ArchSD Sustainability Report 2007

Case Studies / Case Study Two – New Radiotherapy Centre and Accident & Emergency Centre in Princess Margaret Hospital

[Case Study One – Stanley Complex] [Case Study Two – New Radiotherapy Centre and Accident & Emergency Centre in Princess Margaret Hospital] [Case Study Three – Restoration of Kom Tong Hall] [Case Study Four – Post Occupancy Evaluation]

Case Study Two - New Radiotherapy Centre and Accident & Emergency Centre in Princess Margaret Hospital

A new Radiotherapy Centre and Accident & Emergency Department replaced the previous Accident & Emergency Department (Block H) at Princess Margaret Hospital. Tailor-made to prevent and combat specific illnesses, the centre is designed to cater for radiotherapy, diagnostic radiology, clinical oncology and spontaneous treatments for accidents & emergency.

Providing over 22,000 m² of construction floor area in the building, which is located directly above a MTR tunnel, a major architectural challenge was to reduce the building composite weight to secure levels whilst maximising its height to 12 storeys. In addition to including a wide range of sophisticated medical equipment, the centre adopts modern green building design and technology. The result is an unrivalled stylish outlook within the hospitals building community, combining both functionality and sustainable materials.

Preserving green area in the hospital, the Centre is built on the brownfield site of the former Block H instead of a green field site. Since the site lies directly above the MTR tunnels at about 50m, extensive use of lightweight building materials is widely evident, whereby the use of steel plates sandwiched by concrete wall is selected as the composite wall design. The façade is mainly composed of an Unitised Curtain Wall, aluminium cladding, and aluminium louvers. The roof is metal and internal partitioning is made of solid lightweight concrete infill wall system.
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Through the reuse of the existing building fabric and the Unitised Curtain Wall System, construction and demolition waste can be largely reduced. Over 1,775m² of the former Block H are conserved and reused, while over 44% of external wall areas are covered by prefabricated unitised curtain wall panels to save waste generation.
The adoption of Light-weight Concrete Infill Partition System, substantially reduced construction waste and water consumption when compared with traditional blockwork through the saving of on-site concrete mixing. The System also performs better in sound and thermal insulation than block wall.
Internal areas are lit naturally by skylights. Energy used in artificial lighting is reduced and a more comfortable internal environmental can be achieved. Low-e glass is used to control solar heat gain through skylights.
Reduction of solar heat gain is evident with the use of low-e double glazing system windows, composite external wall panels, sun shading devices fitted outside all windows facing south, and over 409 m² landscaped garden.
Over 195 m² Building Integrated Photo-voltaic (BIPV) panels on roof canopies provide sun shading to upper floors and also generate 19 kW electricity which is adequate for general building use.
Energy saving installations such as Heat Recovery Chillers, Carbon Dioxide (CO2) Sensors for fresh air supply, and Occupancy Sensors for office lightings are installed to allow flexible adjustment in energy consumption, thus saving electricity.
Over 170 automatic sensor water taps are installed and each sensor tap can save 54% water when comparing with a normal tap. These taps also serve to meet modern infectious control standards.
To enhance hygiene protection, effluent of hazard materials (HAZMAT) is collected by an independent drain pipe system and temporarily stored in a fibreglass tank. The effluent is then regularly collected by a specialist company for further treatment before being discharged into a public sewer. In addition, activated carbon odour control device is installed to remove sewage treatment odour venting from drainage system, whilst allowing easy passage of surface water.
Contaminated exhaust air from laboratories and clean rooms is directed to roof level by 6 jet fans. Each jet fan can shoot contaminated air up to minimum 5 m high before dispersing into the atmosphere.
Vehicular and pedestrian circulation of this new building was carefully planned and re-aligned to improve the existing hospital traffic.