If you truly can’t tolerate connecting something to the internet, at least for initial setup, ruling out Ecobee (which I think is the best choice and supports local control via HomeKit protocol), then a Zwave thermostat is likely your best bet. Can’t recommend one because I haven’t used any (despite having a Zwave network and a ton of Zwave devices, because none of them looked as good as Ecobee when I was searching years ago).

You have three suggestions for ecobee, which no longer integrate well with home assistant other than homekit which is a very limited integration.

Based on your requirements you may want to look at venstar thermostats. They have a local api, and are wifi, which isn't a very common combination. Many people who want local only seem to go with the Honeywell t6 pro. Its a nice thermostat. I have had the t6 and the ecobee.

But perhaps you can share what features you are looking for? Is it just control, or historical data?

ecobee

Another Ecobee vote here, works great with the HomeKit to Home Assistant integration, along with 5 additional room sensors. Does everything I want it to.

any particular model of Ecobee?

GOOGLE THERMOSTAT TOTALLY SUCKS …. Mine didn’t last even a year. They are trying to dump a “revamped” one on me in exchange.

They are even phasing out support from what I understand (…the 3rd generation Nest Learning Thermostat has not been formally discontinued as of late 2025, but its support is ending; Google is retiring older models (1st and 2nd generation) while still supporting the 3rd gen and Nest Thermostat E for a while longer. However, Google is offering users a discount on the 4th generation thermostat to migrate to the newer model before the 3rd gen eventually loses smart features)

STAY AWAY FROM THESE CROOKS

I know the Philips Hue motion sensors also sense temperature.

Can you not just set a routine where if the temperature reaches X, trigger Y?

Time ago I used Tapo sensors with Google Home, they require their own hub though like the H100. I still use them but in SmartThings, they have both cloud and Matter integration and have been quite reliable.

If you have Thread support in your network (Nest Hub 2 gen for instance, Google TV Streamer, etc.) you can also get the Aqara W100, but that's going to be more expensive than the Tapo T310/T315 + H100 hub.

WiZ is also compatible with SmartThings so you have the option to create the automation there should you encounter issues with Google Home. Since it supports cloud integration, no SmartThings hub would be needed. And, unlike IFTTT, it's free, IFTTT now only allows two simple "applets".

Although I didn't see a direct question, I'm assuming that you're asking for thermostat options? Home Assistant can easily manage all of the other devices you've mentioned. You definitely need to ditch Google Nest and move towards having everything local.

As far as thermostat recommendations, if you want local control, you should consider Ecobee, Honeywell T6 Pro Z-Wave, Emerson Sensi and/or Venstar. Pretty much anything Apple Homekit is a good choice as well. I'd avoid the newest Google thermostat. Even though it supports Matter, its mandatory that you use the Google Home app in order to set it up. If they sunset that device, you won't ever be able to add it anywhere else in the future.

Edited to add, I personally have and use both the Honeywell T6 Pro Z-Wave and the Emerson Sensi thermostat in Home Assistant. Both are running locally (no cloud necessary).

I’ve heard the Ecobee is the way to go. Also heard that Honeywell makes a great one that’s slightly less appealing-looking, but very functional. I’m currently using the Nest until it dies (probably).

Sensi Touch via Homekit and a Honeywell T6 Pro Z-Wave t-stat.

Ecobee, hands down

Honeywell T6 Z wave. It’s very reasonably priced and does more than any other can - also completely locally without needing any other service to operate. Hands down for Home Assistant this is the one you want. No depending on someone’s API for the integration to work!

I got the Honeywell T-6 Pro Zwave model, which a lot of people here recommend. Seems good so far.

(Have to get the right one, they don’t all come with z-wave.)

I imagine the primary con is that it's cloud based, rather than local. I think the pros are that it works well outside of home assistant as well, in the Google home app. I use two of them and am the home assistant integration maintainer, so let me know if you have questions.

I don’t know about the Nest but I like my Ecobee

It works, looks sexy, and basically free with utility rebates and current BF and Cyber Monday sales.

Getting it into HA was easier/straightforward by way of homebridge, and saves $5.

My "smart home" was built in the beginning of this year and most of what came with that package was garbage that I eventually replaced. But not my Honeywell T6 Pro ZWave thermostats. I consider myself very lucky the installers chose that for their package. If you can dump the cloud/app connected stuff for Zwave you'll probably be a lot happier in the long run.

Anything Zigbee or ZWave for 100% local control, then use HA to handle your programming/smarts. I'm using a Honeywell T6 Pro ZWave (the wifi version sucks balls). I moved from the Nest thermostats due to the jackassery Google pulled with their API. I don't want to lose access to my own thermostats on my local network ever again. I have 12 temp/humidity sensors around the house as well as outside. I use a few simple scripts to reset the temps and make adjustments for home/away as needed with person detection/room presence. When it's 100% local, you can program it as complex or as simple as you need. There are several guides available out there and I'm sure we'll see a few chime in with their projects they've built.

