about the temp and humidity sensors…I was more thinking about the difference between the actual room temperature and the in-wall temperature. But hopefully it won’t be too far off. Speed is of course not much of an issue (although it should be able detect an open window sooner than in half an hour 
). 7 RGB leds, how will you remember which means what? Labels on the panel?
Hey Marek,
the seven LEDs all show the same color, so you only have intensified brightness. There will be only two or three codes, therefore it should be easy to remember.
@CeeCee: Like your thinking and work! 
I am new to OH, currently owner-building my new home (passive house), and did some serious thinking on how to implement a home automation solution in principle… and funnily enough, came up with the exact same thinking… except for one point: undo-ability.
I also had the idea to reduce cable runs by installing room hubs / boxes.
However, I could not see a point in either undo-ability or installing light switches at all.
I would have installed configured a rPi, Arduinos, 24V LEDs, locked down the software once all is working; keep spare hardware, and would then let the system run for decades to come.
Since this is my last house, which I will only leave in a coffin, I did not care about resell value at all.
However, actually installing a light switch (and if it is only one per room), and running 240V sized cables, ripping out the automation, or replacing it in many years to come with something else, struck a chord with me – after sleeping a night over it.
Thanks you for sharing your thoughts – I do appreciate it… and also enjoyed finding a like-minded brain
I also want to thank the OH community for their work, and their support, in particular Rich, sihui, Udo and others for contributing some very insightful posts, and helping me out with newbie questions; I would have left OH on a way side without them!