A:Answer Hello, Yes, you need to run the hose out a window. The unit blows out the Hot air. Without venting it (putting the hose out the window) you are just blowing that hot air into your room. Every A/C will have that same issue. Also, note that the Unit needs to be close to the window as the Hose is only so long and is over 5 inches around. IF you can live with that, this is a great unit and will keep your room cool, but your electric bill will go up.