This study from Harvard University's School of Public Health shows that if the 46 million existing single-family homes in the United States that have inadequate insulation were retrofitted with additional insulation to meet the 2000 IECC, the benefits would include 240 fewer premature deaths, 6,500 fewer asthma attacks and 110,000 fewer restricted activity days per year. This translates into a potential savings of $1.3 billion per year in averted costs such as health care, and $5.9 billion per year in additional savings associated with reduced energy consumption, paying back the initial cost of the insulation in about six years.