Air Sealing is important for homes in New England. Not sealing the air coming into your home will cause home outside air to enter homes. Air Infiltration occurs when outdoor air enters a house through cracks and openings. Homes in which proper air sealing is performed with cracks and openings sealed can significantly reduce heating costs during and cooling costs in the summer. Air sealing is performed by caulking, weather stripping and using foam insulation in leaky areas.