Many existing trees were also retained, and the use of water-permeable paving blocks for exterior walkways allows rainwater to seep through into the soil and back to subterranean aquifers.
Each house was designed to take advantage of natural light and to enjoy views across the valley. To achieve this, houses are oriented to face south, with most living areas on the upper levels. Full-height windows stretch the length of living rooms.
In spaces where large windows did not suit, natural light and air come in through tall, narrow windows, slit windows in the ceiling, or via windows that open onto internal courtyards.
Cross-ventilation, a traditional technique sadly neglected since the advent of air conditioning systems, is another simple design feature that helps keep the homes cool and airy.
External insulated rendering, which adds little to construction costs, reduces heat loss in winter and lowers energy consumption year round. Other features that reduce energy consumption include double glazing, louvres to control heat and light, and south-facing solar panels.
Inside, walls, floors and other surfaces use sustainable materials, such as prefabricated, structural bamboo which takes only four years to grow and costs less than concrete and lightweight steel studs, also prefabricated off-site.
"While some of these techniques may seem to add a small cost to each home, many do not, particularly when they are incorporated in the initial design stages. Reduced electricity bills also offer ongoing savings," says Bruce.