As Building Analysts we think of the House as a System. The idea is that all components of a house are interrelated; changing one part without thinking of how it effects the others can create a domino effect with negative consequences.
For instance, there is something called the stack effect which occurs in a house (this is convection) — hot air escapes through the attic which creates a negative pressure in the house that causes cold air to infiltrate through the bottom floor and basement. Air passes through cracks in walls, past insulation and building materials. The solution is to air seal and insulate the house to slow down the stack effect. BUT... Over tightening a house through can cause a furnace to backdraft spilling CO into the home that can causes health problems or even visits to the hospital. So, we think about all aspects of the way a house works in a holistic manner so that something that fixes one problem doesn’t create another, potential more serious problem.