LOW ENERGY/HIGH PERFORMANCE

The single most effective way of reducing emissions of 'greenhouse' gases is to ensure that buildings consume only a fraction of the fossil fuel-derived energy they use presently­which constitutes nearly half the total energy consumption of the developed world. To make the drastic savings required, three strategies need to be applied: the whole form and organization of buildings should be shaped to be far less dependent on fossil-fuel energy; any mechanical plant should be as efficient as possible; and the building and its environmental systems should harvest and be fueled by constantly replenished ambient energies. Artificial lighting is a building's biggest consumer of energy, followed by air-conditioning. The use of daytime lighting can be reduced enormously, by abandoning the deep plan in multistory buildings, as well as by installing sensors that prevent lights being used unnecessarily. To let in lots of light, windows should be big; they then need to be shaded by overhangs, or by being recessed, so that high summer sun is excluded but low winter sun is admitted. Forsaking the deep plan also allows air-conditioning to be dispensed with in favor of natural ventilation, with the added advantage that this can be under the personal control of each building occupant. Even naturally ventilated buildings have to be designed to always remain within the range of comfort, however, and so may need occasional heating and cooling. In temperate climates the need for this can be greatly reduced, and sometimes eliminated entirely, by exploiting the thermal inertia of exposed heavy structures. These absorb large amounts of heat while warming up slowly, and then dissipate heat while cooling down equally slowly. Another increasingly common strategy is the double-layered facade, with a cavity sealed to form an insulating jacket in winter and opened to use the stack effect to draw cool air up it in summer. Double facades also allow windows in this inner skin to remain open in rain and at night when cool air purges heat from the structure. Careful design and devices of this sort will considerably reduce both the period heating and cooling that are required and the energy they consume, which in any case can be drawn from ambient energies and replenishable sources.

Buildings: Beyeler Foundation Museum, Commerzbank Headquarters, Cotton Tree Pilot Housing, Gotz Headquarters, Hall 26, Minnaert Building, Mont Cenis Training Center, Slateford Green, University of Nottingham Jubilee Campus, Cotulla Ranch House, Howard House, Palmer House, Westcott/Lahar House