Re: HA Holy Grail #1: Occupancy Detection

["David Gumbrell" <david.gumbrell@xxxxxxxxx>]

Hi Andy,

Apologies for bottom quoting but this s*dding gmail client won't let me
insert edit for some reason.

I managed to trial the positions of some modules by fitting surface boxes
temporarily to the ceiling. The weight isn't much so it's only a couple of
screw holes and a small Cat5 hole to Polyfilla/Paint -- but I was planning
on redecorating anyway.

Beam breaks would be superior to door switches, especially if you tend to
leave doors open a lot, which we do, but the Idratek system seems to do a
pretty good job even in that case. The door switches are probably more
significant if you have larger rooms and not enough PIRs so you don't get
enough re-triggering (in which case fit more PIRs).

I've toyed with pressure mats, but not sure about the long term reliability
and lifting floor coverings for servicing would create negative WAF.

Detecting shower "on" is the tricky part. At the moment I get
reasonable
off-to-on transition detection using an humidity sensor, but the on-to-off
is not so good (shallower curve). I considered a flow sensor, but seems
like
overkill and may reduce the waterflow (and I can't face the plumbing), so
probably will just alter the room timeout when shower off-on detected to
allow for average shower duration and then reset to shorter when redetect
on
exit from shower cubicle. Or just have a 10 minute time-out :-)

I was planning temperature sensors on the CH pipes anyway, so will probably
add one to the shower hot feed too to sharpen the Off-to-on detection a bit
further.

Cheers,

David

On 8/24/06, Andy Laurence <andy@xxxxxxx> wrote:
>
>   From: David Gumbrell [mailto:david.gumbrell@xxxxxxx<david.gumbrell%40gmail.com>]
>
>
> > The Idratek modules I have appear to use the Panasonic Napion
sensors. I
>
> > think you can get them as components from RS. They are pretty
sensitive,
> but
> > siting is still important - the datasheet has all the range info.
I
> mount
> > them over the sofa to maximise chances of retriggering. Seems to
work
> pretty
> > well. Also have to try to avoid them getting a look through door
> openings so
> > you don't get triggers walking past an open door down a corridor,
for
> > instance.
>
> Interesting. Perhaps I should run some more CAT5 to better places in
each
> ceiling. The floorboards are still up, and nothing has been decorated
yet.
> Handy!
>









> Oh - and I have door switches on all doors which helps the Idratek
> software
> > maintain occupancy knowledge.
>
> Useful. I'm thinking beam breaks about 2 feet from the ground would be
> ideal, as they detect when someone passes. I think with carefully
placed
> PIRs, pressure sensors, and beam breaks, I could get reasonably good
> occupancy detection.
>
>
> > The only room I have a problem with is because I haven't put the
PIR in
> it's
> > final resting place, so you can sit still enough for the
occupancy to
> > timeout. Don't forget that PIR's can't detect through glass (eg
shower
> > surrounds), but I'm not sure that's the best candidate for CCTV
motion
> > detection instead :-)
>
> If (shower = on) then (bathroom = occupied)
>
> Either that, or a pressure mat under the shower tray.
>
> Cheers,
> Andy
>


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