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Energy use findings

I have found it quite useful though to think in comparative terms. With a colleague at work we hit on the idea of converting energy use into mugs of tea equivalent - i.e. the amount of electricity required to boil enough water to make a mug of tea. You can try this yourself if you have an energy meter or work it out with a bit of GCSE Physics...remembering that the specific heat capacity of water is about 4.2 J/g/ºC ... :o)

Our kettle took 115 seconds to boil 2 mugs worth (as there was a minimum fill line in the kettle) of water from the cold tap. It is a 1.9 kW kettle so the amount of energy required was:

1.9kW × 115sec ÷ 2mugs ÷ 3600sec/hr = 0.03 kWh

Or to convert energy figures in kWh to mugs of tea, you need to multiply by (1 ÷ 0.03) = 33. For example, spending a hour watching a 160 Watt flat screen television = 0.16 KWh or about 5 mugs of tea.

Some examples that I found:

• I have longer than average hair so I take more than the apparent average amount of time in the shower, call it 10 rather than 5 minutes. In an electric shower that is equivalent to 50 mugs of tea...or nearly 1 ½ miles driven in an average car...or 6 solid months of a old mobile phone charger.
• I have an 8-year-old, LED clock radio, which I really like. I was worried that it might be an "energy vampire", as it is warm to the touch, however it uses about 2 Watts, which is equivalent to 1 ½ mugs of tea per day (or 12 seconds in the shower).
• In hunting down the "standby beast" - note that a lot of literature on energy saving tips suggest that we waste approx 8% of our energy through leaving appliances in their standby mode (rather than switching off at the wall), e.g. from The Big Green Switch - I found a few nasty "vampires" (like TV's). However, there were a lot of things registering about 1 Watt (e.g. clocks on microwaves): that is about ¾ of a mug of tea per day per appliance. It is worth knowing which ones are worse so you can make sure they are switched off when not in use.