How to Select Energy-Efficient Appliances

It’s practical (though not very convenient) to carry an energy meter with you every time you want to measure the energy consumption of a potential electrical appliance purchase.  There are many retail sources for such meters. The meter can be plugged into a wall outlet, with the appliance connected through the meter for a reading. The figure displayed shows the electrical power consumed by the connected appliance, measured in watts (W).

Many of your home’s main electrical appliances, like washing machines, food processors, refrigerators and dishwashers, use a standard 120V outlet. The electric flow in amps (A) times the pressure in volts (V) gives the wattage. 

A common food processor running on 2.4A will use 

120V x 2.4A = 288W

An electric kettle on 12.5A will use

120V x 12.5A = 1,500W

What does this mean for you as a consumer? In practical terms, it means you need to compare not only the initial outlay for the item but its ongoing power cost over time.

For example, while shopping for a new television set you may find two units that meet your requirements for size, aesthetic appearance and so on. You bring out your power meter to measure the energy consumption or (more conservatively) you check their labels for electrical ratings. Imagine that model "A" uses 162W and model "B" needs 1.9A.

This might remind you of those grade nine science problems that always start “A car moving west...", but this one’s easier. You know that power is calculated as voltage times current, so for model “B”:

120V x 1.9A = 228W

Assuming both models cost a similar amount, it becomes obvious that model “A” is a better buy because it offers huge savings over time and reduces the need for additional off-grid renewable energy equipment (and also reduces greenhouse gas emissions as well). You may even impress the salesperson with your knowledge!

However, power is only one part of the calculation – you also need to take usage into consideration if you’re off-grid. Someone who watches television for two hours a day will be better off with model "A", whereas a home that watches for 1 ¼ hours a day could choose model “B”:

• Model "A" energy consumption = 162W x 2 hours = 324 watt-hours
• Model "B" energy consumption = 228W x 1.25 hours = 255 watt-hours

In either case, it is advisable to switch off equipment if a room is empty. In an average home, t he day’s lowest power consumption is from midnight, when most electrical appliances are turned off or in “standby” mode. This is your home’s "base load".

One would think the base load should be zero with all appliances ”off”, but many still consume energy. Any electrical appliance with an instant-on feature, such as microwave ovens, cell-phone chargers and doorbells, consumes energy all the time, even when not in use. This is “phantom energy” or “phantom load”: a continuous waste of energy with no real benefit.

Similarly, an electric water heater uses a lot of power when it is in