Due to some dubious career advice, I left school at 15 and spent a couple of years as merchant seaman followed by some time in a factory. The fact that I have spent much of my career writing computer software, suggests that I was not cut out for a life on the ocean wave. Whilst I was close to incompetent, as this experience drifts further into the past, I am attempting to mine it for anything relevant. Remuneration was not generous but included two bars of soap per week, both were brick like, one was a dark red carbolic variety which repelled both women and infestations, but as only one of which was present on the ship, this was not a problem. The other was yellow "Port Sunlight" which was used for laundry. Both types could be used as currency in some ports.
The laundry process (known as dhobying) consisted of placing soiled clothing in a bucket of water, rubbing it with a lump of soap and agitating it until one was either bored or the clothes were clean. A couple of rinses in clean water and the process was almost complete. Ships have lots of warm spaces, so getting stuff dry was not a problem. As this was hand washing, I doubt if the temperature of the water was very high. The standard of personal hygiene in a all male community frequently engaged in dirty work was reasonably high (with the odd exception), so who needs more than a bucket and a bar of yellow soap?
Fast forward some decades and home is a suburban semi populated by two adults and three would-be adults and a washing machine. The latter consumed 1.0 to 2.0 kwh/wash, maybe 3 to 8 kwh per week. Eventually, the children leave and the washing machine unable to cope with an empty nest, starts to leak, vibrate and die. It is removed by two men who swear a lot. The replacement provided by the insurance company is in my opinion dynamically unstable and can't be left unattended. I have agreed to perform a certain number of washes to see if the machine "settles down". Rather than just staring at a vibrating cube, I weigh the washing before and after and measure the energy consumption.
Initially, my wife selected a programme with a 40 deg. C temperature and I duly filled and emptied the machine and drew a graph. A typical wash requires about 0.7 kwh of electricity, which is a significant improvement on the old one. The energy consumption is proportional to dry weight, so this maybe due to the amount of energy needed to warm the contents of the drum. When I eventually got to study engineering at university, we were taught about experimental design, so when my wife was not looking, I dropped the temperature down to 20 deg. C, so far she has not noticed any difference but the energy consumption is now 0.3 kwh/wash. It's emulating me and a bucket or was I emulating the washing machine but that's philosophy not engineering and I'm not qualified. Low temperature washing will not work for greasy overalls or skid marked underpants, but not every wash contains those things.
Modern washing machines are highly energy efficient, but there is no obvious way to interact with their energy consumption. Smart meters might help, or even a stupid meter mounted in the kitchen so that a home's energy consumption is visible. The energy meter I use cost less than £20 and has paid for itself, so it would not be significant cost increase to incorporate energy monitoring into a washing machine or similar device. My opinion is that most homes could drop their energy consumption by 10 - 20% without any lowering of the standard of living, if only they knew what it is. Once we were using 5kwh/week to keep clean, now it is less than 1 kwh.
