HomeKit Contact Sensors: Elgato vs Fibaro
Next to motion sensors, contact sensors are arguably the most useful triggers for automation events around the home. The not only provide that triggering function, but also useful home status information regarding any open doors an gates that you may want to keep a particular eye on (eg, back door, pool gate, garage, child barriers, etc). Interestingly there are only two such sensors available for HomeKit at present, both using Bluetooth LE to communicate. The Fibaro Door/Window, and the Elgato Eve Door & Window.
The two players both have some cred, with Fibaro being a veteran in the home automation market with a focus on Z-Wave devices, and Elgato being an early adopter of HomeKit and pioneer in the area of HomeKit compatible Bluetooth hardware. Fibaro has come to the HomeKit party with 3 of their products, which now have Bluetooth variants.
So, which to choose? Interestingly these are not entirely apples to apples products.
Fibaro has a tendency to add temperature sensors into everything, and their Door/Window product is no exception. It also includes a handy tamper switch, which signals if the device has been disturbed from it's mounting location, and comes in 7 colors. Their sensor design is longer and slimmer, placing the battery at one end of the main unit and the circuitry at the other. This allows for a lower profile, but does require that the two surfaces to be monitored are reasonably level with one another. An advantage of this design is that the battery is accessible from the front by snapping off the cover of the unit, a fairly easy proposition as it's not too tightly clipped in place. Finally, Fibaro's sensor is powered by a CR14250 'half AA' battery, which is included along with adhesive backing tape.
Elgato Eve Door & WindOW
Alternatively, Elgato includes data logging functions in it's Eve app, which provides a comprehensive timeline of open/close events and statistics. That's nice for data nuts, but most people probably wouldn't look at it. The sensor itself is a single function sensor. It just determines open and closed statues and nothing more. A simple embedded LED indicates a change in status, as with the Fibaro model, and like the Fibraro unit, it's powered by an included CR14250 battery and has adhesive backing provided. Elgato's design is quite different, though, in that they opted to place the battery underneath the circuitry. This makes for a more compact footprint, but it's significantly thicker (protrudes from the attached surface more). It also means the sensor itself is raised significantly above that surface and requires the companion magnet to be raised to match. This is advantageous where you have two different surface levels to monitor. Perhaps a door with a thicker architrave or frame on a window. Elgato provides a number of 'tiles' that can be snapped together to raise the magnet up to the right level, so it's not impractical, but it does stick out a fair way if the two surfaces are largely level. So, not as visiually slick as the Fibaro model in that respect.
At this point, it looks like Fibaro might be a clear winner, but what really mattered to me was how they performed in use. Looks and extras don't count for much if the primary function is lacklustre, after all. To test the response time and range, I placed both units side-by-side on the same sliding door (location A on the map below), and placed my phone next to the AppleTV being used as a home hub, both to monitor the status updates in the Home App, and ensure I was measuring communication to a known position. The door in question was around several walls, and some distance away, so made for a good test case for the Bluetooth radios.
I had planned to associate an automation to a nearby light to each sensor in turn to test response time and reliability. This proved to be unnecessary, however, as I quickly determined that the Fibaro unit was uncontactable from that position. All attempts to trigger a status change, and update the status in the Home app resulted in "No Response". Meanwhile, the Elgato unit was trucking along and responding consistently. This was a genuine surprise. I expected Fibaro's experience in this market to get them over the top, but it seems Elgato's hard work in getting HomeKit support to work over Bluetooth has paid off with an impressive range from such a small device.
To confirm all was well with the Fibaro unit, I moved it to a different door (location B) closer to the Home Hub. From that position it began working perfectly fine, so it was definitely a range limitation. Response time from both was in the expected 2 second range for Bluetooth HomeKit devices under iOS10 (iOS11 has been reported to include enhancements to bring this down to sub-second response times). An additional small gripe I had with the Fibaro Door/Window was the adhesive backing that comes with it. The Elgato unit has a fairly thick double sided tape. The backing was easy to peel back and stuck on firmly without issue. The Fibraro backing is much thinner, and the backing tape didn't come away easily. I ended up having to use tweezers to peel it off without ripping the whole backing tape off with it. It also doesn't seem to hold as well. I had the main unit pop off the door once so far, although o be fair I noticed later that the door frame at that point had a slight convex curve to it, so it was putting some push pressure on the ends of the unit...that's also messing with the tamper switch, as the unit has to be completely flush with the surface to press it in properly.
The performance results were unexpected, but not actually surprising in hindsight. The selection is made easy if your intended install location is potentially obstructed from the Home Hub. I expect walls rather than direct range is the issue here, so any potential obstruction or interference is going to favor the Elgato product. The Elgato pricing is also much more favorable, it seems that Fibaro temperature sensor has quite a price premium. For my money, I'd opt for the Elgato unit in future simply because of the greater flexibility of placement. On the other hand, if you need something that's not white, and like to have the bonus temperature sensor then the Fibaro is worth a look.