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Load shedding has become commonplace in South Africa, but while daily conversation is about alternative power sources, it does nothing for the bigger picture. We are running out of power and we need to make real changes, fast.

But where to begin? Kerry Henning, marketing manager, Saint-Gobain, says that sustainability is not a choice. With predictions that the energy crisis will be here for at least another five years, water supply becoming a challenge and building costs on the rise, the picture is dismal. “Often we can build the home of our dreams but are unable to live in it or afford to maintain it,” says Kerry.

The Wintertest Campaign

Saint-Gobain recently ran a campaign titled #Wintertest. A leader in innovative solutions to habitat construction, it built Stand 47 on Monaghan Farm in Johannesburg and invited people to spend a night in the house in the dead of winter. Built from energy-efficient materials, Stand 47 requires no mechanical heating or cooling, and is designed to conserve resources and reduce waste while not compromising on comfort. For instance, it incorporates drywall and ceiling systems that are warm to the touch and assist in insulating the home.

Living Green

It seems that Stand 47 has exceeded expectations and demonstrated that sustainability in residential property is achievable. Says architect Natus Viljoen, world-class manufacturer facilitator at Donn, “Staying in the house changed my mind about living green. You don’t need all these perceived luxuries of heaters, air conditioning and fans. At Stand 47 the insulation was done correctly by using the right material for the application. What a difference it made, as it was very cold the night we stayed and the inside of the house was so comfortable that we didn’t even feel the need for a heater. That is sustainability.”

Becoming Sustainable 1

How to make your Home more Green

The first step is to analyse your current home, its sustainability and what you can begin to look at changing. Henning points out, for example, that in winter a home can lose up to 35% of its energy through an uninsulated roof and will gain the same amount of energy in summer. “By adding thermal insulation in the design of low-cost housing, or retrofitting a ceiling with insulation in a home without thermal insulation, it is possible to save up to 78% of a home’s energy consumption for heating and cooling, as long as one implements additional energy-saving techniques,” she says.

Begin by looking at the design of your roof and ceilings, as this can account for 25% to 45% of heat gain or loss. A properly insulated ceiling can cost less than 1% of the total per-square-metre building cost, says Henning. And if you are fortunate enough to be building from scratch, you should realise that homes no longer have to be built from bricks and mortar. Using simple, sustainable design principles will help to overcome energy challenges.

Did you know?

Outer walls in a house can account for up to 30% of heat loss and gain.

Insulation costs

  • Isover geyser blanket – about R230
  • Think Pink Aerolite ceiling insulation – about R52/m2 for material
  • Dry-lining wall insulation – between R120/m2 and R350/m2

(All costs exclude labour.)

How to build for energy efficiency

  • Windows: a single pane of glass can lose almost 10 times as much heat as the same area of insulated wall. Consider installing double-pane, low-emissivity (low-e) coating glass to reduce the transfer of heat through the windows. Low-e coating is available for high, moderate or low solar gain.
  • Reduced window-to-wall ratio: the correct balance between glazed and wall surfaces in the external facade maximises daylight while minimising unwanted heat transfer, resulting in reduced energy consumption.
  • Shading: external shading devices protect windows from direct sunlight that increases both solar heat gain and glare. Designs that take advantage of summer and winter sun should be considered.
  • Ventilation: a natural ventilation strategy can improve the occupant’s comfort by providing both access to fresh air as well as reducing the temperature. This results in a reduction of the cooling load, which lowers both initial capital and maintenance costs.
  • Heat pumps: used for heating water, these use electricity to transfer heat from the air to water in a tank rather than generating heat directly.
  • Lighting: using CFL (compact fluorescent lamps), LED (light-emitting diode) or T5 lamps helps to reduce a building’s energy use on lighting. Heat gains are lowered, which in turn reduces cooling requirements. The service life of these types of bulbs is generally higher than regular light bulbs, so maintenance costs are reduced.
  • Solar: photovoltaic (PV) panels help reduce the amount of electricity drawn down from the national grid. PV panels unlock the latent potential inherent in every building’s roof space to generate clean, renewable energy from the sun.
  • Gadgets: unlike conventional meters, smart meters help to reduce energy demand by raising the occupants’ awareness of the amount of energy they’re consuming. This can result in 10% to 20% energy savings.



Words: Claire Barnardo

Images: Supplied

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