Many homeowners use argon gas in windows to increase the energy efficiency of the windows. Window manufacturers put this type of gas in between the panes of the windows because it is heavier and denser than regular air. Its density helps keep air from coming in from the outside, and it helps keep air from escaping from the inside of the house. This helps your home's heating and cooling system to operate more effectively. It will help you keep your home cooler in summer and warmer during cold winter months.