"I live in the Pacific NW and want to replace my old aluminum windows. I’ve heard that triple-glazing is the new thing for energy efficiency. What is it and how do I know if it is right for me?"
Answer from Ross Sanders
Firstly, I commend you on your interest in making your windows more energy efficient. High efficiency and sustainable living are both passions of mine.
To answer your question, double- and triple-glazed windows are insulated glass units in which an inert (non-reactive) gas like argon is trapped between two or three sheets of glass that are sealed together and set into a frame system for installation. The airspace between the glass sheets helps keep cold and heat on the appropriate side of the window assembly, acting as an insulator. Triple-glazed residential windows are indeed becoming more widely available than ever before, but their increased insulation is typically suited to extreme environments such as Alaska. In the relatively mild Pacific NW, a double glazed window should suit you just fine.
Below is a graphic that should give you a better idea of how a triple glazed window works.
As you may have guessed, I am a big proponent of damage prevention and options, so I would recommend asking your designer or contractor to price out both the double and triple-glazed windows so you can make an informed decision. With that said, the payback period for the cost difference between the two glazed window options is probably going to be fairly lengthy, as windows typically only account for a small percentage of energy loss. Upgrading from old aluminum to modern double-glazed windows will already give you a huge leap in window performance.
I also want to note that frame materials play a role in the thermal performance of your windows. I would recommend vinyl and fiberglass as two options that can provide good performance at a reasonable cost and low-maintenance. Wood windows or wood over vinyl/fiberglass can also perform well but may cost more and will potentially require more maintenance such as painting and caulking.