A mega-scale development at the heart of the megacity in southwest China, Raffles City Chongqing comprises a shopping mall and eight towers for residential, office, serviced apartments and hotel use. The Crystal, the most eye-catching ‘horizontal skyscraper’ of the development, contains multiple dining and event spaces, a hotel lobby, and a members-only clubhouse with an infinity pool.
In close collaboration with the client CapitaLand, WSP tailored our innovative MEP and vertical transportation system solutions for this largest ever Raffles City development in the world.
MEP Tailored for the Vessel
Inspired by traditional Chinese sailing vessels, the curvature of towers imposed certain challenges to our design for MEP transitions with minimal impact to internal usable floor area, with MEP risers offset time to time to suit the structure. We also made use of detailed spatial planning by BIM to allow adequate space for MEP transitions at design stage. Off-site pre-fabrications were adopted to ensure construction quality and accuracy.
This feature also impacted our tower vertical transportation design. Instead of direct lift provisions, shuttle and transfer arrangements are required to minimise lift shaft space and allow flexibility in functional demarcation, such as the office levels at the low zone and the serviced apartments and hotel at the high levels.
Realising the Exceptional Skybridge
The Crystal is straddled on top of four 250m-tall towers, with link bridges connected to hotel guestrooms and residential units in another two 330m towers with 500mm anti-seismic joints. We designed a special MEP installation detail on bearings to allow movement of services crossing these seismic joints in three dimensional directions.
Its upper portion for front of house programmes is enclosed by structural steel with 50% metal and 50% Triple Low-E glass panels. To prevent over-heating, transparency of glass panels varies from low level at roof to high level when approaching occupied level. To achieve conservation of energy, underfloor cooling system is adopted with CFD simulations to ensure thermal comfort of occupants. Dual purpose extraction fans were installed to discharge cumulated hot air at the top during normal operation or act as smoke extraction fans in case of fire.
The lower portion of The Crystal is mainly for back of house operations. Due to limited space and headroom, we utilitised BIM to optimise the structural beams, refuge area and MEP spatial requirements to ensure effective evacuation of people from the sky deck.
Optimising energy-efficiency
This project incorporates advanced district cooling and energy efficient systems designed by WSP, supported by a highly reliable power supply with dual and standby power sources. We planned an efficient services distribution across the development with chiller plants located at the center of the project and transformer rooms at the bottom of each tower to minimise energy loss.
The integrated energy management system covers the entire development, which includes a chilled water supply system with the temperature adjusted for the different requirements of the hotel, offices and landscaped areas for effective energy saving. Chillers and cooling towers of the project are divided into two independent plants with inter-link to enhance overall reliability. We also utilise the large temperature difference to save pumping energy consumption, with a thermal water storage system to enhance overall system reliability.
With other environmental-friendly designs such as demand ventilation control and skylight with water cooling, Raffle City Chongqing has achieved LEED Gold pre-certification, setting the standard for future mixed-use supertall buildings.
