During summer, the air outside the home is heated up, while the air inside the home is cooled by air conditioning. Without proper attic insulation, the hot air from outside the home gets inside, thus raising the temperature and putting an extra load on the air conditioning system. Insulation works by trapping air inside of it. This prevents hot air from coming into contact with the air inside the home. The same principle applies in cold regions, where insulation prevents cold air from entering the home