To prevent heat escaping through the attic and the walls of a home fiberglass batts have been a traditional insulation. New advances in insulation offer a better solution that is easy to install and on the budget.
The contemporary best practice is expanding spray foam insulation installation. Foam fills the cavities in between the framing studs of the walls and attic. Spray-on foam expands to fills in air gaps, unlike standard fiberglass insulation, which lets air pass through and around it. Even as a house expands and contracts the foam insulation expands and compresses with it. This prevents warm air from escaping through cracks and spaces.