Tuesday, September 23, 2008

Dealing With Windows- The Energy Efficiency Edition

The windows on our house are in need of SOMETHING to make them more energy efficient. But what? There are so many options...

Here's a picture of one of the worst offenses...

You can see that the parting bead is cracked, and the glazing is in less than desired (virtually non-existent) condition.

Replacement Windows- VINYL

There is lots of information out there about how wonderful vinyl replacement windows are. Unfortunately, most of it is from the vinyl window trade. (I have yet to find an independent study). I am not convinced.

For starters, vinyl windows have an industry stated life of 10 to 15 years... 2 years before the special Argon gas escapes and you are left with air, 10 years before moisture makes its way into the space and starts to fog the window. My wood windows have lasted for 100 years... and I would expect nothing less of any other window.

Second, vinyl windows are full of lead. The lead plus other chemicals off-gassing into the house can't be good. I will take my lead painted windows, carefully encapsulated in fresh paint or safely stripped of all lead paint, over a window that will release lead no matter what.

Third, the manufacturing process for vinyl windows can't be environmentally friendly, and the energy required to make them is certainly more than I will expend restoring old windows.

More information:
Blue Vinyl is a wonderful documentary about vinyl siding and its effects on people and the environment. Most of the information applies directly to windows. It's worth a look.

Jeanie at House in Progress has created a fabulous essay on the (de)merits of vinyl windows. There quite a lot of interesting information there. Be sure to click on the links and read the tables/charts.

Replacement Windows- WOOD

Replacement wood windows sound like a comparable option to your existing wood windows. However...

Newly harvested wood is not comparable to old wood. New wood is from quick growth forests and farmed trees... harvest young after only 30 years or so. It is much less dense than old growth wood, and rots/dents/breaks much easier. I have heard of new wood windows rotting out in 15 years. Also, the softer wood does not provide the same level of insulation as heavy, dense wood does from wind.

Wood windows are also much more expensive, are often clad with vinyl or have vinyl tracks, and still require a significant amount of energy to create. (Plus, your old windows end up in the landfill).

New wood windows are the best option, however, if it comes to replacement.... as long as you pick woods like cedar and mahogany, and make sure there is no vinyl or aluminum cladding or sliders.

This leaves us with restoration. Your 100 year old wood windows have lasted this long; properly restored, they will last another 100 years or more. Restoration also keeps wood and glass out of the landfill.

By simply adding a properly fitted storm window to a properly functioning single paned, double hung window, you will increase the r value by more than 2, and bring it up to the r value of all but the beefiest replacement windows. Adding drapes or blinds will decrease this difference.

Our plan is to reglaze our windows and make sure they are working properly. They have aluminum triple track storms right now... eventually I want to make period appropriate storms out of wood instead. I hope to be able to compare our new wood/aluminum clad double paned Pella window with our original windows for some real life data... I promise to share it no matter how it turns out.

I'll leave the nitty gritty details on window restoration as I figure them out... stay tuned!

The Numbers
In the September, 2007, issue of Old House Journal there are some numbers crunched on monetary savings. I will leave you with them.

Estimates made with 3'x5' window; gas heat @ $1.09/therm.

Single-pane Original Wood Window with Storm Window
Cost for storm = $50*
Annual energy savings = 722,218Btu
Annual savings per window = $13.20
Simple payback = 4.5 years
*This cost is way too low for most storms. The numbers still work out in the favor of this option with a cost of $150 per storm, however

Double-Pane Thermal Replacement of Single Pane Window (No Storm)
Cost $450.00
Annual Energy savings = 625,922 Btu
Annual Savings per window = $11.07
Simple payback = 40.5 years

Double-Pane Thermal Replacement (Low E Glass) of Single-Pane Window (No Storm)
Cost = $550.00
Annual Energy Savings = 902,722 Btu
Annual Savings per window = $16.10
Simple payback = 34 years

Double-Pane Thermal Replacement (Low E Glass) of Single-Pane Window WITH Storm
Cost = $550.00
Annual Energy Savings = 132,407 Btu
Annual Savings per window = $2.29
Simple payback = 240 years

Source: http://www.oldhouseweb.com/forums/viewtopic.php?f=2&t=14583&st=0&sk=t&sd=a&hilit=window+ratings


Jenni said...

GREAT post!

