New, need exterior light sensor?

Hello all, Moved into my forever house in the last year and just starting on hubitat. Lots of things I want to accomplish; gonna start with exterior lighting. Currently there are 13 fixtures controlled by 9 switches in 6 rooms. I think I understand how to set this up with smart switches and day/night mode... but I'd also like the lights on overcast/stormy days.

So I need a exterior light sensor! Any recommendations? I want to be able to control the trigger light level. If it was part of a motion sensor that be useful too.


Hue outdoor motion sensors also report lux levels. Pricey compared to other motion sensors, but they work pretty well.

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I've used Fibaro Motion Sensors but installed them in a weatherproof enclosure. I've soldered wires to the battery terminals and hooked them up to 5V supply so I don't need to bother with batteries.

A couple of things to bear in mind:

You'll want more than one sensor. Unless all of your windows are on one elevation, there will be (sometimes immense) differences between the light level on different aspects of the house. Currently my front sensor measures 980lux while the rear is 380lux (it's 8:45 AM here). I've known there to be differences in the thousands. Alhough the differential between levels gets less toward sunset it can still make a difference.

If you're going to use them for motion as well, the likelihood is that you'll mount them fairly low down (8' maybe). You must make sure that they are not affected by any external lighting you install for two reasons. The first if they're controlling the external lights, you can end up in a loop situation - it's dark, the lights switch on, which makes it light, the lights go off. I have that issue for around a half hour at sunset where the sensor is mounted above some ambient lighting (I intend to physically mask the underside of the exposed sensor to fix that). Secondly, if the sensor will be used just for internal light automation, when your external lights come on, they could keep the light level higher meaning your internal lights aren't coming on at the desired level.

For those reasons I have my sensors high up, where they are in direct light but not affected by any other lights. I use them solely for illuminance and temperature.

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I like the Hue outdoor sensors as well, I have 4 of them. The Hue are ZigBee and use AA batteries. I just picked up a Zooz Zen ZSE29 V2 and have let to deploy it. It also reports lux as well and uses AA batteries but comes with an adapter to use a phone charger/wallwart if desired. It probably is more versatile for mounting than the Hue, and is bigger than I expected. Oh, it's also Z-Wave Plus.


Hue (Zigbee) and Sensative Strips (Z-Wave) are both designed to be weatherproof. Hue uses AA batteries, Sensative has a non-replaceable battery rated for 10 years (note: none of my Sensative window/door sensors lasted more than 6 years). Both are $$$.

Not sure that I understand. The Hue sensor comes with fittings for flat wall mounting, inside corner, outside corner, or strap mounting (I have 3 zip-tied to gutters).

The Hue is IP54, whereas the Zooz suggests protection from sun/rain. That would be a deal breaker for my current applications. Color preference is subjective. We have lots of brown tones on our house, but I could see someone with white trim preferring the look of Zooz.

@johnwill1 brings up some good points. A sensor provides data points, but you have to consider how that can be actionable information. When we moved, I had to re-tune my scheme for a different house layout and more cloudy weather.

If using motion sensors, then note the manufacturer suggestions for mounting height. If memory serves, Zooz is 6' and Hue is 7'. This will yield the best range and sensitivity for motion. Like most multi-function tools, you can never optimize more than one function. I optimize for motion and then combine lux readings to get a general idea of outdoor illumination (front, back, and overall).

I never found external lighting to be a factor with lux readings. My worst case scenario is a 2100 lumen floodlight 10' (3m) above one sensor. It impacts the lux reading by perhaps 5 - several orders of magnitude lower than what I would consider "bright". I can imagine that having the sensor directly above or beside the light source would yield different results. In those cases, I would consider adding some hysteresis - dark if drops below 1000 lux; bright if above 1200 lux for 10 minutes, for instance.

If you read this far, then welcome to the community! Looking forward to hearing about your projects and journey!


Yeah I have mine report each minute and have them available to view on a dashboard. For some under cabinet lighting in the Kitchen, rather than guess I kept an eye on the level and decided when the light was needed. I then set up a Hub Variable to switch at that observed value and built my rule around that.

That's what's happening in my example. I've a sensor at about 10' above my deck. I put it in a specific corner to never be in direct sunlight as the temperature readings were wildly inaccurate. It is used to turn on the ambient lighting in the garden and the rule is set at flip a boolean that will turn on/off the lights at 15 lux. When it reports 14 the lights come on, one of which is a GU10 3.5W walkover uplighter in the deck. It then reports 20 or so causing it go off. It all settles after a time as the sun sets but I need to tweak it with a delay to resolve it.

If you have existing floodlights then this too is a possibility.. I am using them in our backyard/garage..

I actually have them added to our older model Ring floodlights..

edit: Their lux detection is kinda wonky but workable so if super accuracy is important then these might not be the devices. They work fine for my purposes though, and motion sensing is decent.

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Ha! One of my favorite examples of multi-function sensors that can really only do one thing well. This is a good reminder to remove all but our North-facing sensor from my dashboard. On a sunny winter afternoon, our front porch will report 80F while the backyard reports 30F.

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Agreed. Get three sensors for each elevation :laughing:

No.1 is motion only, positioned at 8' to detect movement across the coverage pattern
No.2 is illuminance only, positioned well above all light sources in direct light
No.3 is temperature only - tucked away in the shade somewhere

With some careful thought/positioning they can satisfy more than one capability.

I have some other sensors for external detection that are currently not linked into Hubitat. My front multi sensor does illuminance only as it gets full sun and reads ridiculously high at times. My rear sensor does illuminance and temperature. Once I've bodged a shield to the underside of it, it'll do those two jobs nicely.

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I went through this journey, and for a long time was using this OpenWeatherMap driver to control interior lighting. It will produce an approximate lux value based on time of day and weather conditions. Not perfect, but it's something you can get started with ASAP.

I started looking at exterior illuminance sensors, and eventually realized I had the perfect solution already present -- solar panels. So my interior lighting levels are now driven by the current production levels of my panels. The primary flaw is that after a big snowstorm, the house stays in Dark mode until the snow melts off the panels; I can live with that, as we get that much snow relatively infrequently.

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My lighting rule requires only a single report under the threshold to move down a level, but ten continuous minutes above the threshold to move up. Something like that might be workable, depending how long it takes to settle.

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Hi there @Hatallica, your points about Hue mounting options are all valid. I'm also using mine in the same manner. The only reason I purchased the Zooz is due to having only a horizontal mounting location. The Zooz tilts to allow this, but it does not pan/swivel (would be great if it did). If I had other mounting points I probably would have just picked up another Hue do to familiarity. I did see a silicone gasket around the battery compartment, there must be other areas of moisture ingress. -Joel

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Yeah I've done something like in my rule but I've somehow cocked it up and the wait isn't working correctly. It's probably my incorrect use of Private Boolean. It'll be my user error I'm sure

Thanks all, lots of helpful stuff here. I ordered up the hue outdoor sensor and will stuff it under the north side eaves since there aren't a lot of lights around there.

Also ordered a pair of g2 floodlight sensors for motion detection purposes. I'll swap these into existing fixtures where the original sensors are old/iffy.


Now I understand! Thanks. I forgot that the Zooz allows for some physical adjustment.

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