Results of this analysis demonstrate that a number of existing window retrofit strategies come very close to the energy performance of high-performance replacement windows at a fraction of the cost.

But for others who are facing this decision — and there are an estimated 50 million homes in the U.S. with single-pane windows, so I know you’re out there — I have important information: A new study [PDF] from the folks at the Preservation Green Lab, a program of the National Trust for Historic Preservation, found that retrofitting windows can save nearly as much energy as replacing them, and costs much, much, muuuuuuch less.

The study, which compares various window scenarios across various climates (Boston, Atlanta, Chicago, Phoenix, and Portland), confirms what those in the world of preservation have been politely suggesting for some time now: old panes beat new panes. You can find out more in this helpful overview from the California Office of Historic Preservation.

So what is this “retrofitting” of which we speak? Well, it can be a fancy task undertaken by trained professionals or ambitious DIY-ers, involving things like insulating counterweight pockets or installing new suspension systems. Or — and here is the good news — it can be an unfancy task undertaken by people like you and me, involving things like installing storm windows, hanging cellular shades [PDF], and adding weather-stripping. The new study has some helpful pros and cons for each of these options, and emphasizes that other energy-saving steps around the home are also important.

Read it via Ask Umbra: Is retrofitting windows better than replacing them? | Grist.