While single-pane windows have a single layer (your regular old-fashioned glass window), double-pane windows are made up of two layers of glass, with a space in between that can be filled with a certain type of gas (usually argon or krypton) in order to insulate the temperature inside the house.
Not everything is perfect when it comes to double pane windows.
A huge precaution to have in mind when replacing a single-pane window for a double-pane window is that, in order to show a significant reduction in energy, you absolutely must upgrade the entire house. Replacing a single window won’t have a noticeable impact on your energy savings. If you have a home that was originally built with single-pane windows and can’t afford the very expensive investment of changing all of them simultaneously, it’s better to keep the original windows for now and save up for double-pane windows in the meantime.
And of course (like anything involving construction): QUALITY MATTERS. A poorly fabricated double-pane window will most certainly cost more than what it saves in the long run. From failed seals, to incorrectly spaced panes and shoddy manufacturing, being cheap when buying a double-pane window may cost way more than you bargained for. Quality is fundamental for double-pane windows to work properly.
Nevertheless, after reviewing the pros and cons of double-pane windows, the answer is YES! If one takes the precautions necessary to buy good quality windows, double-pane windows are absolutely worth the investment.