Anonymous said...

Another blog came to similar conclusion - but without the supporting data. All the engineers in house blog land are loving you.

She pointed out that the replacement window people often compare original wood windows to replacement windows - and forget to mention that original wood windows were meant to have screens & storms - so winter heat loss was not as great as what they quoted because you should be putting storm windows on.

Good luck restoring and getting new storms for your windows. It is going to be lovely!

Cheryl in Orlando

Muskego Jeff said...

"The lead plus other chemicals off-gassing into the house can't be good."

Off gassing is typically found in vinyl or PVC products which are made with plasticizers, such as vinyl shower curtains. Most people have opened a new shower curtain and gotten a strong whiff of what I'm talking about. And no, it's not good to do that, no matter how great it smells!

However PVC products made WITHOUT plasticizers are now being considered "neutral", and neither harm nor help air quality.

I work for a manufacturing company which makes PVC/vinyl products for use specifically in hospitals and nursing homes, and all testing by the various Green agencies now point to products without the plasticizers as being safe.

I would assume that the vinyl covered windows do not have any plasticizers in them, as the plasticizers mainly are used to make the material flexible (like a shower curtain). Rigid material doesn't need it.

With all that said, I have two opinions on this topic. First: it's one window with a minimal amount of vinyl. The impact on the environment is minimal - plant a few trees to even the score and don't feel guilty. Second: re-do your wood window if that's the style in the rest of the house. I think nothing looks sillier than a nice old house stuck with windows that don't match the style of the house. Take it apart, clean it up, new glass & glazing as needed, and a coat of paint. That's what I'm planning for next year on my own house at least.

Anonymous said...

Hi Kiddos!
From personal experience don't go with removeable storm windows. When it comes to cleaning them you're doubling your work.

When we replaced our old double storms with vinyl double panes 8 years ago--as far as cleaning, they were a god-send. However, within three years, two sliders and three large fixed panes had broken their seals. The removable screens have little tabs to pull the screens out for cleaning--half the tabs pulled out by the second year. The vinyl on the hottest side of the house is yellowing and virtually all the vinyl has a powdery residue covering the outside. Finally, they're not good for cutting the street noise--the old aluminum storms did better than these.

All and all we should have gone with a higher quality window. Unfortually, we got what we could afford and that turned out to be crap.

We looked at Pella and Anderson-- very $$$. All and all, they may have been worth it. I'm not recommending "P" or "A", but glad you're doing your research!!

Much Love
Ant Barb

Jayne said...

"I think nothing looks sillier than a nice old house stuck with windows that don't match the style of the house."--Muskego Jeff

Well said, Jeff, and I agree completely. My advice would be to restore your original windows and add storms if they're not already present. "The Old-House Journal" had an article a few years ago--which I can't locate at the moment--proving that original windows, repaired and reglazed if necessary, with tight-fitting storms are nearly as energy efficient as new windows. And they look better, in my opinion.

Robj98168 said...

I must diasagree with you about the vinyl windows. I moved into theis house about 9 years ago, and the windows here were put in about 3 years before- and I have never had a moisture problem. I do agree though in a home like yours that wood would be better looking. One thing I did, too was buy some of my windows from 2nd Use, a local salvage that supports Habitat for Humanity (Replacement windows for garage) I also donated my old windows we took out for the addition to them, as well as entry doors. I just added my new window to the kitchen. Looks grat and the light coming in is fantastic,now I gotta keep sammy, my cat out of the window (or rather of the counter!)

NV said...

Great info! Windows are probably the one BIG thing we HAVEN'T done when it comes to energy efficiency. And it's the expense that's the roadblock.

for now, caulk and patch, paint. Repeat.

Karen Anne said...

muskego jeff,

What about the "plastic" stuff used for tvs or some notebooks or small electrical products like emergency lights?

That so often comes with a brain-frying chemical smell to it, that I no longer let it in the house, it just can't be good.

It seems to be distinguished from other plastic by being just slightly soft to the touch.

A refugee from a checmical company told me it was "probably a residual of
the "polycarbonate" material used in the injection mold process used to make
the plastic fans (or plastic anything)."

It never stops smelling like this, no matter what the manufacturers say.

Josh said...

