SUSTAINABLE LOW-RISE BUILDING
- A Case Study
Telecom Place, Auckland, New Zealand
A spectacular new energy-efficient office campus on Auckland’s Victoria Street West, will provide a new head office for Telecom.
All 29,000m2 of the rentable area of the Mansons TCLM Ltd development will be leased by Telecom, who will relocate more than 2,500 staff into the purpose-built head office in 2010. This move will bring together its fragmented Auckland workforce in a modern open plan layout.
Comprising four office towers joined by a central atrium with connecting walkway bridges, the buildings sit on a podium containing three levels of underground parking and plant areas.
Culum Manson of developer Mansons TCLM said, “Taking an organisation and spreading it over a low-rise campus style development with a large floorplate creates greater interactivity between employees than a high-rise design”.
Given the low-rise design, it was desirable that height was used as economically as possible.
Height savings were made, without compromising stud height, by using an innovative new system of reinforced concrete floor beams.
Each beam is 1200mm wide but only 425mm deep, with a prestressed steel strand in the lower portion of the beam. This results in an extra floor being achieved when compared with using standard floor beams throughout the height specified.
The floor structure is predominantly Double Ts with deep precast flat slabs around shear wall and core areas. In-situ topping slabs tie it all together. A combination of precast panels and in-situ (poured onsite) concrete will be used in construction of the building's walls. The columns throughout the structure are in-situ concrete.
The ready mix concrete plant in Avondale has provided the majority of the 5000 cu m of concrete supplied so far.
Many challenges were presented in the initial stages of the construction, with 48,000 cu m of soil needing to be excavated to make way for six 200 cu m basement pours completed during October, November and December 2008.
These required some special project management when space limitations on site were combined with the restricted operating hours of the busy central business district location.
A significant amount of concrete was also supplied to Hauraki Piling who constructed approximately 300 temporary and construction piles for the project.
Auckland architects Architectus have designed a low energy façade using high performance double glazing. This has a low E coating and a good shading coefficient, which are achieved without blocking significant daylight.
Although primarily an aesthetic feature, the façade has aluminium fins which provide solar shading without interrupting the view, control solar heat gain in summer, limit heat loss in winter, and improve thermal comfort. This minimises the energy used by air conditioning.
The atrium is the focal point for the development, with link bridges and atrium base providing a visually interesting space for general circulation and informal meetings. It also opens the building to plenty of daylight and offers a view through to other areas of the building.
Consulting engineers, Beca, have designed energy efficient building services without compromising on comfort or the standards of flexibility and quality that are expected in leading CBD offices.
An innovative approach to air conditioning involves a unique passive “chilled beam” system. The metal ceiling is used to deliver 35% of the cooling radiantly. This reduces draughts and allows occupants to feel cool, even at higher air temperatures.
The chilled beam system was selected after consulting several air conditioning specialists and visiting 50 buildings in Australia.
“The system is the first of its type in New Zealand and was extensively tested with laboratory mockups to prove its suitability. Fresh air will be supplied at 2.5 times the building code minimum, providing people with a very high level of indoor air quality,” said Gary Young, Construction Manager for Mansons TCLM.
Tailoring the level of air conditioning to suit the degree of usage of any particular area is made possible with a microprocessor control that monitors air quality in each area, using CO2 sensors. Temperature and humidity is also measured and the controller then calculates and delivers the optimum amount of heating, cooling or fresh air.
Artificial light is provided on the basis of the degree of need as opposed to through an arbitrary on/off switch.
Computer controlled lighting, monitored and controlled locally or from a PC workstation hands control over to the occupants.
Daylight sensors save energy by dimming perimeter lighting when it is unnecessary, and the division of lighting into small individual control zones means the only lights in use are the lights needed.
Occupancy sensors in meeting rooms and offices, act automatically on entry and the lighting control in main meeting rooms is linked to the audio-visual system, dimming lights and closing blinds when in use.
Low energy lights fitted throughout include the latest T5 fluorescents equipped with flicker free electronic ballasts and low energy LED floodlights in the atrium. “LED lighting on this scale represents a large initial capital cost, but given the exceptionally low running expenses, this outlay is quickly recouped,” said Gary Young.
All plant within the building as well as energy and water usage will be monitored by a computerised building management system, via an extensive network of meters.
A sophisticated fire detection and alarm system will activate sprinklers where needed. Office floors normally open to the atrium will be sealed by automatic smoke curtains.
To exploit the building’s central location, extensive provision of dedicated showers, lockers and cycle racks for the building’s population has been made to encourage cycling and foot commuting.
Small cars are favoured in dedicated parking spaces.
Telecom will also provide numerous video conferencing suites to cut down on corporate travel.
Low water usage taps, showers, WCs and urinals will reduce water consumption. Toilets will be flushed by water provided by a rainwater harvesting system that collects rainwater from the roof. High water usage in any one area will be detected by a building management system.
Wherever they are available, sustainable materials will be used – including low environmental impact carpets, non-carpet floor coverings and insulation, CFC free insulation, recycled steel and low VOC paint, carpet and adhesives.
A five star office Design NZ Green Star rating is targeted with Beca appointed as Green Star accredited professionals to advise on environmentally sustainable design issues throughout design and construction.
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