Extra strength sage to burn and smoke out old energies in the environment and our personal energy fields. 
It is said the spirit guides of the plant come in to do the work and you merely need to offer it with the intention of clearing. Fill up the space with smoke, then open the window to let it out. It soaks up like a sponge, so be sure to clear the settled smoke. Then fill it back up with some light Insence to seal the room back up.