Hot / warm water into the washing machine

Thanks to Simon, I ended up at a great evening at the Eden Project on Wednesday. It was run by the Cornwall Sustainable Building Trust. Some great speakers including Charlie Luxton who covered a lot of items I already knew about (it’s always great to get confirmation from somebody with heaps more experience than yourself thought !), and quite a few I didn’t.

Warm Water into your Washing Machine

For instance, modern washing machines have a single water inlet, for cold water. But what this means is that these modern washing machines are using electricity to heat the water to the desired temp for the selected wash. Eeeeek, we all know that due to (not only) transmission from power stations for most people, the efficiency of heating water by electricity is shocking (see figures below *).

How about making sure that there are mixer taps to give warm water eg 20 degrees into the back of your washing machine.

Water Temperatures

  • Central heating tends to run at 55 to 65 degrees C.
  • Under floor heating runs at around 45 degrees C.
  • A bath is going to be, 44 to 46 (a VERY hot bath) degrees C.
  • BUT need to occasionally boost the water in the tank to kill legionella:
    – 66°C Legionella die within 2 minutes
    – 60°C Legionella die within 32 minutes
    – 55°C Legionella die within 5 to 6 hours


He also mentioned that instead of cement (environmentally horrible stuff) go for GGBS  +/or fly ash cement. It seems these are cements made up from the by products of already in place (and here to stay for a while) industries such as blast furnaces and coal burning.


* Energy and Electricity

These figures are taken from an eco building book, the Green Building Bible (Volume 1):

  • 100 units of energy in fossil fuel into a typical UK power station, gives
  • 38.5 units of energy into the grid, of which a further 3.5 units are lost on transmission & distribution, so you only get
  • 35 units to a house, of which 13 lost through inefficient use

So 100 becomes 22 (or 35 if you have 100% efficient use, through good appliances, voltage regulation etc.)