On the outskirts of Ixopo, in the KwaZulu-Natal midlands, the Sisonke District Office for the Department of Public Works was the first government building to receive a 5-Star Green Star SA design rating. The office embraces sustainable design principles by addressing energy, water, waste, transport and indoor environmental quality issues to ensure comfortable, healthy indoor spaces as well as a lighter environmental footprint.
The office building is long and narrow with north-facing orientation as the important first step towards greening. The building uses locally sourced materials including face-brick, timber, insulation boards and aggregate for the concrete.
The building reduces energy consumption through natural lighting and ventilation and does not require mechanical air conditioning. Heating and cooling is via underfloor water pipes and an energy efficient heat pump. Solar water heaters provide hot water. High efficiency lights are fitted with motion sensors and electrical sub-metering allows the building operator to monitor energy use.
Water efficient fittings save up to 70% of water consumption and sub-metering allows for monitoring of water consumption. Rainwater is harvested for flushing toilets and washing cars and reduces the run-off from hard surfaces during a storm event.
Walking and cycling to work are encouraged and cyclist facilities are provided, including bike racks, lockers and showers.
Above the building
The extensive roof garden is planted with over 70 endemic species that only require a thin layer of soil to grow thereby reducing the structural requirements of the roof. Besides insulating the offices below the roof gardens bring a significant biodiversity boost to the area and contribute to the slowing of storm water run-off.
The site was previously overgrown with invasive alien vegetation and has been landscaped using local indigenous plants to return it to its endemic Natal Mistbelt grassland habitat.