Since the HomeKit app, Home, for iOS was shipped with iOS 10 it was time to check its possibilities.
After some checking the products from Elgatos Eve seemed to be a way to start. They also have a free App which I like. The disadvantage is that they are Bluetooth devices with a limited range and therefore have to be pretty close to an Apple TV.
I started up with the Eve Room, indoor sensor, and Eve Energy, switch and power meter, and the Apple TV 4 as Home hub.
Apple have god instructions here and there, read them, but first update the firmware of the accessories, in this case via the Elgato Eve app, otherwise the Home app will probably not recognise them.
To avoid additional problems don't forget to set up the two-factor authentication for your Apple ID, and then log off Your Apple TV:s iCloud account and log on again
If everything is set up in a proper way your Apple TV automatically sets itself up as a home hub.
There are limited HomeKit accessories available, but if You have a decent knowledge of Raspberry Pi, You can check the software reported in this post where all Z-Wave and/or Telldus Live devices can be a HomeKit accessory.