Eco city in action

As we progress further into the new century, public awareness of sustainable design and construction continues to grow. However, persuading consumers to incorporate new techniques into their homes is a task that requires government and local government initiatives.

In Waitakere City, the city council decided the best way of educating was to lead by example. Over the past decade, it has been fulfilling a plan of developing Henderson, and the wider Waitakere district, into a vibrant, visually attractive area with civic and public buildings that utilise sustainable building methodologies.

The success of this vision can be seen in some of its recent developments: the soon-to-be completed Waitakere Central Civic Centre, the Waitakere Central Library/Unitec facility, Massey Leisure Centre and Library, The Trusts Stadium and West Wave. All incorporate architectural and engineering techniques to minimise the environmental footprint. Sustainability, however, is just one objective, says Waitakere City councillor Penny Hulse, chair of the City Development Committee.

"Looking at Waitakere City, Henderson was identified as the natural city centre by the other organisations that are indispensable to a fully-functional urban hub. Government departments have their offices here. All the main banks are here, as is the biggest retail operation, so the centre of local government should also be here," she says.

"All our new developments are investments in Waitakere's business, community and cultural heart. The city has grown over eight percent in just five years, compared to the national average of just over three percent, so developing the city to deal with growth is a priority. Exporting 60% of the future working population down the motorway every day is something we want to avoid. Creating a tertiary institution and stimulating the local economy will help contain and ultimately reduce those numbers."

The Civic Centre was designed by Architectus, in association with Athfield Architects. Artists Kate Wells and Matthew von Sturmer also played a key design role, ensuring that the art integrated into the buildings reflected the community.

"With the Civic Centre, our intention was to create an international best practice model of sustainable development. The project will eventually incorporate demonstration and education projects to help people visualise a more environmentally sustainable future," says Hulse.

Some of the sustainable aspects of the design include using renewable forms of energy, such as solar water heating. Maximum use of natural light was achieved with a shallow floor plan and appropriately located windows.

"Lights are one of the biggest energy users in office buildings and most employees prefer natural light. Efficient lighting with occupancy and daylight sensors ensure lights are only on when needed. Efficient lights also generate less heat."

Other energy-efficient techniques include the use of night time cooling, with air pumped through concrete floor slabs. These high mass materials effectively store coolness, meaning less energy is used for cooling during the day.

To manage storm water, a rooftop garden is planned to absorb and cleanse rainwater. This reduces flooding and water pollution in local streams, while also providing noise and thermal insulation and a habitat for birds and insects.

Working in tandem with the new Civic Centre in providing Henderson with a defined city centre, the Waitakere Central Library/Unitec, also by Architectus in association with Athfield Architects, is a modern three story library, learning centre and Citizen's Advice Bureau connected by a glass overbridge to a five-storey Unitec learning complex.

The Unitec structure includes flexible teaching areas with purpose-built computer and bioscience laboratories, a 180-seat lecture theatre and a student common room and kitchen facilities.

Ashley Barnett, design engineer from Connell Wagner who has worked on many of the council's sustainable developments, says different energy saving solutions were required for each structure.

"As a teaching facility, Unitec features varying degrees of occupancy. We used a Variable Air Volume (VAV) system with a control system that reacts to the loads of each space. As soon as anyone enters a room the central plant reacts accordingly, so we are always producing exactly what is needed."

With the library, a three-storey, mostly open plan space, the challenge was to use the building's mass to help control heat gain.

"In summer, cooling energy from the conditioned air is absorbed into the exposed concrete of the structure. The building's thermal inertia is slow, so in the morning the cooling load is low," says Barnett.

The library incorporates the latest in sustainable design features, including large windows at the western end for natural light. The sloping north-facing roof contains a solar water heating system, a north to south orientation makes the most of the sun for light and heating, whilst the building is also designed to minimise water and electricity use with dual flush toilets and flow restrictors.

Also conveniently located in Henderson are West Wave and Trusts Stadium, each invested with specific sustainable features. The West Wave aquatic facility features a wave pool, 67m hydroslide, lazy river, hydro-therapy pool and toddlers' pool. Environmental features include full solar water heating, natural lighting with double glazing, rainwater collection and water recycling.

The Waitakere City Council's aim to become an eco-capital of New Zealand extends beyond Henderson. The Massey Leisure Centre and Library has various eco features and art projects.

Outside the building solar power is generated, rainwater systems that purify and re-use water also double as water features, and permeable car parks cleanse and slow the traffic of rainwater.

Inside, most of the building is naturally ventilated. Cool air is drawn in from above the exterior water feature and further cooled before being discharged into the interior. These ducts can be purged with cooler night time air. In winter, an exposed concrete floor stores heat from the low altitude morning sun, releasing it throughout the day to supplement the under floor heating system. High levels of insulation prevent heat escaping in winter and overheating in summer.

A gas boiler accentuates water and space heating. Using gas directly is more efficient and causes less greenhouse gas emissions than electricity from a gas fired power station.

For further information, contact the Waitakere City Council, phone (09) 839 0400 or visit the website: www.waitakere.govt.nz.

Story by: Trendsideas