I am somewhat frustrated by the lack of colour in Google home, because seeing e.g. what is on or off can be difficult, especially since lights and plugs use different colours.

It may be possible to improve this by forcing different (black/white) colours in Material You (via background wallpaper etc) but I've yet to really try this. And this might mean that different people are having different experiences here.

So, while it's not a deal-breaker, Google Home is one of the things that makes me sometimes wish for colour eInk, if black/white optimised apps aren't available.

..

I have a Google Home setup with Nest cameras, doorbell and thermostat. The HBP works really well except I couldn't get doorbell camera previews in my notifications.

I've had an Emerson Sensi for several years and works very good with no issues. Phone app is adequate and simple, and local control interface is good. It was one of the least expensive smart thermostats I could find at the time. Only issue I have is I would like more detailed historical data.

I had 2 Ecobees for 5 years in my last house with no problems. The A/C guy said it was a good choice because they were always needing to work on the other brands, particularly Nest. They didn't have issues with Ecobee.

I've had a Sensi Touch for a couple of years now and it works well. 100% local (no cloud) via the Homekit integration in Home Assistant. Honestly, I rarely see or even touch it as I use Home Assistant for control via multiple dashboards throughout my home and also use my phone when out and about.

Nest

my idea for reference

Ecobee Smart Thermostat Premium : Loaded with extras (occupancy detection, Siri/Alexa too), sleek design. Worth it if you want top-tier tech. Amazon link

Ecobee3 Lite: Budget-friendly, solid basics (remote app, voice control). Great for smaller setups.Amazon link

Emerson Sensi Touch: Super easy to install, killer touchscreen, and plays nice with SmartThings. Amazon link

Honeywell T5: Cheapest option, geofencing rocks for energy savings. Amazon link

Detailed Comparison blog

I’ve had Nest for years and Ecobee for years and I believe the Ecobee is a better experience. Overall, they’re all kind of the same. The “smart” auto change features never really hit the mark and at least for me I end up doing a manual schedule and basically leaving it alone. I do like that I can connect Ecobee to HomeKit so if you have iOS devices you can use Siri to change the temp.

The new thermostat you get will have this plate where the wires connect. So you don't have to worry about finding one compatible with this place.

So really any smart thermostat will work. If anything you MAY need to check the wire configuration on the board at the Air Handler, especially since I see a Blue wire where a Yellow would normally go.

That said, Ecobee and Nest are the usual go-tos for most, but there are Honeywell smart options as well.

Ecobee controlled locally through HomeKit. No Apple products needed. No internet connection needed. Don’t even download the ecobee app.

I installed a smart thermostat myself, so I’ve gotten a bit familiar with thermostat wiring. From your pic, I don’t see a c-wire, which most smart thermostats need, but sometimes it’s tucked behind, so it’s worth checking inside the wall plate jic. Even if you don’t have it, you can still go for a smart thermostat using a c wire adapter. I went with the smart thermostat eco from cielo because i was already using their controllers for minisplits. It came with the c-wire adapter in the box,  no extra cost. I used that during installation and it all went pretty smoothly. Also, the Cielo mobile app is super user-friendly. If you’re on fence, I’d definitely recommend looking into it.

I'll put a big vote in for ecobee.

I replaced my 3 Honeywells with them. Upstairs, I have remote sensors in each guest bedroom, where the thermostat itself is in a common area.

I did need an ecobee rep to help with the installation. She stayed on the phone with me for the entire duration. -First rate service!

I think their app is great. It has so many capabilities. I also have it integrated with my Hubitat Elevation hub and Alexa.

When I got my Nest thermostat, I also got a Nest temp sensor. They both work seamlessly with my Ghome

It would be great if the Google Nest had an inbuilt temperature sensor. I had a quick look and unless I am mistaken the Tuya does not work with GH?

I can ask the Google home what the current temperature is in the room where my Nest thermostat is, but I don't know if you can address the seperate Nest temperature sensors.

I bought two of these: Lilon Tuya ZigBee Smart Temperatur- und Feuchtigkeitssensor Tuya/Smart Life App Batteriebetriebene ZigBee Smart Home-Sicherheit https://smile.amazon.de/dp/B08T9C2JDW/ref=cm_sw_r_apan_glt_i_NEA9TJ6QM7X2SCWFTWZB?_encoding=UTF8&psc=1

i have them connected to the Zigbee Hub and use normally the Smart Live App. I recently started using Google Home and just linked Smart Live to Google Home. In Google Home they show up and i put them in a Room and if i ask Google for the Temp of the Room it tells me the Name of the Sensor and what Temp it has.

Did you ever find a solution? I’m looking for a temp sensor for babies room.