SUSTAINABLE HOME DESIGN
Making South African Homes More Environmentally Sustainable

Electricity

Calculating Costs | Solar panels | Transformers | Wind Turbines | Pool Pumps | Rechargeable Batteries| Electricity Further Reading

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Calculating Costs

On average, up to 50% can be spent on heating your geyser, up to 60% on heating and cooling rooms and between 15 and 30% on lights, appliances, cooking etc (yes this doesn't add up to 100% - it just shows the extremes of usage). You loose about 30-40% heat due to poor sealing. Windows and doors loose about 20%, walls 15-20%, roofs about 10% (some numbers from The Natural House Book). Saving electricity is about two things – saving money, and the resources used to generate electricity from the supplier.

Electricity in South Africa on average currently cost 30.5 cents per kWh (1000 Watts used per hour) on prepaid systems ex. VAT and 34.77 cents per kWh inc VAT. To see how much it costs per region in South Africa download the PDF from http://www.eskom.co.za/live/content.php?Category_ID=26

So to use a 72cm TV for an hour that uses 148W at 34.77c/kWh will cost:
148W/1000W
=0.148
X 34.77
=5.15c

Now compare a geyer that uses 3000W:
3000W/1000W
=3
X 34.77
=R1.04

Now multiply that by 24 hours and 30 days, give or take time off due to the thermostat…

Some appliances don't state their wattage – for example cell phone adapters. They might state something like:
Input 220V 0.2A
Output 5V 1A

Watts= Volts X Amps, it's easy to see that the above consumes:
220X.02
=44W

So 44W/1000W
=0.044
X34.77
=1.53 cents per hour

The problem with adapters is that you probably have lots plugged in all over the place –as does the rest of the planet, often plugged into something not being used…

Solar panels

Solar panels can be used to power a slice of household electrical appliances. Solar panel technology is still low in efficiency, even with newer technologies that have been in the press recently (read about the two competing technologies here http://news.com.com/Silicon+vs.+CIGS+With+solar+energy%2C+the+issue+is+material/2100-1008_3-6121488.html?tag=nefd.lede ). You also have to install inverters, batteries etc for a solar system.

Suppliers:

Transformers

Transformers draw electricity even if the receiving side is not plugged in – so switch the wall socket off to them when they are not in use. The same is true for most AC to DC converters (cell phone chargers etc).

Wind Turbines

There are several wind turbines available suitable for home use. Of course you need to live somewhere in South Africa where it blows a lot, like Port Elizabeth or Cape Town. Two general types are those that generate electricity and store in a battery, which goes through an inverter into the house electricity supply, and those that simply plug into a wall socket and supply electricity to the house when the wind is blowing.

In addition to installing your own wind turbine, you will soon (in theory) be able to purchase wind generated electricity in South Africa
http://www.capetown.gov.za/en/Pages/Results.aspx?k=wind

Pool Pumps

A different angle on the environmental side – noise. Noise pollution creates stress. Pools should alleviate stress. So get a silent pool pump (and put it in a sound insulated enclosure). Check if your local pump supplier sells silent pumps – one brand in South Africa is ESPA (look up ESPA pool pumps on the web and you'll find many local suppliers). You could also enclose the pump in a brick or underground enclosure to keep noise levels down.

In the marine industry boat motors are enclosed with noise insulation materials - have a look at http://www.halyard.eu.com/NoiseVibrationReduction/NoiseInsulation Materials.aspx from the UK.

Rechargeable Batteries

According to a study paid by a rechargeable battery company (although the company who undertook the study is well respected), rechargeables are far better for the planet: http://www.rechargeonslaplanete.com

Electricity Further Reading

A new type of solar system in the making:

Links to more reading and potential devices: