I haven't tried it, but would have thought that you would get lots of
false alarms due to sunlight & temperature changes. PIR's always say
"don't point at a window", well you can't really avoid that in a
You can get "dual technology" detectors which combine doppler radar &
PIR, that might work.
Our shops used to suffer false detection due to large plate glass windows
and thermal effects, but we never pointed PIRs at the plate glass they were
usually mounted above.
In your case a 'break glass detector' coupled to door contacts may be the
way to go.
I don't mean the silver tape you see applied to large commercial windows;
the BGD is more of an audio device. The combination of an impact & the
breakage will trigger it, a single sensor will cover a 16m2 area easily.
Sadly alarms didn't seem to bother the ram raiders we were prone to.
You would have to fit a dual-tech microwave passive infra-red if it's in a
situation like that. A dual-tech must have a moving heat source to be
activated properly and is designed for such an environment such as
conservatories and areas where wide temperature and lighting variation
occur. There are many different styles and sizes on the market now, so you
can pick one that will suit your surroundings.
Here's an example of just one from Pyronix:
A web search for dual-tech PIR will bring up many more.
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