There are many types of windows that are energy efficient, but the most popular type is the double-pane window. A double-pane window has two panes of glass instead of one, and this helps to keep the heat in during winter and out during summer. Additionally, newer windows often have a low-emissivity coating that helps to keep the warmth in even more.
There is no definitive answer to this question since there are many factors that affect a window's energy efficiency, such as its type (single or double pane), age, and weatherization. That being said, most experts agree that windows with low-e coatings are the most efficient. Low-e coatings are special types of coatings that help reflect heat back into your home during the winter and keep it out during the summer. They can be applied to either the inside or outside of a window, depending on where you live and the climate conditions. If you're looking for a new set of windows and want to ensure maximum energy efficiency, be sure to ask your installer about low-e coatings.
