Is attic insulation, and poor attic ventilation, the reason why your house is so hot? Probably not. There isn’t much evidence to suggest that attic ventilation will have much impact on your cooling bills. Attic fans don’t cool; they prevent moisture. More than likely, your air-conditioning equipment needs a tune up. Also consider the fact that people, electronics, and appliances are all generating heat. Recognize that it is nearly impossible for insulation to heat a home’s interior. If you’re trying to cool your home by opening windows at night, you may just be letting in humid air that your system is trying to override.
Read the full article here: Why Is My House So Hot? | GreenBuildingAdvisor.com