Buildings are a no-go for me.
Unless you've had significant levels of training and have four or five buddies all with the same level of training, level IV armor and some real life experience, going into an unknown building is a good way to get dead very quickly.
What do you think would happen if someone tried to enter your "empty" house while you were still there?
I agree. Even with the training, armor and weapons, room clearing is so dangerous I hate to do it even in simulation. Unless it was *absolutly necessary, I would never room clear, especially without my team. If I definatly had to, I want my M249 SAW back! Cut apart the door and sweep at waist-level through each room massaging the trigger, cut anyone who was in there in half. Perhaps throw a pipebomb or homemade grenade in first. It's dirty, but it works, and whoever is inside (good, bad or indifferent) is getting killed, but it works.. which is why I'd never want to do it!
If I didn't feel like I needed to kill anyone/defend myself, I'd simply announce my arrival verbally and list my intentions (while behind cover and concealment). If the situation isn't that permissive, unfortunatly, who ever is inside is going to have a very bad, very short day.
-spike