Ariel have been running a campaign to encourage us to run our washing machines at 30°C. We switched to this as our default about 6 months ago and frankly (even though we don't use Ariel special low-temperature powder) we have noticed absolutely no difference in the results. Much to my husband's disappointment, this may be the only way in I resemble Helena Christensen.
So how much difference does this make? Ariel says 40% of your energy usage (presumably that part relating to washing clothes).
When you wash clothes, 90% of the energy is used in heating the water (according to the Centre for Alternative Technology) . As energy used to heat water is proportional to the temperature rise (energy required = mass x specific heat capacity x temperature difference), this means that Ariel are assuming that 50% of the energy is being used to heat the water from ambient to 30 deg C, and the saved 40% is the additional energy required to get the water from 30 to 40 deg C. So the ambient water temperature would be 17.5°, which sounds pretty high (I would have guessed 10-12 °), but I've just gone to check it with my oven thermometer and it is correct. The 30° cycle is shorter than the 40° cycle, so this will save even more.
But how much of my electricity bill is going on my washing machine in the first place? General estimates are around 20% (I'll try and work out a better one). So saving 40% of 20% means saving 8% of my electricity bill, or 266 kgs of CO2. Just over 1% of my personal carbon footprint. Well, it's a start, and a pretty painless step.
A few more washing machine tips...
- Always wash a full load - each load uses (and heats) the same amount of water so you might as well fill it up.
- Only use the pre-wash cycle if you really need it (uses about 15% more energy).
- Use stain treaters to avoid needing to wash at higher temperatures.
- Buy an energy efficient waching machine.
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