Air leaks often have the largest influence on the comfort and performance of a house -- more than insulation or windows or any other factor. Cold air leaking in in the wintertime or hot, humid air leaking in in the summer can make an otherwise well-maintained house feel uncomfortable. Fortunately, air leaks are also extremely cost-effective to fix!
A certain amount of air exchange with the outdoors is necessary for the health and safety of the people in the house. However, most houses leak far more air than this. A blower door test will tell us exactly how much air leakage we can seal without requiring additional ventilation.
Common locations of air leaks include around windows and doors, whole house fans and attic hatches, outlets and lightswitches, light fixtures (especially recessed "can" lights), cracks in the walls or ceiling, gaps around pipes and wires, and ventilation fans in bathrooms and kitchens.
