment in the external services zone and using an external glazed wall as a sunshading device, without taking into account various other energy-efficient and environmentally-friendly design features in the building, the architect estimated that savings of 53,360 KWH of energy per year, or 2.67 million KWH over 50 years, can be achieved. Carbon dioxide emission is expected to be cut by 37.6 tonnes per year or 1.88 million tonnes over 50 years.
Built at a cost of HK$500 million, which includes the cost of demolishing the original chemistry building and site formation work, the Kadoorie Biological Sciences Building demonstrates that a green, intelligent building does not necessarily have to cost more than a conventional building.
Judging by the enquiries handled by the architect about this project, some in the private property sector at least may just be getting the message.

client The University of Hong Kong
donor The Kadoorie Charitable Foundation
architect Leigh & Orange
structural, civil, geotechnical, acoustic and fire engineer Ove Arup & Partners
laboratory specialist Laboratories Investigation Unit
main contractor Laing-Hip Hing Joint Venture
cost consultant Davis Langdon and Seah (HK)
landscape architect Hassell Ltd
external glazed screen Josef Gartner & Co (HK)

-- Building Journal