Window Improvement vs. Window Replacement

Most energy audit reports place windows very low on their list of energy improvement priorities. This isn't surprising because of the relatively high cost of replacement windows coupled with what are commonly marginal improvements in their thermal performance. Since audit reports generally prioritize energy efficiency improvement opportunities according to their cost vs. thermal benefit  (fuel savings) ratio, the energy payback economics of replacement windows are notoriously poor across the entire quality/cost spectrum of replacement windows. This is true because, in order to achieve significant thermal improvement with replacement windows one must invest in the very expensive triple-glazed units fitted with specialty glass and the fuel savings may not be recouped during the useful life of the window. 

While all of the above mentioned cost and performance factors may be true, I believe that the listing of windows as a low priority energy improvement opportunity is fundamentally flawed, often resulting in the audit doing an unintentional disservice to the building owner. This common flaw lies in the mistaken assumption that, aside from repair and weather-sealing, window 'replacement' is the only meaningful window improvement option. I want to encourage auditors to consider the merit of many other more affordable and cost-effective window improvement opportunities.

There is more to window performance than thermal efficiency, but this site is for energy professionals so I will focus most of this blog on thermal performance. Broadly speaking, there are three ways in which windows can be thermally improved: 1) repair and weather-sealing; 2) supplemental panels and window treatments; and, 3) window replacement. As we've all learned in Energy Efficiency 101, one should undertake (or recommend) the no-cost and low-cost improvements first; and, in the case of windows, the most bang-for-the-buck lies in Category 1: repair and weather-sealing. Many energy conscious building owners will have already accomplished this with caulking. Category 2: supplemental panels and window treatments are generally the next most cost-effective category of window improvement measures. These can include:  exterior storm sash, interior thermal shades, heavy curtains, and supplemental insulation panels. Of these options, exterior storms and thermal shades are most commonly found to be already in place, leaving supplemental insulation panels as a commonly overlooked but often quite affordable and highly cost-effective window improvement opportunity.

Obviously, there are those situations that demand window replacement for reasons other than thermal efficiency such as, structural integrity; but, if the existing windows are structurally sound, there are several cost effective ways to improve their performance, operation and appearance without resorting to replacement.

Future posts will address both optical and thermal window performance, as well as the human needs and expectations regarding window use, maintenance, operation and appearance.

Post Script:

After nearly 50 years as an architectural planning and design professional, an HVAC designer, an energy auditor and audit systems designer, a high-performance building consultant, and a residential general contractor, I narrowed my focus and sold high quality replacement windows in Northern New England for a year. This experience awakened me to the market's growing need for more affordable and cost-effective alternatives to window replacment. In response, two years ago I established Window Improvement Masters, LLC located in Orford, NH. www.windowimprovementmasters.com www.rjbacondesign.com

Though my current interests (and this blog) are focused on the role of windows in improving occupant comfort while achieving more efficient building performance; I recognize that all building systems - both static and dynamic, as well as human - must work together to satisfy the myriad needs of the building's owners and its occupants - and these needs go well beyond thermal efficiency and energy economics. I, therefore, welcome a discussion with others who appreciate the need for a holistic approach to addressing these inseparable matters of resource conservation and energy use in the built environment.

Views: 342

Comment

You need to be a member of Home Energy Pros to add comments!

Join Home Energy Pros

Comment by Bob Blanchette on July 14, 2013 at 5:04pm

I once had a house built in the 20's, the windows were the original wood ones, rot and all. I did TV repair at the time and used old screen protectors with weatherstripping as the additional pane. $5 for a roll of weatherstripping paid off is one month.

Comment by Robert D York Jr on July 7, 2013 at 8:01am

When I first started weatherization, back in the early 90's, window repair and weatherstripping was top priority. Auditors would have me rework the entire sash. Schlagel weatherstripping was used, glass replaced, new sash locks installed. Old windows became pretty much new. Talk to people about it in today's "weatherization" circles and they are clueless, or consider it to much work. Pay back on replacement may not get the SIR people are looking for, but, I'd be willing to bet that the old school approach to weatherstripping would. 

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy,) and brought to you in partnership with Home Energy magazine.

Latest Activity

Tom Conlon commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"I just checked the site Guidelines Kurt, and any true "promotions" should be posted in…"
3 hours ago
Tom Conlon posted a discussion

Whole House Fans - Love 'Em or Not?

I just searched this forum for "Whole House Fan", but I didn't find much about them (except …See More
4 hours ago
Richard Beyer replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Don, Thank you for the praise! I only wish that some of these profiteers could answer my questions…"
7 hours ago
Richard Beyer replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"Todd, This report (attached link) below on poor people living in subsidized housing show's…"
7 hours ago
Mike Kandel added 4 discussions to the group Building Performance Institute (BPI)
9 hours ago
Mike Kandel posted discussions
9 hours ago
Nate Adams commented on Jim Gunshinan's blog post My Energy Upgrade California—The Numbers Are In
"Jim, Glad to help! OK, a touch of soap box. So long as we don't tell people EE is free and…"
9 hours ago
Kurt Shafer commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Bob, Good idea. I see that you are a window energy reduction expert. You might consider adding…"
10 hours ago
Robert (Bob) Bacon commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Kurt, I would explain what energy/efficiency problem this device solves and explain the science the…"
10 hours ago
Ben Jacobs replied to Mike Kandel's discussion Our Homes Suck – And That's Why Our Kids Have Sinus Problems
"I agree that in many homes the indoor air sucks.  However, a lot of this problem is caused…"
12 hours ago
Kurt Shafer commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Tom, thank you for your odd reference to a leaky duck. It is a bit off topic since I was not asking…"
13 hours ago
Tom Delconte commented on Kurt Shafer's blog post What is your opinion about members promoting products here?
"Shameless self promotion here sucks like a leaky duck!"
14 hours ago

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service