There is no 'negative energy', there is only lack of energy and distance from source! Don't confuse low energy with negativity! Negativity is just being negative. Negativity is localized to the physical. I'm being negative right now, but it doesn't mean I have 'negative energy' or low energy. Low (vibrational) energy is just a low level of (positive) energy. Energy is like light. Blackness is not negative light, just absence of light.
RE: 3 things about negative energy you need to know and how to deal with negativity