06 living
energy in question – you at home Exclusive extract from the book Bending the Curve, Your guide to tackling climate change in south africa Eskom is in chaos, electricity prices are going to go up, so what can we do about managing our energy usage in our homes? Here are top tips from Robert Zipplies book, one we highly recommend you read to get to grips with the complex issues facing us. the randS and SenSe of electricity uSage
When there’s another electricity cut at home, your frustration with Eskom’s unreliable power supply escalates a further two notches. You reach for the Yellow Pages in search of a small, petrol-powered generator. Then, rather inconveniently, you remember Al Gore’s award-winning movie and his message of cataclysmic climate change. You redirect your thinking patterns to vague visions of electricity-generating windmills and solar panels. Coming back to Earth, you wonder what the pragmatic opportunities are for reducing your electricity consumption. Let’s take a look. By using less electricity, you will not only reduce your carbon footprint, but you can also save money, particularly as our era of cheap electricity comes to an end. Also, the less power South Africans use, the less likely we are to experience power cuts. electricity uSage breaKdoWn
In an average home the consumption range converts to between about 230 kWh and 340 kWh per person per month. One unit of electricity equals one kWh, which, in early 2008, cost approximately 45 cents a kWh (including VAT and service charges) in Cape Town. (Note that electricity costs vary by region, usage and service agreement.) This equates to between R103 and R153 in electricity consumption per person each month. Many households may consume significantly more than this per person. Lowconsumption (less than 450 kWh a month) and low-income households, depending on the region, qualify for 50 kWh (50 units) of free electricity. It is an eye-opener to realise that for every 1 000 kWh of electricity saved, you prevent about 540 kg of coal being burnt, 1 300 litres of water being used, and the release of about 970 kg of climate-changecausing CO2 and almost 9 kg of acid-rain causing sulphur dioxide.
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This category of investments is a “must-do” – not only will it reduce your carbon guilt, it will also save you lots of money. 1) Energy-efficient lighting – the quick return Traditional incandescent light bulbs are shamefully uneconomical, with about 90% of the electricity converted to heat instead of light. Compact fluorescent light bulbs (CFLs) are far more energy efficient. Yes, they are not dimmable and they take time to reach full brightness, but they save you electricity, money and you can use them with a warm feeling in your heart. While the cost of CFLs is about four times greater than that of incandescent light bulbs (R20 as opposed to R5), they consume about 20% of the electricity of an incandescent bulb and last about six times as long. This means that they will pay for themselves within a matter of months, if used regularly, and their longer life means you replace them less often. So, throw out all your incandescent bulbs now and replace them with CFLs. Some countries, such as Australia, are going so far as to ban the sale of incandescent light bulbs altogether. The real downside of CFLs is their mercury content. So keep your burnt-out CFLs until appropriate recycling processes are found and encourage your local retailers and municipality to create recycling systems. 2) Solar water-heating – the big return Solar water-heaters are an old idea that is finally gaining momentum – to harness the power of the sun to heat water using a roofmounted, heat-absorbing plate. The heated water is fed into a special solar geyser that stores and, when necessary, uses electricity to further heat the water to the desired temperature – typically when there is a succession of cloudy days or when extra hot water is required. There are two main types of solar water-heating panels on the market: a) Flat-plate collectors: With this system, a thin, black metal sheet, covered by clear glass or plastic to improve heat retention, absorbs and transfers the Sun’s energy to the water. b) Evacuated tubes: This system consists of a set of heat-absorbing glass tubes, which contain a vacuum that reduces heat loss. More evacuated tubes are now sold globally than flat-plate collectors. While marginally
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The choices we make at home largely determine the impact we have on the world. The type of house we live in, the furnishings and technical mod-cons we choose, the food we cook, the gardens we keep – they are all a reflection of how we choose to impact on the environment and each other.
more efficient, evacuated tubes in hot areas can overheat the water, thus activating the pressure-release valve from time to time and increasing wear and tear. The glass tubes are also more fragile, which may pose a problem in areas where hail is frequent. Systems can either be direct or indirect. Indirect systems are important in areas where temperatures can fall below freezing, as the solar panels are filled with an antifreeze mixture, which prevents possible bursting of pipes. The absorbed heat is then transferred to the water via a so-called heat-exchanger. In a direct system, the water itself passes through the solar-collector panels and is heated by the Sun – this is appropriate for most parts of South Africa. The panels need to have a northward angle, so as to maximise heat absorption, and, ideally, the geyser should be placed higher than the panels to obviate the need for a circulation pump. Solar-powered pumps are available. The system lifespan is between 20 and 25 years, and sometimes longer. If you would like to support local industry and reduce transport-related emissions, purchase a system that is locally manufactured – currently all evacuated-tube systems are imported. Switching to solar water-heating is a financial no-brainer. Although the cost of the system is fairly high – typically between R10 000 and R25 000 for residential systems, depending on size – the payback period is generally between four and 10 years. There is usually not a significant difference in price between the flat-plate and evacuated-tube systems. The payback can be further reduced with subsidies – of which we are likely to see an increasing number in a bid to reduce national electricity usage. In low-cost housing projects, low-pressure water-heating systems can be installed for as little as about R5 000. While solar water-heaters can save as much as 30% to 40% of a residential energy bill, variability
in water consumption and the availability of sunlight makes calculating an accurate payback period confounding. A Namibian residential study demonstrated that, depending on usage patterns, a break-even point was reached in about five years. Of course, the higher the water consumption, the shorter the payback period. In 2005, a South African study indicated that a 2 m x 2 m solar water panel can recover R700 a year (R1 225 for a 4 m x 4 m panel), assuming an electricity cost of 35 cents a kWh. Of course, this recovery will improve as electricity costs increase. there are a number of other cost- and electricity-saving ideas to implement, irrespective of whether or not you opt to go the solar-heating route:
• Wrap your geyser and the inlet and outlet pipes in a geyser blanket and insulation material. Some high-end geysers may not require wrapping – check this with your geyser supplier or plumber. A geyser blanket should not cost more than about R200 and should pay for itself within a few months. • Turn down the thermostat on your geyser to about 55 °C. This will cost you a short, if daring and dirty, climb into your ceiling and will save you many rands a month. Remember to switch off the electricity at the mains before you fiddle with the thermostat. • Install a timer switch that activates your geyser for only a few hours each day. This means the element is not switched on every time you wash your hands with warm water. A timer switch, including the installation fee, should cost you no more than R1 000. • Also install a water-saving showerhead, which fragments the water into smaller droplets and can, depending on the manu-