"Mike Clarke" wrote in message
o.uk...
On 07/03/2015 11:32, Roland Perry wrote:
In message , at
16:44:47 on Fri, 6 Mar 2015, Mike Clarke
remarked:
"... Energy meters show which appliances use the most electricity so
that you can plan energy use effectively. Because of the different
ways that appliances use electricity, such data could, for example,
reveal whether you use medical devices or baby monitors, or even show
the TV programme you're watching. And obviously, it can give
information on when you're in or out, or track when you toilet light
goes on. So, technically, it might know when you are on the loo."

So smart meters have magical telepathic powers.

These sorts of comments are based on an ability to do a waveform
analysis (of your total consumption) and pick out the components using
fairly basic digital filtering methods.

For example, if you see a 2kW spike that lasts around 90 seconds, you
can hypothesise that it's an electric kettle or a toaster. And if it
happens during Coronation Street advertising breaks, more likely the
latter (and will also correlate fairly well with watching ITV).

Yes but this would require continuous real time analysis, probably too
complex for a design that just sends power usage for each 30 minute
period.

Other appliances will have their own characteristic components.

The TV programme thing is also related to being able to filter out a
pattern where the power consumption of the TV varies with the brightness
of the picture, and seeing if any of the contemporaneously broadcast TV
channels has a likely candidate.

These variations will be very small compared to total usage by everything
else in the house. I doubt if smart meters will have that sort of
computing power. And likely to be unable to sort out what's happening if 2
TV's are in use in the house at the same time with people watching
different channels.

And as to the claim "track when you toilet light goes on" - it's going to
be a very smart meter to know the difference between the light in the
toilet and any other light in the house.

But not necessarily very smart at all with the usage pattern.

There aren't any other lights with that usage pattern.

What I'm not convinced about, however, is whether the smart meter in
your house [one of which was shown on Breakfast TV this morning] can use
those sorts of techniques to tell you how much power your deep freeze is
using

That would probably depend the use of smart devices capable of talking to
the meter.

Meanwhile, one of the hiccups with the scheme is apparently that telling
people what the cost of their consumption is *now* [I have had a
clamp-on meter for that for over five years now] results in them using
*more* electricity not less.

For example mine is telling me that my current consumption [the
background on a Saturday mid-morning] is ~600W at a cost of £1.77/day.

Exactly. instantaneous values are pretty well useless for overall cost
calculation purposes.

But could for example tell you that the way you use the outside
lights could save you useful money if you changed them to LEDs
or that the way you use them means that changing to LEDs isn't
going to save you anything much.