Very recent case.
When a large gap between two buildings facing your back or front of your house, it created an invisible Sha Qi Killing Qi. This Sha Qi can be enormous when the buildings are large and the gap is narrow.
This is what we called "Heaven Blade Sha". This will create a rushing Sha Qi towards your house which results in poor health and lead to financial problems.
It can be disastrous especially for elders, children, the sick and the weaker occupants.
A good example as shown below.
The two tall building was new about 2-3 years old. Within less than two years, there were three deaths (two accidents, one blood cancer) and another suffered from stroke in the four houses with their back facing the gap.
The is a swimming pool just behind these four houses making it worst.
These are the type of houses you must avoid.