Mailbag: Wood Windows and Energy Efficiency
Here was the email that I received this afternoon from Zach:
Hi,
I noticed from your blog that you're removing your old windows and taking them to the "stripper." I have been contemplating a renovation project on our own 3-flat and we have been discussing whether to replace our old windows or not. I'd like the renovation to be as "green" as possible both in terms of the process and the products used. A major part of this is making the home more energy efficient. If the windows allow lots of air to leak, then we're not really going to accomplish our goal. I'd love to keep them if there was a way to make them more efficient. So, is this something you guys pondered at all? Did you come to any conclusions about how to make older windows "not so drafty?"
Thanks so much and keep up the great work on your website. It's a great read.
Zach
Zach, thanks. Though I think "great read" is a bit too positive. I think following our blog is like watching a car wreck in slow motion. It horrifies you, but you can't seem to turn away. Anyway.
I want to acknowledge that the windows debate can be a flash point among old house owners. And I don't want to insult anyone else's choices. We all have different priorities and I can only talk about why I'm doing what I'm doing. Plus, this answer is going to be LONG. I'll try to make the explanation simple, but I want to be clear. So, I'm going to spread it out over a few days. And, you know. I'm lonely. I want you to come back more than once, you know?
I wish I could say that I am undertaking this windows restoration project because I am noble and eco-friendly. The truth is that I am picky about aesthetics, stubborn and short on cash. Let me explain.
Given the choice of spending loads of money (if I had it) on perfect and aesthetically NEW windows (triple glazed and low-e gorgeousness with true wood muntins dividing the lights) OR flailing away in my basement slashing my wrists with a glazing knife while refinishing old windows, I would choose the former. There. I said it. Old house purists, you may now commence hating me.
When we were trying to decide what to do with the windows, Aaron graciously deferred to my judgment since I was so passionate about them. I researched energy efficiency and our choices. Here is what I found.
There are two types of heat loss related to windows: infiltration and thermal loss. Let's oversimplify. When you sit in front of a window during the winter and feel a breeze on the back of your neck? That's from infiltration. When you put the palm of your hand directly on the glass and it is freezing cold? That's thermal loss.
In examining our old wood windows, I tried to determine what kind of heat loss I was dealing with. The infiltration was quite obvious. I found it in a number of places. Let's take a look at some photos of a wood window so I can communicate in technical terms:
This is a sash. It is made up of lights (those pieces of glass) which are divided by muntins. This is why it is called a divided light window.
This is me, two weeks before I gave birth in 2006, prepping a window jamb. Because our window is double-hung, two sash(es) fit into each jamb. This is different from the fact that I completely jam because I was attempting this while nine months pregnant. On either side of the jamb are the pulleys.
The two sashes in my window are hung in the jamb by chains. (Other types of windows use rope.) The chains are attached to the sash on one end and the window weights on the other end. They move up and down courtesy of the pulleys. (See previous photo.) The sashes are separated from each other by a long piece of wood called the parting stop. This stop keeps the windows from clanging into each other.
So, where are the weights? On either side of each window, in a big empty space behind the trim.
Okay, now go look closely at your own old wood windows and see if you can find all of these parts. Go ahead. I'll wait.
To be continued...
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Comments
I too have a soft spot for the original windows. Most of it is because I find the old wavy glass beautiful. It's not an easy decision, but I love the way your windows look. The divided lights are gorgeous!
Posted by: Trissa | August 1, 2007 9:38 AM
I've done my homework and am awaiting the 2nd installment. I need help knowing how to get the trim board that goes around the window (to expose the sash weights)off. Would you please include this in the explanation whenever appropriate.
Posted by: Meggan | August 1, 2007 9:38 AM
I am one of those old house purists regarding windows. But one of the reasons I would keep the old, even if I could handle spending loads of money on perfect new windows is the fact that the old are made from old growth wood, which wears like iron. Perfect new windows would never be made from old growth lumber, and will never last as long. (Which would be pretty much forever.)
Posted by: deb oconnor | August 1, 2007 10:33 AM
I am one of those old house purists regarding windows. But one of the reasons I would keep the old, even if I could handle spending loads of money on perfect new windows is the fact that the old are made from old growth wood, which wears like iron. Perfect new windows would never be made from old growth lumber, and will never last as long. (Which would be pretty much forever.)
