Weatherizing is to protect a structure against damage by the weather. Weatherizing means modifying a building envelope to reduce energy consumption for heating or cooling, involves adding insulation, installing storm windows and doors, caulking cracks and putting on weather-stripping. Weatherization is the practice of protecting a building and its interior from the elements, such as the cold, with the intent to reduce energy consumption and optimize energy efficiency. Reducing consumption of fossil fuels is important because of air quality and carbon emissions.

Weatherizing strategies include insulating pipes, insulating walls, attics, and basements, and increasing heat distribution and efficiency, such as using expanding foam for cracks, wrapping/cocking windows, and installing programmable thermostats. Most weatherizing materials are inexpensive and save a substantial amount of money and energy. The US Department of Energy estimates that over 5.6 million homes have been weatherized, saving 30.5 million MBTU of energy each year. Families whose homes are weatherized are expected to save $358 on their first year's utility bills.