Energy hauntings can be the most fun. They are nothing more than collections of energy, with no real conscious intelligence. Of course, they can exhibit the behavior of other types of hauntings, especially spirit or entity hauntings. Over time, the energy collects from various sources and events, slowly (or, under some circumstances, quite quickly) producing enough energy to start randomly causing manifestations.
As time passes, and the proximity to living people and other intelligent forces accumulate, the energy will begin to mimic those essences. It is possible that over a long period of time, energy collection and exposure, such an essence could possibly take on its own existence and life.
Energy hauntings can be one of the most difficult types of paranormal activity to properly identify. As it often mimics spirit or entity hauntings it can be all to easy to be mislead into getting wrapped up in a situation that is only a mirage, often causeing the situation to worsen.