On 21/04/2017 12:23, NY wrote:
"Andy Burns" wrote in message
...
Even if all 220 million EU households bought a new vacuum that used
400W less than their old one and used it for 2 hours a month, it would
still be 2749.8 TWh

But *would* it still be for 2 hours a month. If you simply reduce the
motor power, without making that motor power produce more suction, all
you are doing is meaning that the device has to be left on longer to do
the same amount of work, because you have to keep going over the bits
that a stronger suction would have picked up first time.

That might be why the EU regulations stipulated that they had to produce
more suck for less power and not just use less power.


It's the same with kettles. It takes a fixed amount of energy to boil a
given amount of water, so if you reduce the power, the kettle must be
left on longer to boil that water - no saving of energy and certainly no
saving of time (quite the reverse).

But less load on the generators.


Better to encourage people to heat less water - don't boil a full kettle
if your teapot only holds half a kettle-full. Or else encourage people
to use the remaining hot water as part of the washing-up water.

Ban kettles and only have hot water dispensers that heat exactly the
amount needed. Like the Tefal hot cup.