Reading signal (Status) for a KNX 4 binary input

How do you make sure the rooms are occupied(what devices are in use for that)?  Basically it should work if you use some movement sensor+light sensors to make sure if there is someone in the room. You could also do a visualisation where the admin activates the inputs when they give out the key? I would make a visu with two objects 1) button 1 for keycard has been given out 2) activity monitor that gives out a status when there is a movement. 
But reality is no admin is going to watch it... Would be nice to know how do you make it work. Cheapest version imo would be a simple PIR that gives out the status. But i dont think it's the best way to go though.

Hello Dear,,

A lot of thanks for your suggestions &  support,, 

Regards,, 

Hi,

How do you control the rooms entry?

Do you have some sort of energy saving switch card holder for the room?

Probably I would think of using some RFID / NFC based switch card holder, to assure that the room would only get power / unlock the circuits with a valid RFID / NFC. This is to avoid using any card on the card holder (like a credit card etc), so in practice only the correct card would "unlock" the energy to the room.

So, without any valid card, you can block all circuits, all shutters, etc, even use a contactor to cut the power of the remaining circuits (outlets, air conditioner, etc). Without any energy (just for the mini bar), the room is almost "useless".

With this, you could connect the card holder to binary inputs, and get the input status of the card holder. If there's not any card inserted, probably there's no one using the room. Well... at least without any energy...

So you can think: "ok, but someone can enter and not insert the card on the holder, and use the room without energy". Probably, but the room is almost "useless". But you can combine the card holder with some sort of ultrasonic presence detector, like the STEINEL ones, with 360º detection. Never used them, but they look very promising... (I'm not affiliated to any brand!)

https://www.steinel-professional.de/en/sensors/presence-detectors/us-360-knx.html

I guess that you need to think about a combination of different sensors to get an almost "perfect" occupied detection.

Best regards

Dear Ricardo,, 

Thank you for your support,, 

You have explained and suggested,,  what i am thinking about,,  

Simply i will use a Card Holder with binary input,  as i first offer for the client.. To know if the room is occupied or not.. 

And regarding the ultrasonic sensor, thanks again for your suggestion,  so that i will take it into consideration,, 

Best Regards,,