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What's a Watt?
A Watt is the rate of energy use, or power. A kilowatt is 1000 Watts.
What's a kilowatt-hour?
A kilowatt hour (kWh) is the unit of energy that is used to measure electricity consumption. It's the
amount of kilowatts used over a one hour period. For example, a common light bulb uses 60 Watts.
If it runs for 24 hours a day, for 365 days a year, it will run a total of 8,760 hours. This means the light
will use 525,600 Watt hours of electricity in the
year. To convert Watt hours to kilowatt hours, divide by 1000. Therefore an ordinary light bulb running all year
will use around 526 kilowatt hours of electricity per year.
What's a joule?
A joule is the standard unit of energy. Gas consumption is measured in Gigajoules (GJ) which represents 1,000,000,000
Joules. 1 kilowatt hour = 3.6 Megajoules.
What's energy efficiency?
Energy efficiency is about getting the most production from every unit of energy put in or producing a product using
the least amount energy as possible, without compromising quality.
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How is energy related to greenhouse gases?
The main greenhouse gases produced by human activities are carbon dioxide, methane and nitrous oxide. Each of
these gases traps a different amount of heat. A kilogram of methane traps as much heat as 21 kilograms of carbon
dioxide, while a kilogram of nitrous oxide traps as much heat as 310 kilograms of carbon dioxide.
Throughout this
Manual, the effects of the different greenhouse gases are expressed in terms of carbon dioxide.
Whilst carbon dioxide cannot be smelt or seen, it can be weighed. A kilogram of carbon dioxide would fill a large
family fridge and a tonne of carbon dioxide would fill a family home.
Most of these greenhouse gases are generated from the use of energy. The amount of greenhouse gas emitted depends
on the type and amount of fuel used to produce energy. For example, in NSW, 1 kilowatt hour (kWh) of electricity produces 1.08 kilograms of greenhouse gas whereas the same amount of energy from natural gas produces only 0.0594 kilograms of greenhouse gas. Therefore, energy from coal (electricity) is more " greenhouse gas intensive" than natural gas. The 60 Watt light bulb from above, which runs all year and uses 526 kilowatt hours of electricity, generates 568 kilograms of greenhouse gas. 1000 kilowatt hours = 1 Megawatt hour = 1.08 tonnes carbon dioxide
per year.
Converting energy savings to cars off the road
You will find throughout the Manual that energy savings are converted to a number of cars being taken off the road.
It has been calculated that a car travelling on average 15,000 km per year will produce on average 4.5 tonnes of
carbon dioxide per year.
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