The site before development started
Level 3 bridge area
Shell Beams
Structural and services engineers worked hand-in-hand with the architects to plan Auckland University's $25 million Population Health Complex under construction at its Tamaki campus.
The site before development started
Level 3 bridge area
The 11,000 square-metre, four-level building incorporates many sustainable design features resulting from the work of Project Architect Carsten Auer of Architectus Auckland, Peter Boardman FIPENZ of Structure Design and Dave Fullbrook of Connell Mott MacDonald (CMM). Building work by Fletcher Construction began in November 2002 and is due for completion next January.
The complex will provide space, facilities and information re-sources to support postgraduate learning and research in medical and health science disciplines. There will be accommodation for the School of Population Health (Faculty of Medicine), Optometry, Speech Language Therapy (Faculty of Science), and various general and specialised clinics.
The design team's objectives, reflecting the wishes of the client, were to:
The integrated design effort aimed to combine structure, facade, heating ventilation and air conditioning systems, services distribution, ceiling surface and thermal mass to achieve temperature stability.
COP Outcome development and evaluation
A feature of this approach was an innovative use of shell beams, manufactured by Stresscrete, to achieve a high level of passive environmental control. The exposed shell-beam flooring provides thermal mass to stabilise temperatures in occupied spaces, increasing passive solar heating and reducing night time cooling in winter, and encouraging overnight pre-cooling in summer.
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Design
Level 4 prior to roof
Internal wall framing being installed on level 1
Project sponsors visit the site
COP Outcome development and evaluation
The air conditioning/mechanical ventilation system also uses the shell beams to distribute air, which is returned via the building cores or a main atrium. The potential for free cooling to high-load areas and for energy efficiency have been maximised.
Stresscrete Professional Services Manager Keith Norgate MIPENZ says that the shell beam arrangement combines a number of building functions and technologies into a single high-performance structural; element. The result is a long-span column-free structure serving 12 metre floor plates, incorporating air supply and extract channels, cable management provision at floor level across the floor plates, a ceiling surface and a stabilising heat sink and source of thermal mass.
In a novel use of these major structural elements, the shell beams, for the complex were manufactured with smooth interiors and installed at close centres to conduct services and air-conditioning ducting.
Another novelty is the use of exposed radial shell beams and infill panels to satisfy architectural requirements, allowing the floor to run smoothly around the curves of the building. Several hundred of these precast beams, each weighing around three tonnes, were delivered to the building site in Glen Innes and lifted by a big Favco tower crane for placement under the supervision of main contractors Fletcher Construction.
This was an unusual project because the beams were exposed, and also because of the sheer number required by their air conditioning role – probably two to three times as many as would normally be used on a project like this. Placement was a time-consuming and painstaking task. Fletcher's Project Manager Mark Ritchie says, "From the constructor's point of view the shell beams were very special and had to be handled with great care. Those with plywood infills needed to be checked for quality control, and each beam had a unique identity."
The plan form of the building has been developed to encourage the use of natural light and ventilation. The large floorplates are linked to the atria and courtyards to provide an optimum balance between space planning, natural ventilation and daylighting provision.
Courtyards act as sunny summertime meeting spaces while the main atrium provides a similar sheltered facility in winter. The atria also promote natural ventilation, utilising the stack effect from temperature differences and venturi effect from the airflow across roof outlets.
Construction
Concrete floor being poured.
CMM's Dave Fullbrook says that the building concept is based on the idea of a filter, acting to control the adverse effects of sun, noise and wind. It comprises a biofilter of deciduous trees, a facade articulated with sunscreens, and a building form offering wrap around protection."This approach develops the building with active spaces to the front and sheltered spaces suitable for passive control behind."
COP Outcome development and evaluation
An efficient building fabric with good levels of thermal insulation, and sunshading and lightshelves at the external perimeter, should minimise heat losses in winter and heat gains in summer, while maximising outside awareness and daylighting and controlling glare.
"We're also seeking to provide an excellent working environment to encourage high levels of health and productivity by virtue of good air quality, thermal comfort, daylighting, outside awareness, personal control and space planning," says Mr Fullbrook.
Significant cost savings were anticipated from effective natural climate control and innovative ventilation strategies, despite the large numbers of computers expected to be in operation in the complex. The aim is to provide a "long-life, loose-fit and low energy building" with an appropriate balance between capital and operating costs, suited to university use.
Architectus (with CHS Royal Associates) used the same integrated planning approach working with Mr Fullbrook (then at Arup Associates) and Mr Boardman (then at Holmes Consulting) on the award winning Mathematics, Statistics and Computer Sciences building at Canterbury University.
Outcome
The main crane
This 11,500 square metre building featured:
Mr Boardman explains that both of these projects required a floor system that satisfied the architectural constraints and could accommodate a column-free structure, air supply, cable reticulation, ceiling surface and thermal heat sink.
COP Outcome development and evaluation
The solution devised for the Auckland project was a variation on what was achieved at Canterbury, using off-the-shelf products as much as possible, and employing shell beams in a "completely new way." The Canterbury building cost significantly less than budget, and is less expensive to run than a typical university building of its size.
The building won the NZIA National Award for Architecture and the ACENZ Gold Award for Engineering Excellence. A Probe (Post Occupancy Review of Buildings and Engineering) questionnaire determined that the level of satisfaction among its occupants placed the building among the top five percent of buildings surveyed.
Mr Norgate said expectations were high that the success of the Canterbury project would be replicated in Auckland. He points out that the project brought together representatives of three different design disciplines – "a structural engineer who understands precast, an architect who appreciates the form of the structure and a services engineer who has enhanced the utility of the structure" – to find a novel and integrated design solution.