Future perfect

Heightened awareness of green building practices from responsible developers ups the game of suppliers and contractors, the expectations of tenants and, at the other end of the chain, investors. The knock-on effect is that market forces will drive down the cost of energy-efficient materials, designs, and technologies enabling sustainable building construction to quickly be offset by attendant energy savings. In physical terms there are two clear winners one, the office worker sitting in an optimistic, healthy environment, and the other, our fragile Earth.

The environmentally focused Green Square project, developed by Leighton Properties, is the largest mixed-use corporate office park built in Brisbane in the past 15 years. Green Square is designed to accommodate more than 40,000m² of A-Grade commercial office space over two tower blocks, with high-tech industry and community facilities, a retail plaza and residential precinct all part of the makeup. The project forms an integral step in Brisbane City Council's ongoing Urban Renewal Plan.

Green Square South Tower includes 17,000m² of office space over five levels, 360m² of retail space with adjacent plaza and two levels of basement car parking.

With Green Square's South Tower office block completed and a 12-level North Tower currently under construction, the development is already setting benchmarks in responsible development, says Leighton Properties' development manager Nathan Anderson.

"The Green Square South Tower is the first commercial building in Queensland to be awarded a 5-star Green Star rating for Office Design from the Green Building Council of Australia," says Anderson. "The council also made comment that this is the most cost-efficient 5-star, Green Star project in Australia to date."

Leighton Properties aims to exceed these achievements with a 6-star rating on the North Tower.

To achieve these stamps of environmental approval the design of the Green Square buildings incorporates a variety of ecologically sustainable initiatives. These result in significant energy and water savings, improved indoor environment quality, minimisation of atmosphere emissions, and a reduction in the use of natural resources.

Environmentally responsible considerations for the Green Square office park also take in the bigger picture as seen from a town-planning perspective. Apart from the main buildings and plaza, the Green Square precinct includes mixed-use redevelopment of a former industrial site, and the creation of a multi-use infill linking to another significant existing precinct. Public transport is close at hand, encouraging car-free commuting and the office blocks have extensive bicycle facilities.

On an urban level, visual links between the office buildings will be created via a vertical planted wall extending up the North Tower's 12-storey face. This will flow into the South Tower's central atrium, conceived as an internal garden for the latter building.

It is through the energy-saving technologies employed that the development shines.

"Savings on water and electricity were both critical to the five-star agenda," says Anderson. "The Green Square South Tower design has resulted in estimated water savings of 33.8 megalitres per year."

One method of achieving this is rainwater harvesting. The roof of the South Tower is utilised to capture rainwater in a 90,000L underground tank, for later use in toilet flushing and external irrigation.

All mechanical condensate from the air conditioning system is also captured for toilet flushing and irrigation. The fire test water is recycled in the same way.

Green Square South Tower does not include conventional cooling towers. Instead, heat rejected from the tenant cooling loop is provided by insulated heat rejection units that require low water consumption, high energy transfer, and absence of chemical usage.

All hand basins, showerheads, WCs and urinals are specified to a minimum AAAA rating.

Air-cooled chillers, while less energy-efficient than water-chilled coolers, were also selected to avoid water consumption. Fans and pumps were specified to compensate for any efficiency shortfall. The air-cooled chillers specified for Green Square are, relatively, high-efficiency units, utilising micro-channel heat exchangers and high-efficiency rotor compressor units. Swirl diffusers induce a greater air movement, while saving energy.

Energy savings of over 410,000 kWh per annum and CO2 reduction of around 390 tonnes per annum are also forecast for the South Tower. This reduced drain on power bills and emissions is spread over several fronts.

Approaches include energy-efficient lighting design, with high-efficiency single T5 fluorescent light fittings on a widely spaced grid. This lower lighting density results in half the energy use of a conventional lighting design.

The project also uses high-efficiency electronic ballasts. These produce less heat that traditional iron-core ballasts, reducing the load on the air conditioning plant.

Making the light switching zones under 100m² allows the building user to switch areas of the lighting off when natural light is available or when part of the floor is unused for a period of time, or after hours.

Throughout the building, CO2 sensors are used to determine the approximate population density. This information is used to increase or decrease the outside air delivered to the building while using the least energy possible.

