Five Room Escape

This is a very nice house and there are five rooms in the house. I was told that the owner of the house had built it but he had never come to live in it. On hearing this I thought that the house would be a perfect place to live in for some days as I was new to this city. I was so wrong. I am trapped inside this house and the exit was locked automatically the moment I entered the house. However, my instincts tell me that there must be a key somewhere inside the house but I know that it will not be easy to find it. I have no choice but to go for it.