Posted by: deb oconnor | August 1, 2007 10:34 AM
hope I am not stepping on your toes if I suggest doing a google search to Megan on "replacing sash cords" the DIY dr. shows a great visual of how dble hung windows are put together and the weight cover that allows you to replace the cord without removing any trim. the problem is usually that this panel is painted over or has weatherstripping attached to it that it's hard to get open. And loving this post, I too am a purist trying to salvage my original windows, so am looking forward to your tips on making this as efficient as possible.
Posted by: ejk | August 1, 2007 10:57 AM
You know, maybe there is something to be said for the older windows, dating from the first half of the 20th century. I lived in a home built in 1927 with all of its original windows (double-hung) and never had a problem, except maybe a broken rope every now and then. And, when the original wood storms were up they were pretty darn energy efficient, as well...very little heat loss.
Well, now I live in a 1958 ranch-style home which also has all of its original casement and awning style windows. To put it bluntly, I hate these windows!!! They seriously have to be the most inefficient windows ever, and I'm not exaggerating. I've tried everything to make them better. Nothing has worked.
Anyway, maybe it's just that they were cheap to begin with, or they were poorly maintained over the years by previous owners. Perhaps it's the style of window (casement/awning vs. double-hung). Who knows. All I do know is I'm counting down the days until I can afford new windows.
Posted by: Chris | August 1, 2007 12:46 PM
Yippee! I'm so excited for your new window posts. I'm looking forward to the next installment. We will be working on our windows next spring, so I'm hoping to learn lots from you. I already got "Working Windows" from the library to get going - something you mentioned in an earlier post. Oh, and love the photos - makes reading your detailed blog that much easier!
Andrea
Posted by: Andrea | August 1, 2007 2:21 PM
Trissa - Hey! Good to see you! Thanks...I love my divided lights :)
Meggan -- I'll try to write about the access panel, although I don't have a ton of experience with it since I always go behind the trim.
deb, ejk, chris - I'm obviously an old windows fan too. And absolutely, that old growth wood is fierce and there isn't anything like it. Love that you all are on. (And there is no stepping on toes! I'm an amateur and could use any input you've got.)
Andrea - Yeah! Working Windows is excellent. I really loved that book.
Posted by: jm | August 1, 2007 10:07 PM
There's nothing like the look and beautiful wood of original windows. The quality is so much better than the 1950s and 1960s aluminum-framed junk in the house where I grew up.
We are in the process of stripping and refinishing our original wood storm windows and screens (and later the windows themselves) on our 1923 Chicago bungalow. We've gotten to love the infrared stripper (http://www.silentpaintremover.com/).
Got a long way to go yet, but what we've done has turned out well. Of course, when we get to popping off the trim, opening the pockets and replacing the ancient weight cords (after cutting the paint on windows that have been painted shut for years), I'm guessing we'll be cursing that phase of the project a bit more.
Posted by: Anne Alt | August 4, 2007 7:42 AM
Meggan: Congratulations on undertaking this project to save your original wood windows. In your pictures I see your windows have a weather stripping called interlocking. It fits in slots on 3 sides of the sash and has another interlocking piece at the meeting rail. This is a high end weather strip solution but is very tricky to install. If it is in good condition and properly installed, it is a very good system. I have restored and weatherstripped hundreds of windows for my customers and all have been glad they restored rather than replaced with some shiny white plastic or even high end wood windows. I look forward to following your progress.
Posted by: Dave B | September 9, 2007 8:04 PM
Could David B Sept 9, 2007 tell me where I could find someone in Chicago who could restore and wheaterstrip our old windows. THEY ARE 1911 ERA What type of storms would you suggest?
Posted by: Barbara B | October 28, 2007 9:50 AM
I can make windows for you guys- I've been doing this for a few years now, replacing the entire structure with a dead on replication of the originals with a few improvements- concealed weatherstripping, sealed weight channels, etc. I couldn't find anything that matched my bungalow so I bought machinery and refined the process of what was done a century ago. If you'd like, check out the Driehaus awards for 2005 on chicagobungalow.org under small scale project. There you'll see my dining room set. The only original parts were the weights, everything else replaced. I'm completing a 1940's English Tudor near Superdawg, so I'm taking orders! If interested, email me at darrenurbs@yahoo.com. I can send more pictures but I don't yet have a website. I'm in Norwood Park (Chicago).
Posted by: Darren U. | March 4, 2008 7:57 PM
Has anyone heard of ways to double-glaze existing windows?
I just came across something that is available in the UK, and would love to know if there is a similar product here:
http://www.sashglass.co.uk/
I've tried to think of anything to search on, and haven't found any products, or diy approaches.
Posted by: Scott | July 14, 2008 4:00 PM