1. Take a reading of your electricity meter and write it down along with the time.
2. The next day, at the same time, take another reading.
3. Enter the numbers in these boxes:
• On the first day the reading was: kWh
• On the second day the reading was: kWh
4. Press the button to your energy usage.

You used in one day.

A diesel generator can produce around 3.2 kWh for each litre of fuel it uses up. To produce the energy your household used in one day would take of diesel fuel.

One square metre of solar panels can produce around 0.66 kWh in one day. To generate the energy your household used in one day would take of solar panels.

I found I used 19 kWh in one day. This worked out to 6 L of diesel fuel and 29 square metres of solar panels. This would mean using 2,190 L of diesel a year. You may find your usage is higher than this, because some of the energy used in my home comes from natural gas instead of electricity.

I should mention that the figures I used for how much fuel a generator uses or how much power a solar panel generates are only approximations. Diesel generators and solar panels vary from one manufacturer to the next, but this will give you a rough idea of how much you would need to use. If you would like to see how I arrived at these figures, you can take a look at http://www.csiro.au/helix/sciencemail/activities/EnergyUseSupplement.html

In August, you will be able to try a similar activity as part of National Kilowatt Count. During the Kilowatt Count, people all over Australia will be measuring their household energy use. As well as electricity, the Killowatt Count will measure how energy people use from petrol, natural gas and other sources. If you would like to know more, check out http://www.kilowattcount.gov.au

It will be the national project for Science Week (17-25 August 2002). National Kilowatt Count is supported by the Australian Greenhouse Office, CSIRO, the Commonwealth Department of Education, Science and Training; EnergyAustralia, Alcoa World Alumina Australia and TransGrid.

Supplement
Tips for reading the meter

Most electricity meters have dials that look like this:

The dials will often be labelled to show which is the ones, tens, hundreds and so on. If not, just assume the dial on the right is the ones. Be careful taking the reading, as normally the numbers on the dials will not all go the same direction. If the needle is part-way between two numbers, use the lowest one.

For the dials in the picture the reading is:
· 3 from the 10000 dial (rounded down)
· 4 from the 1000 dial
· 2 from the 100 dial
· 2 from the 10 dial
· 6 from the 1 dial (rounded down)
So the reading is 34226 kWh

Some meters have a dial for 0.1 or 1/10 kWh, but it measures such a small amount that it's safe to ignore it.

Figures used in "What do you use"

The figures for diesel consumption and solar energy used in the "What do you use" are approximate and based on information in magazines or on the internet. The figures were worked out as follows:

Diesel

The exact consumption of diesel generators depends on the manufacturer, the model and the load placed on it.

The figure of 3.2 kWh/L for diesel generators was determined by performing a web search for diesel generators, then comparing their output with fuel consumption to work out how many watts they produced per litre of fuel used. For example, a generator that produced 28 Kilowatts and used 9 litres of fuel per hour would produce (28/9) kWh/L = 3.11 kWh/L. 15 models from 3 different manufacturers were averaged to produce 3.2 kWh/L.

Solar panels

Exact output of a solar panel array would vary depending on manufacturer, size, number of hours of sun per day and the angle between the sun and the panel.

An average was taken from a comparison of solar panels given in Soft Technology magazine issue 43. An average was taken of thirteen different models from three manufacturers, giving 110 Watts per square metre. Assuming six hours of useful solar energy per day gives 0.66 kWh per square metre per day.