installation of temperature sensors

Nico94 · 29 November 2018, 15:39:04

Hello,

I plan to install temperature sensors and ideally humidity too in a building for residential use. From what I understand the Zwave protocol seems to be the most suitable because it allows the sensors to relay the signal. The apartments are spread over 14 floors so the signal can not be broadcast throughout the building.

The goal is to record temperatures and track their evolution because many residents complain about being too hot or too cold but nobody do something. Ideally, I want to have a temperature record per hour, updated once a day with 1 or 2 sensors in about 30 apartments. Ideally the sensor should work on battery and be aesthetically neutral for a price of about 30 € each.

Which monitoring tools and sensors do you think are best for this purpose?

Do you have any advice?

Thank you

Beta-User · 29 November 2018, 16:08:33

First: Welcome to the FHEM forum!

Quite impressing project. In general, Zwave might be a good choice, but some remarks:
- afaik battery driven devices will not act as a relay. You might need some mains powered devices to do that part of the job.
- when using too much repeater functionality across the distances you might end up with a lot of conflicting RF traffic and get unreliable results in the end; afaik, nobody did some testing in any comparable environment.
Perhaps this could be reduced in organizing the net more in segments (e.g. one GW for 2-4 floors somewhere in the middle there, GW then should have regular IP-network - could be e.g. a PI for ser2net - of course this would raise further questions and explicitely is no recommendation but just a first idea).

Using battery-driven sensors might not be a lucky choice - someone has to monitor battery life and change batteries...
If ever possible, I'd recommend wired devices (despite not having any clue where to get them).

The only harware beeing directly able to cover that kind of distances the RF way are LoRa ones, but that's self-making devices...

However: Good success!

Beta-User

MadMax-FHEM · 29 November 2018, 20:06:10

Right.

Just one thing to mention (as long as you use fhem) is HomeMatic (WITHOUT IP!).

There you have the (easy) possibility to have kind of "repeater": the HM-MOD-PCB https://www.elv.de/homematic-funkmodul-fuer-raspberry-pi-bausatz.html

It could be adapted to an ESP8266 and then be plugged where ever necessary to extend communication to the sensors. The only thing besides a power plug: Wifi...

In difference to the ZWave "repeater functionality": it is not hopping (just once via Wifi of course but then direct communication to the sensors/actors)

If Wifi is not sufficient but cable network available: the module can also be used via LAN (Serial-LAN adapter).

EDIT: also Xiaomi could be an option. Cheap sensors (not as accurate regarding humidity my opinion / compared to HomeMatic ones). Should be possible to have Gateways where ever necessary and they then connect via Wifi to fhem. No talking home required (only if you want to use tge app)...

Have fun, Joachim

Nico94 · 29 November 2018, 20:30:17

Following your advice with difficulties of Zwave, I just look at the modules that work with the LORA protole. I have found several, including one to 100 € so I hope the others will be much cheaper!

But I do not understand how it works. Gateway are sold but there is also the possibility to subscribe to the network of an operator. Is it a requierement ? I am not able to find documentation that specifies how data is retrieved and how to exploit it. Yet I imagine that everyone gets there... Do you know how to do ?

The sensors I will give the price when I will know :

rudolfkoenig · 29 November 2018, 20:57:16

If I remember the LORA speech in Karlsruhe two years ago correctly, you can use both your own gateway or that of an operator, depending on your needs. As I dont like relying on other peoples hardware, I probably would use my own gateway. But it may happen that there is already an installed gateway in the vicinity, and it is easier to pay the fee for just using it.

Beta-User · 30 November 2018, 08:13:04

Zitat von: Nico94 am 29 November 2018, 20:30:17
Following your advice with difficulties of Zwave,

Most of the mentionned difficulties are not special to ZWave, so I'd anyhow prefere id over Homematic.
As mentionned, most of the collission issue can be avoided by using more "hand-over"-points to regular IP and split up the whole thing. As you will have to monitor the entire system closely in the end, having the multi-gateway-approach Homematic offers imo isn't a "killer feature".

You may also have a look at Zigbee (especially the relatively cheap Xiaomi devices) or BTLE. Zigbee also offers mesh - at higher frequencies thus lower range - but without the 1%-limitation @ 868MHz that may in the end cause the mentionned problems in ZWave. But this may be more tricky to install: afaik, the devices store their route throughout the Zigbee net in a fixed way, so you may have problems to get all of the devices correctly integrated and you will also need a couple of routers to allow the relatively high number of devices.
But frequency is 2.4 GHz, same as WiFi. Afaik, there are no reports on conflicts with wifi so far, but you might keep that in mind.

Zitat
I just look at the modules that work with the LORA protole. I have found several, including one to 100 € so I hope the others will be much cheaper!

I personally only have some first experience with LoRa using self-made sensors as described at MySensors.org, using a serial GW directly attached to my FHEM server hardware. Financial invest would be around 15 € per node (using Si70xx or BME280 sensors), but imo that's only a route to follow in a private environment.
I also read some material on LoRaWAN (?), where all data is provided via genteral internet using MQTT as a protocol. Might be a quite easy way to integrate things, but anyhow, also temperatures may be considered as personal data not beeing allowed to be spread, especially throughout any server on the internet.

Get yourself informed on your local regulation wrt this. Additionally, even storing that kind of data just locally may be a problem considering that aspect.

Nico94 · 01 Dezember 2018, 10:56:17

Thanks for all the details. Since it's really not easy to find a DIY solution, I planned a meeting in mid-November with a company that sells Lora sensors so I'll see what they offer and at what price.

I especially hope that we can collect the data without having to use their services to exploit them.

In France, temperature data are not considered as personal data so there is no problem. Especially since the sensors will only be installed in apartments that have accepted.

I will keep you informed of the follow-up.

Morgennebel · 03 Dezember 2018, 14:22:54

Hi Nico,

can you please clarify if you are a landlord and have multiple tenants in your building complex you want to monitor?

As if these are tenants, you may run into issues of Data privacy when deploying a central monitored solution. You will have tenants complaining about the devices, battery exchange, location, spying, etc.

In this case I would to a much simpler approach and buy one of these https://smile.amazon.de/dp/B079NQ4D54/ for each tenant, place centrally and start logging all 5 minutes. This gives you up to 12 months logging time but you need only a month to six weeks. Then collect them back and compare and sell used on eBay.

Ciao, -MN