Duct leakage, exhaust fans, air barrier penetrations in a building greatly affects the pressures. It will also cause uncomfortable zones and increase utility bills. Something as simple as a manometer can provide detailed information. High positive pressures result in return air duct leakage. Negative pressures means you have supply duct leakage.
As a building analyst we can balance your home or office for a much better climate zone. Pressures also effect the behavior of gas / oil fired equipment. Within medical facilities "hospitals" pressures should me monitored and tested annually. Testing building pressures and acquiring a baseline is the starting point when conducting an assessment on buildings.