Simply put, insulation is material used to help your home trap heat and retain warmth during those chilly winter months. If you live in a hot climate, you might be thinking, why do I need insulation? The answer is that insulation can also help keep heat out and cool air in, making your home more energy-efficient — and, as you’re sure to notice on your monthly electric bill, more cost-efficient, too. Insulation can inhibit the growth of mold and mildew, which is a bonus in hot, humid climate.