I am looking for a expert. I have recently stumbled upon the hubitat smart home hub, and i was wondering: what is the data privacy, why does the hub need to be connected to the internet if the processing and home automation happens on the device it self. What is the cloud it is connected to.
(sorry for bad english, its not my first language)
cloud is only for Alexa/Google Home functionality and your remote access via Hubitat Dashboard. If you don't want need any of those 2 items, you can block internet from hub and it still runs. Hubitat never collects or has any access to your data
As best I understand, you need Internet support to be able to update your operating system to the most current release. You also need Internet access if you plan to use the mobile app. Finally you need it if you plan to want cross platform interaction, like Amazon. After set up and registration and if you don't want all the other things like I described, you can pretty much run without the Internet. Others please chime in if there are other things that I missed.
thank you very much for your reply
Well, technically not just Alexa/Google home... Any cloud integrations. Life360, sharptools, etc. Which really should be obvious to the end user, of course.
I've seen it mentioned too that the Hubitat relies on internet-based time server and that time gets messed up quickly if not able to access a time server.
You also need an internet connection to set the date and time on the hub properly. It reaches out to an NTP time server(s) to keep its clock up to date. If you reboot the hub, without an internet connection, it will not know the correct date and time, and thus any automations that depend on date and time will not function correctly.
There is a workaround for this, as Hubitat has exposed an API to set the date and time. A community member wrote a device driver that can obtain the data/time from a local NTP server and update the hub.
The following are the things that won't work without an Internet connection, but the hub itself will definitely work for all local control:
The cloud it is connected to is a Hubitat server, cloud.hubitat.com. Whether it is AWS, GCP, Azure, or something else, I have no idea. I don't believe the HE team has ever said? The DNS resolves to cloudfront.
I thought this worked regardless of whether or not the hub is connected to the Internet, assuming the location of the hub is set correctly and you keep the date/time updated? Have you tested this? I am simply curious... 
Yup. I believe it has been stated by HE team that this is a calculated value.
Hmm I haven't tested. I kind of assumed and knew ST required their lighting automations to be cloud once sunset/sunrise got involved. I think you need more than lat/long for sunrise/sunset. You need the declination of the sun too. I guess you could store a table with approximations of that, but they change slightly each year...
Edit: Sounds like you're correct Sunrise/Sunset time wrong
where can i find the data privacy thing
What is a "data privacy thing"?
if they sell your data or not
how much privacy you have and if they are surveying you
Not sure what you're asking, exactly... (by the way, I do not work for Hubitat... 
)
Hubitat's policy, though, is that they do not collect any user data, nor do its employees have access to your user data. Their cloud server is simply a safe, secure, cloud endpoint to allow integrations with cloud services, like Google, Amazon, Ecobee, etc... They do not store any of the data that passes through this encrypted endpoint.
Among other things, this keeps their costs down.
Tagging @bravenel who works for Hubitat and can directly/officially answer your questions regarding data privacy.
You can read their Privacy Policy here, when purchasing a hub from their web store...
thank you very much, that was exacly what i was looking for 
Download the Hubitat app
