Exactly. I will not even buy a $100 remote-internet-controlled thermostat that relies on a cloud service [0], and I've looked for both my home and my shop. I

Exactly. I will not even buy a $100 remote-internet-controlled thermostat that relies on a cloud service [0], and I've looked for both my home and my shop. I would not even consider buying the hardware that keeps my pipes from freezing if it depends on an internet connection. I'm happy if there are non-critical OPTIONS available that use the internet (e.g., as another poster mentioned, available optimizations based on real-time elec rates, etc.), but if there is any key function that'll fail without an internet connection, that's immediate disqualification, hard nope, not looking anymore. Period, full stop, even if it is "free" as in beer. OTOH, if OP can deliver a true stand-alone system and guarantees that it will never require a connection for any core function (as above, optional ok), then he'll have a large market. [0] any remote-via-internet control function should be able to directly access my IP, static or transient. Not only are non-static home IPs actually quite durable in my experience, there are a variety of easy solutions to keep track of the home IP. Yes, some of those are cloud services, but they are not tied to any hardware. Edit: That said, I'm ok with requiring wiring beyond the normal thermostat-HVAC wiring.