Stack Effect, created when hot air rises, results in a lower pressure in the basement and first floors, drawing air in through windows and doors. For every cubic foot of air that leaves the building (Exfiltration), another cubic foot of air must enter (Infiltration).

Improvements are categorized under  Envelope, Baseload ElectricalHVAC, Hot Water Heater, and Renewables

 Common Envelope improvements include Air Sealing, Insulating the attic plane, band joists, foundation walls, and above grade walls. ERVs or HRV's may be an option for tight homes. Duct Leakage can be a major cause of energy loss.

Think your windows and doors are leaky? Guess again! It's more likely due to the larger gaps in the attic or basement that drive the Stack Effect, which pulls air in through the windows.

Typical Baseload energy measures include lighting upgrades, upgrading an inefficient refrigerator, motion sensors, and home energy monitors which provide a 24 hour measure of your electric consumption. 

Common HVAC improvements include sealing/insulating ductwork, installing outdoor reset, testing and tune-ups, or HVAC replacement. 

Common Water Heater improvements include fuel switching, installing  low-flow plumbing fixtures, insulating hot water piping, and possibly upgrading your water heater.

Renewables include Solar PV or Solar Domestic Hot Water Improvements.