Wasting Money On New Windows?

Is an investment in replacement windows really worth it?

  • Author's Note: In the interest of full disclosure, I (Mike Bruno) sit on the Historic Preservation Commission for Geneva, IL. The opinions here are my own and do not necessarily reflect the opinions of the commission or the city of Geneva.


In the context of historic preservation, few topics can be as contentious as “new window” vs. “old window.”

There is a fairly broad public perception that the bodies regulating historic preservation in Geneva are unreasonable in demanding that property owners keep their “old drafty” windows in lieu of “new energy efficient” windows. This has become especially acute in this time of green initiatives and high energy prices. I hope to demonstrate here that—despite what window manufacturers would tell you—there is often no practical advantage to replacing your vintage windows.

This post will focus solely on the economics. A later post will focus on historic and aesthetic value of older windows along with the merits and shortcomings of old and new materials.

Physics informs us that there are two ways to lose energy through a window (or any other exterior house component.) The first is conduction where your precious interior warmth soaks into the walls and windows of your home and is radiated out to the environment. We typically mitigate this with materials that slow down that conduction such as fiberglass insulation in empty wall cavities to increase its “r-value”. (Interesting fact: it is not the fiberglass that is the insulating component, but the air trapped by the fiberglass that does the insulating work.)

The second vector of energy loss is through air infiltration, where gaps between exterior components allow air to flow freely between the interior and exterior of the building. In the case of older, unmaintained windows, it is the latter that represents the majority of heat loss.

Up front, I will acknowledge that if you have a 100-year-old window that has never been maintained and does not have a storm window, you probably are losing energy unnecessarily. The popular mis-conception is that the only way to address this energy loss is through putting your old windows in a landfill (the opposite of green) and writing a very large check to your window retailer. Such misinformation seems willfully propagated by those that profit from new window sales and installation. This is often accompanied by (necessarily) vague assurances that you will save enough money in heat and cooling to send all your kids to college. Let’s take a look at how window replacement can be a costly and ineffective effort for the homeowner (but a terrific solution for windows retailers.)

Probably the biggest red herring of the deba—and easiest to debunk—is the promotional claims pitting single-pane against multi-pane glass. To be sure, multi-pane glass does have a higher insulating value. But we must consider that a double glass pane has an r-value of just 2 compared with a single pane’s r-value of 1.

Unless you have windows floor-to-ceiling and corner-to-corner, simply replacing an r-1 material with an r-2 material will not appreciably affect the insulating value of the entire wall that might only be 15 percent windows. If we consider that the largest single vector for heat loss is the roof, we might typically calculate a percentage of overall energy savings in the low single digits on the virtues of multi-pane glass alone. You’re not going to extract any college tuition from those sorts of savings. This doesn’t even consider the option of simply adding a well-fitted storm window creating its own double-pane effect. But more on storm windows later.

As I said before, the vast majority of heat loss through older, un-maintained windows (and improperly installed new windows) is through air infiltration. If a homeowner is even remotely handy, that air infiltration can be cut by 80 percent or more for under $5 simply by application of some simple weather stripping between sash and frame and requires no power tools.

It should be understood that older windows were designed to be user serviceable. Contemporary windows are typically monolithic in design with little or no option for user maintenance. There is no question that the old wood-on-wood sash-to-frame contacts leave ample space for air (and energy) to pass. There are solutions to improving these seals that can get quite sophisticated that achieve parity with the finest new windows. If you are not particularly handy, then there are local companies that specialize in window restoration that can get your windows operational and weather-tight for less than the cost of a high quality replacement window. (We will visit LOW quality windows and their hidden cost in a future post.)

So once you have your old windows weather tight, you can still get the benefits of double-pane glass through the addition of well fitted storm windows. These don’t have to be expensive. Perusing the Home Depot website, they range from $30 to $53 for the aluminum multi-track models. I know, I know—they don’t look nice! I am not promoting aluminum storm windows; I am only focused on economics here for this post. 

Given what we know so far, a reasonably handy homeowner can invest less than $65 and a little time and get all of the energy-saving benefits of a high quality replacement window (which can start at $500.) A more aesthetically pleasing (though still affordable) wood storm window can be procured from companies like Adams Architectural Millwork Co.

This merits a little digression here on aluminum storm windows. Geneva’s Historic Preservation Commission (HPC) often receives incredulous reactions when petitioners hear that “ugly” aluminum storm windows are permitted in the Historic District. There is no question that one would be hard pressed to describe extruded metal storm windows as an “architectural feature," but this speaks to an important premise in HPC decision making. Of primary concern for the HPC is that the change be reversible. While you won’t show up in any preservation or architectural magazines with metal triple-tracks, the window can be returned to its original form by removing the metal storm window.

To wrap up, you might be in an old home (such as many in Geneva’s historic district) with windows that are already in the vicinity of 100 years old. Window manufacturers can only stare at their shoes when asked if you can expect a similar service life. Old windows can often be made every bit as efficient as a high quality new window for well under $100 and can provide another century of use. Studies have shown that, on average, contemporary windows are replaced every 16 years. If you are looking simply to save money on energy and live more comfortably, it is very difficult to make the math support new, high-quality windows that might well exceed $500 per unit.

Next time: Historic vs. contemporary materials, artisanal millwork, historical manufacturing processes, and architectural character.

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Colin C. March 05, 2012 at 05:11 PM
Mike, Yet another fantastic article. You should compile these into a book when you are done. Back in the 1970s days of energy conservation I studied a lot and opened a small business consulting with home owners on cutting energy costs. We built “sunspaces”, “super-insulated” houses and all the rest but we found that the average homeowner can accomplish a lot with a few simple and inexpensive steps. We have done this with our 1866 home in Geneva and cut our costs by more than 1/3 for very little money and time spent. 1. Air leaks are far more important than insulation. Get a powerful window fan, install and turn on, close up the house, and light about 5 sticks of incense. Start in the basement; go around the entire foundation, every window, crack, wall penetration, gap--everywhere with the incense. Leaking air pulled in by the fan will blow the smoke. Seal the leaks with caulk, expanding foam, whatever is best. Do this through the whole house. You will be amazed at how many leaks you find. Be careful! Don’t set anything on fire please! (continued)
Colin C. March 05, 2012 at 05:11 PM
2. Create an “airflow management” system. With today’s A/C we do not need to open many windows at all. Of the 32 windows in our home 25 are permanently sealed, most also have wood sash storms that are also sealed. We can open 3 downstairs doors and a window in each bedroom. When we want outside air we open these and turn on that window fan. So we have R-2 glass and a 2” dead air space in most of our windows and no condensation problems. The best part of this is that it works, was cheap, and does not change the historic nature of our home.
Mike Bruno March 05, 2012 at 07:24 PM
Great suggestions all Colin.


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