Lastly, and significantly, every window pane and facade angle contributes to the energy-saving agenda. Reduced heat load on the building is achieved by a combination of form, orientation, external shading, rationalisation of glazing and choice of insulation.

"Green Square South Tower works hard on every conceivable angle to minimise drain on the national grid and optimise the working conditions of all who work under its optimally angled roof plane," Anderson says.

For details, contact Leighton Properties, phone (07) 3229 8938. Websites: www.greensq.com.au and www.leightonproperties.com.au.

The desk worker sitting comfortably in a well-lit, well-ventilated office, free of toxins, is likely to be a happier, better-performing member of staff. For employers, this quickly translates into increased productivity and increased end-of-year margins.

The human element is vital to a shift in consciousness for a greener world. This might apply to everyone from a subcontractor finding ways to further the nothing-wasted aspect of a fit-out, to a concrete supplier realising that supplying an environmentally friendly product might soon shift from a concept to a business imperative.

If Leighton Properties was the driving force behind a project that leads Queensland in environmentally responsible development, then Leighton Contractors was the force that made it all happen. Leighton Contractors has overseen the design, consultation, construction, and rallying of subcontractors, says building operations manager Greg Muir.

"The Green Square team has incorporated significant environmental benefits into the construction phase, through careful material selection and rigorous waste management," Muir says. "This green ethos applies from the bones of the construction out literally. 90% of the steel used for the office towers has a recycled content. The stronger the demand for eco-responsible materials, the greater the competition and in turn the more affordable the green alternatives become."

A prime example of this was the award of the concrete supply on the South Tower. This was based primarily on the suppliers' capacity to provide a mix that replaced 40% of the cement material with flyash, an industrial waste product, whilst maintaining workability and quality. Only one supplier could meet demands for this product in a commercially effective manner when the South Tower concrete supply was up for tender.

However, a year later, when work on the North Tower commenced, three further companies were able to supply the right mix at commercially competitive rates.

"Feedback from suppliers was that their inability to meet requirements of the South Tower specification, leading to loss of the contract for them, was a strong driver in their move to develop a workable mix which reduces embodied energy and resource depletion," Muir says.

All other materials on the Green Square project came under equally close scrutiny. All of the timber was reused, recycled or Forest Stewardship Council (FSC) certified. This attention to material impact is seen in the South Tower's dedicated recycling room, for use by all tenants. However, this is echoed in Leighton Constructions' own good construction practises.

"Waste management procedures ensure that 100% of waste generated during construction is diverted from traditional landfill," says Muir. "Waste concrete, steel and cardboard are separated for recycling and all remaining general waste is transported to a bioreactor facility to generate renewable energy."

With the 5-star Green Star rating already under its belt for Office Design, the Green Square project team is also targeting a 6-star rating for As-Built and Office Interiors. This requires a rigorous measurement of everything from recycled content in materials to the zero-emission level requirements of finishes and the correct user-friendly light lux levels over any given area.

Together with considered urban planning, green architecture, energy-conscious technologies and use of responsible building materials comes another important aspect of the project a shift in consciousness at human level. Extensive education has been provided to all project participants, including induction materials, educational posters on the sustainability aspects of the project and an ESD section in the project newsletter. Formal education was also available through the Green Star Accredited Professionals Course, and the site has had an open day where industry professionals and visitors could see the responsible building practices of Leighton Contractors and the sub-contractors in action.

"At a grass-roots level, the excitement of creating such an eco-responsible building has caught everyone's imagination," says Muir. "One worker came up with the idea for capturing water for reuse in dust suppression. Another contractor suggested a compost facility be introduced for workers, and now there is even a worm farm set up both of these facilities now benefit the trees of an adjacent school."

Green Square office park is not only set to live up to its name, it literally has nature at its heart. A central community area within the South Tower, known as the Parkland, links the two main sections of the tower, pouring natural light into the centre of the building.

"Facilities such as meeting areas are located within the Parkland to activate the space," he says. "The materials used on the Parkland reflect the greater project that surrounds it recycled timber seats, stone pavers, reconstituted timber veneers, raw concrete finishes and plantings characterise the space."

For details, contact Leighton Contractors, phone (07) 3215 4400. Websites: www.leightoncontractors.com.au and www.greensquare.com.au.

Story by: Trendsideas