Re: Nest controllers
If anyone had told your friends, or they themselves had done some homework, they would have discovered that Nest devices only work when it has internet access - once their internet is down, you have no manual control of the system, even manually from the device itself. It is locked into the last setting until it gets internet again.
In Amerika we have the Honeywell controllers, which are autonomous with internet control added, rather than internet devices with manual convenience controls.
So, as usual, the most-known, popular device is the worst choice for an individual's continued independence.