Energy Efficiency

Let’s minimise that consumption!

There are a number of things that can be done to reduce the home or building’s inherent electricity consumption…

Firstly, what is a kiloWatt (kW) and what is a kiloWatt hour (kWh)?

A Watt is an electrical measure for power; a Watt hour, on the other hand, is the amount of energy used in an hour. So one refers to 'power' the other to 'energy'.

For example, a simple light bulb may be rated at 50 Watts; this means that if it is turned on, it will use 50 Watts of power. If it is used for one hour, then 50 Watt hours will have been consumed.

If it is used continuously for 20 hours (of course this is not realistic, but for the sake of the exercise) then that is 50 Watts x 20 hrs = 1,000 Watt hours. Since 1,000 Watts is a KiloWatt, (Just like 1,000 grams is a Kilogram) then 1,000 Watt hours is 1 KiloWatt hr ( or "kWhr" to use an abbreviated form).

It is important to understand what the kWhr is because this is the basis used by retailers to calculate energy costs. For instance, if your retailer is charging you 20c / kWhr, then that means, taking this example, where the 50 Watt bulb was left on for 20 hrs and used 1kWhr, the charge would 20c.

What are typcial Australian homes using?

The average home in Australia consumes about 18 kWhrs/day. There are a number of energy-efficient homes that are running at under 6 kWhrs/day, while still enjoying a decent standard of living!

Now that we have an idea of the basics, let us look at some examples of where our power goes in our homes...



The big ones:

Heating :
Usually there will be a data plate on the heater (if electric) showing the number of Watts it consumes. What does it mean? Well a 1200 W heater, running at full power will consume 1200 Watt hours of energy in one hour, or 1.2 kWhrs. If your retailer is charging you 20c / kWhr, then this would cost 20c x 1.2 = 24 c. Now this may not sound like a lot of power, but do bear in mind that a 1.5kW solar system (as an example) will produce, under ideal conditions, about 1.5kW of power, and if it did that for an hour it would have produced 1.5kWhs of energy.

Often, running an electric heater at say 60% of its maximum setting can lead to a 50% reduction in its energy consumption.

Cooling : Again, have a look at the air-conditioner’s rating plate. The same maths applies as above.

Spas and Pool pumps:These are heavy loads and ideally should be avoided. However if you must have them, you could move their running to off-peak times.

Dishwashers and Washing machines: A 45 degree C wash in the washing machine will use about 500 Watt hours (0.5 kWhrs) and a 95 degree C wash will typically use double that. Similarly a short wash in the dishwasher will use about 0.5 kWhrs, while a full 1 hr 20 minute wash will use about 1.5 kWhrs !

The smaller culprits…
but they can add up:

Lighting: CFL (Compact Flouroscent Lamps) use a lot less energy than the standard incandescent lamps; however there are some concerns about Electro-Magnetic Radiation from such lamps. So, do some research before making the change.

You may also use LED lamps.




Other devices:

As much as possible, it is recommended to put appliances off from the mains. Some old laptops, for instance, can draw as much as 70 watts when left connected to the mains, even when the laptop is off. That is 700 watt hours of energy a typical night, and 225kWhs a year….

Boiling water, electric sandwich makers, etc.

These appliances use a great deal of power though for a very short duration of time. However, if overused they can end up costing a lot. For instance, why boil a litre of water when you only need a cup? Or why run a 1800 Watt sandwichmaker for 40 minutes when 10 would have been sufficient? By planning your work a little, you'll find you can get to that magic number of about 6 kWhrs/day (and that data is for a 3 - 4 person home).


Energy-monitoring units:

Often it is quite hard to establish how much power different appliances in a home use and certainly hard to know your running total of energy consumed for the day.

One simple way of getting a handle on this is to install an energy-monitoring device like the Efergy Elite. This way you can establish exactly how much power you are consuming at any given point in time as well as make comparisons with previous days of energy used.


Consumption at businesses tends to be more complex. Typical loads tend to be motors, heating, cooling, etc.

Other measures to reduce electricity consumption would include installing a Solar Hot Water or a Heat-Pump unit. Heat Pumps use considerably less power, upto 28% of the normal electric power used to heat the same amount of water.


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