The most conspicuously placed and shaped formal elements of the architecture, which is otherwise low-key and generic (and should prove immensely adaptable in the long term), are the towers that harness the wind to drive the internal ventilation systems.
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The buildings themselves are linked by a lakeside arcade, off of which open the atria that connect the classroom buildings. In addition to serving energy-saving functions the atria are, with the arcade, the main social spaces of the campus, which is also green in its social conviviality. The largest of these atria, which are also intrinsic to the energy-saving strategy, houses the main campus cafeteria.
It is significant that the campus is not out of town but within easy walking distance of the main campus and well served by public transport. In urban terms it defines an edge and buffer between the bigger buildings of the town center and the suburban houses beyond the lake, situating the scheme in place as well as nature.
The design, like that of most innovative green buildings, was a close collaboration between architects and engineers, in this case, Arup. The landscape design is by Battle McCarthy, also renowned for their green engineering.
The site, half a mile from the lushly landscaped main campus, had been covered by factories. Where a stream ran before is now a lake edged by trees. These cool and filter the prevailing wind that drives the ventilation system of the new buildings lining the other side of the lake, where they are linked by a lakeside arcade.
The lake and landscape also shelter wildlife, while reed beds purify rainwater run-off. The landscaping extends to the planted roofs of the academic blocks. As now developed, the site makes an apt transition between the large buildings of the town center and the suburban housing beyond the lake.
The brick-faced blocks near the entrances to the site are student residences. The academic buildings are wood-clad. Projecting into the lake is the library, which spirals up as an inverted truncated cone on axis with a stack of auditoria. The auditoria intrude into one of the glass-roofed atria that separate the wings of the typical academic buildings.
The typical academic building consists of wings of rooms separated by atria that serve as thermal buffers between inside and out. The atria are naturally ventilated, drawing air in through their scoop-shaped lake fronts and exhausting it on either side of the stair towers.
With their plant rooms capped by rotating wind cowls, these are major elements in the wind-driven, mechanically-aided ventilation system of the academic rooms. The cedar cladding — from sustainably managed forests — was chosen as a replenishable material of low-embodied energy, and galvanized rather than stainless steel is used throughout because it is lower in embodied energy and less polluting to manufacture.
In the plant rooms over the stair towers and below the wind cowls, fans, a heat exchange wheel, an evaporative cooler, and louvered dampers switch air through bypasses. They work in four primary modes according to season and time of day. In peak summer conditions, it is the exhaust air that is cooled before passing through the heat exchange wheel. In this way, incoming air is cooled without humidification.
The academic rooms are naturally ventilated for much of the year and ventilated by the wind-driven mechanical ventilation system during hot and cold periods. To be driven by the wind, with assistance only from low-powered fans, the whole ventilation system is designed to entail minimal friction and pressure drop.
Intake air is admitted just below the exhaust cowl and blown down big ducts on either side of the stair shafts. From here it is guided into under-floor plenums from where it enters the rooms. It is then drawn out over sound absorptive material above the corridors, so as not to compromise aural privacy, before descending into the corridor.
The air is sucked back along the corridor to the stair shaft and up and out by the wind blowing past the cowl. On hot still days when there is insufficient wind to drive the system, photovoltaic cells shading the atria roof provide the electricity — indirectly, since it is fed into the national grid — to drive extract fans.
Wooden louvers exclude direct sun, while their white upper surfaces reflect light deep into the rooms. Nighttime lighting is by high-efficiency fixtures that provide up and down lighting from the same light source.
All the above has been achieved with buildings that cost only $105 per square foot. This proves that even architecture that exemplifies all ten shades of green need cost no more than conventional buildings, yet will bring huge cost savings in the long term.
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Peter Buchanan is an architect, writer, critic, and consultant in environmental design and planning, living in London.
This article is excerpted from Ten Shades of Green: Architecture and the Natural World, copyright © 2005, The Architectural League of New York, available from W.W. Norton & Company and at Amazon.com.