Noun, する verb, and の adjective
かんき
ちょっと窓を開けて部屋の換気をしない？
Why don’t we open the window and air out the room?
Something that will exchange energy is something that pulls in air, takes out the bad stuff, and then outputs good air, exchanging it for the bad. That is ventilation.
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.