My Dad boils up water & slurps a lot of tea, but he actually saves energy by filling the kettle to the "maximum fill" line & then pours the left over boiling water into 2 flasks so they are completely full & can be used later, to make more tea, cook noodles, or top the kettle back up & bring it to the boil really quickly because the water is already pretty hot, even the next day!
(our full kettle cost roughly 2.79 pence to boil) in just a couple of minutes.
In our house we spend over £80 just boiling water in a kettle, each year ..dad says the same sort of water heater is used in our incredibly well insulated hot water tank, & that turns itself on in a normal household for around 2 whole hours per day! ...that is a lot of energy & a lot of money!
If you follow the link above try out filling your kettle (when it is needed) & measure roughly how much it costs to boil, & then why we should only boil what we want to use & not waste the water , nor the energy used to heat it.
SO next time you get yelled at to save electricity have a look at how you can change your ways by understanding a bit more about it, our hot water is put in special "vacuum flask" which are often called "thermos" ..which is actually a brand name, but they do the same job!
This is part of the reason we have managed to save around 25% of our electricity used in the past year, Dad lined out our hot water tank cupboard with lots of insulation foam offcuts to make a super insulated jumper for the tank & the cupboard, as well as stop draughtswhich made that particular bedroom colder (the insulation deflects the cold).
The insulation (called PIR foil foam) was leftovers from other jobs, as well as some from builders who were throwing some in the skip within the village, so we estimate (think) it cost us about £5.00 & we have saved around £100.00 in a year because the water is wrapped up it stays warmer for much longer without the need to use extra electricity, essentially the airing cupboard insulation completely fills the section around the hot water tank, & the walls around it have the foil & foam insulation on the inner walls, the winter temperature in the airing cupboard rose by around 7 degrees as a result. ...that is a lot of extra energy & money saved which we can fit & forget.