The cost of heating and cooling indoor air accounts for a big portion of a home’s utility bills. All types of buildings experience a continual exchange of air, and some airflow is desirable. However, minimizing excessive warm air leaking into your home during the summer and out of the building during winter should be a priority for any homeowner looking to lower their energy bills. 
 
Because warm air rises, the attic is where most of your heat will try to escape in winter. In a home with multiple stories, it is common for warm air to rise in the building leak out while cold air flows in through cracks at lower levels to replace it. When this air rises, it creates a pressure that helps push the existing air out of your home. This phenomenon makes it is especially important to air seal and insulate your attic.
 
Air sealing your attic can be accomplished in a variety of ways, all of which create barriers to stop airflow by closing cracks and openings on the building’s exterior. Insulation directly reduces heat loss and can be an important way to improve building efficiency. Adding insulation to the envelope will help reduce drafts, appropriately manage humidity levels and improve general comfort.
 
Seal up gaps so air doesn't have any easy paths to the outside, and insulate to at least R-38, the minimum recommendation for Northern Illinois.  Air sealing the attic works well for most homes. The only buildings it is not a priority for are those built since 1980, which are more likely to have sufficient insulation installed during its initial construction.  In these homes, you may want to consider adding more insulation after 10 - 15 years to fill gaps and keep your home performing well.