Eco couple keep their sunny side up

GAUTENG couple James and Dorris Forbes would not call themselves eco warriors. But their estimated R29-million "green" home on a 6384m² property in Lanseria, northwest of Johannesburg, is an environmental marvel.

The six-bedroom house runs entirely on solar electricity, generated by 24 roof-mounted solar panels.

The grounds feature a pond holding 160000 litres of rainwater that is used for irrigation during the winter months.

The home has thermal insulated walls, double-glazed windows and doors, hot-water underfloor heating, special coolers that emit fine sprays of water, and 24 batteries for storing generated power. Even the decor - such as the glass chandelier, white-washed wooden coffee table and wall panels in the bar - was made from recycled material.

"This is not new for us. Green living is common practice in Europe. It was horrible for us to live here between concrete walls, so we had to design a home we would be more comfortable living in," said Dorris, who hails from Germany.

Forbes, a British businessman who moved to SA with his wife eight years ago, said the trick to having this kind of house was to ensure comfort while giving thought to using materials that allow the home to run without a huge demand for electricity.

So he insulated everything, from the walls to the building slab.

"All the walls have a 10cm gap between them, into which insulating thermal material called rock wool is filled, which is excellent for blocking sound or heat."

Large awnings and wooden shutters incorporated into the roof design keep out the midday sun.

"To enjoy the scenery and indoor-outdoor lifestyle so typical of the Highveld, the shaded overhang and shutters, coupled with double glazing throughout all the doors and windows, enabled us to create a very light-filled environment, which also gives us constant temperatures throughout the year."

He runs 24220W solar panels on the roof, sufficient to power everything inside.

"We generate up to 34kW of power each day and can operate perhaps two weeks without the benefits of Eskom."

Evaporative cooling systems draw in air from outside and pass it through a spray of water. The water then evaporates and cools the air, which is blown throughout the house like an airconditioner.

All the couple's domestic hot-water needs and under-floor heating are provided by heat pumps, powered by the solar panels.

Forbes said it took 15 months of planning and research - and another 18 months of building - to create their eco masterpiece.