Ventilation is the V of HVAC that often gets forgotten. It is important for every home to have a ventilation strategy to ensure occupants have clean, fresh air in the home. In older existing homes, by default this is air leaks through the building enclosure i.e. walls, floors and ceilings. That air is not filtered or conditioned so it can create health issues in the home like asthma. This is why new construction takes on the motto, “build tight, ventilate right.” Controlling where the air comes from helps create a cleaner, healthier indoor air environment. A balanced ventilation system is the best solution because it minimizes uncomfortable pressure imbalances by bringing in fresh outdoor air and exhausting stale indoor air. through a heat exchanger core in a heat recovery ventilator aka HRV or through a separate supply in the heating system and exhaust fan. The benefit of the HRV over the two part system is that the heat exchanger core transfers the heat of outgoing air in wintertime to incoming air so the furnace doesn’t have to work as hard.
***One other really important thing you can do is check that every bathroom, especially those with a shower, have a bath fan that is directly sealed to the outside through the wall or via ducting through the attic. Too often, during a home assessment we have seen fan ductwork laying amidst insulation in an attic creating mold issues on the sheathing.