Boris Johnson and money saving kettles.

maybe buying a taller thinner electric kettle, so the minimum load is less, or indeed putting the kettle on the gas ring.

I do recall from O level mocks contention about a question involving the energy used to heat a kettle with a given layer of chalk inside providing some thermal insulation.

Pretty much half of the class solved it with heat on the outside going in, in the manner of a gas ring, and half the class assumed the heat from within like an electric kettle. The teacher -clearly the all modern miss with an electric kettle- was a bit surprised to be told  there were 2 valid solutions.

In the intervening short time (ahem three decades, Mike), I suspect most households no longer have a kettle for the gas hob.

Mike

Still made and sold though.

Okay, if you have an old kettle with an element stuck in the middle of the kettle and the element has to be completely covered with water, it may require a minimum fill of several cups of water, so a kettle like ours that  has the element lay flat in the base is more efficient when boiling one cup of water 

Haden Standard Kettle Element - Backer Electric

Any other energy saving kettle features?

Any other energy saving kettle features?

I reckon many are a bit slow at automatically switching off when they get to the boil - especially when boiling small amounts of water and steam seems to have to fill most of the remaining space before triggering the sensor. There's room for improvement there I reckon.

    - Andy.

If Boris is referring to the older all metal kettles,would they not lose more heat before

boiling compared to plastic kettles?

                                                      Hz

I have never fully understood why, but some kettles are faster than others of the same wattage. I suspect that some are more efficient than others when it comes to changing electrical energy into heat.

If some of the electrical energy isn't being turned into heat, then it must be turned into something else.  That seems unlikely in a kettle.

More likely, it's about thermal conductance between the element and the water.

or at least the fact that some of the heat is lost to the environs - a shiny metal kettle will lose less than a dull one. Worst would be matt black like a heatsink, luckily not that common....  Also note that there is a fair old variation between 'identical wattage' elements. The factory do not like rejects, so almost anything goes out the door.

Mike.

More likely, it's about thermal conductance between the element and the water.

Sounds plausible - an element covered with limescale is going to take longer to heat up the water. It's not that less heat is generated - just it's harder to get that heat into the water, so the element itself contains more of the heat (i.e. is hotter) when boiling finishes. Unless the kettle is immediately re-filled and boiled again, the extra heat in the element will be gradually lost to the surroundings.

     - Andy.

Where do the 'instant hot water' taps sit here though? Are they more or less efficient than boiling a traditional kettle? 

I take the point, but are you saying that all heating elements are as efficient as each other?