Quite a variety of causes are possible for "negative energy"
A few that come to mind are:
- geopathic stress e.g. being near a quarry - site of past traumatic events e.g. murder - underground stream of water carrying disturbed energies - energy line from or proximity to electronic transmitter e.g. TV or cell phone - improper relationships in the house or nearby - indigenous issues prior to urbanisation - solar systemic energy flows - ill-advised spiritual practices