With the process of building the house, I'm building the list of smart house items:

Family Label Description
House Communication There are many smart house systems, wired (KNX, DALI, DMX) and wireless (ZigBee, Z-Wave, WiFi). Each has advantages and disadvantages.
Smarts There are many systems that add intelligence. HomeAssistant, Loxone, Gira are just some of them.
Ventilation The people building your house should know about this. New houses must have ventilation by law. You can add a ventilation system to an old one...
Sensor Water detection There are flood detection, humidity detection sensors. If you go with wired sensors, consult an expert.
Leak detection Leak detection sensors are installed on the main intake usually. This might be limiting.
Motion Motion sensors can help a lot in the feeling of a smart house.
Presence Presence sensors complement motion sensors (e.g. thermal detection).
Open/close They are useful if you forget your windows open
Camera Indoor Indoor cameras are optional and may create contractual issues with the e.g. cleaning company.
Outdoor Outdoor cameras are part of your security system. You can also use them to enhance the smartness of your house if you can detect motion
Temperature Thermostat This can be smart (think Nest) or dumb (just a dial). You can complement it with the house smarts.
Electrics Lighting Lighting is easy and fashionable. Wireless systems (e.g. Philips Hue) work well. DALI or DMX are better IMO, but also more expensive.
Sockets Power-measuring sockets are very useful IMHO. Unfortunately, the offer is rather limited
Monitoring Power monitoring solutions at panel level are popular. Unfortunately, they are not too granular and inferring device usage is problematic.
Audio There's a wide range of audio devices which can be integrated in the smart house. Sonos is arguably the more popular (DIY). Integrators have high-end solutions.
TV Most TVs are smart-house friendly. Check your smart house system first for compatibility with the TV (unless you want to contribute).
Projectors Same as TVs above
Doorbells There's a wide range of doorbells, connected to the internet (or not). Decide if you want to be able to talk to your postman from holidays or not
Locks There are a lot of locks. Wired, wireless, with fingerprint, dial, contact-less... Pick your poison, or pick a classic one.

HTH,