What changes does human body produce when it enters a room ?

I am making home automation model and I have few sensors installed to sense some changes in the environment to detect any changes. So these sensors provide me data , but I want to know what changes does Human body exerts on the environment it enters, so that I can install those sensors which capture these changes.

Also it would be helpful if someone can give me a list of sensors that can be or are being used in home automation projects or just to measure changes in environment.

Thanks in advance

depends also on the room.

A person radiates heat (some more some less) so the average temperature will change - DS18B20
A person breathes out water and CO2 (some more some less) so those will change - DHT22 - COZIR
A person makes noise (some more some less) - microphone
A person might produce gas (....) or have after shave etc - MQx sensor
A person takes room ( ... ) so air starts to move more - different
A person might block the light
A person opens a door
A person will go through an entrance that can be guarded

Enough ideas to get started?

Opening the door or walking into the room changes the pressure. I have seen a circuit that uses an electret microphone and a low pass filter to detect the change.

Weedpharma

Capture changes in infrared radiation: Passive infrared sensor (PIR).