Your efficiency and cost/benefit figures-- as well as the stated life expectancy of replacement windows-- are consistent with what I've read elsewhere from people who weren't trying to sell me windows or the labor to install them. And your compelling financial calculations don't take into account that in many markets, well-maintained original windows contribute more to home equity than consumer-grade replacements. Bottom line: replacement costs, but preservation pays.

Muskego Jeff said...

"What about the "plastic" stuff used for tvs or some notebooks or small electrical products like emergency lights?"

Got me on that one. I'd guess that it depends on what company made it and what their "formula" was for the material. PVC, PETG, ABS, etc. all have their own formula, and some probably smell more than others. I don't doubt that a lot of the plastic and PVC we get now is from China. All bets are off as to what they're using.

My take on it is that if you don't like the smell, don't buy the product. My house is far from air-tight so I'm not worried about the minimal off-gassing that may be going on here.

Jennifer said...

Muskego Jeff~ I really should have (and meant to have) added a note about this being for OLDER houses (say pre 1950) that have old wood windows. There is definitely a great deal of style element involved in windows!
There is still lots of flexible vinyl in the vinyl windows I've seen (though I have only seen the cheap ones up close)... in the weatherstripping and channels and such. It's not as much as the whole window... and HONESTLY not as much as my VINYL shower curtain :) (which I bought 5 years ago before I started caring about such things).

Ant Barb~ Sorry you had such problems with the windows! The window we just installed is a Pella window, so hopefully it will hold up...

Rob~ Glad you donated your old windows! We've done that, too, with some of the windows we have removed from INTERIOR walls. We'll have to agree to disagree on windows.. see my Ant Barb's comment above on HER vinyl window experience (which I didn't know she'd had until now!).

pedalpower said...


I wish our house still had the original storm windows...someone threw them out and covered our windows with triple track storms. I hate the way they look and the pain in the butt they are to clean. But we are keeping our old wood windows here too.

In our area the big thing is to replace your windows with new ones...everyone brags on the few dollars they save every month...they seem to not realize that by they time those savings pay for the windows, they will need more new ones. More money than sense out there I think.

A. said...

Wonderful post. I've argued this to lots of people, but you've really done your research - I'm going to refer them over to you!

S and N said...

Thanks for the great post. Restoration is a truly worthwhile endeavour, but be prepared for a huge investment of time. Before painting our house this year we dug out the worst of the old, cracked window putty and reputtied the windows with linseed based window putty(over 14 original storm windows and several inner windows in total). There is a kind of pleasure in window puttying--it's very tactile and rewarding when you start to get it right. Although nothing beats the original wood windows, we are putting in some good quality double hung wood replacements in some of our renovated rooms as we go. We used a company called Lepage Millwork from Quebec, Canada. The prospect of lugging the very heavy wooden storms up the ladder to the second story every fall and back down in the spring was the main thing that stopped us from keeping all the windows original.

C&C said...

Wow, that was a lot of research! Good luck restoring your windows, I think that will turn out very nicely. I can't wait to see how they turn out!

Just A Girl And Her Craftsman said...

I have the same issue on a few of my windows and I just wanted to thank you for this post. There are two vinyl replacement windows in my house and the rest are original-- I absolutely hate the vinyl windows but they are the only ones that open, shut and lock properly. The windows are on my list of things to do but for now I'm stripping wood in the living room and dreaming of the day I can remove the wood paneling.

min hus said...

Great post. I have also chosen to repair my old wood windows, although I couldn't afford to replace them even if I wanted to. :)

Luckily my house came with storm windows for everything. But restoring my old windows is a LOT of work. I did three last year and haven't managed to work up the motivation to tackle the other nine this year. But those three windows I did get done? They sure do look nice. :)

Green Fairy said...

A lot of terrific information. The only original windows I have left in my house are the basement ones, and we're trying to figure out if we should restore or replace them. Right now, they're leaking cold air like crazy. But none of the modern options are satisfying.

The previous owners had installed vinyl windows on the upper levels prior to our buying the house, but so far I'm not impressed. They're only three years old (I think), but look a little weather beaten already.

Why S? said...

Excellent information. I finished replacing all my windows this year, with wood framed Pellas. I'm sure there is some kind of vinyl in the tracks. But I have to say I love them (yes, they were pricey but we bit the bullet.) This summer, the house was so much cooler than in past summers and I'm sure it's because of the new windows and insulation. Which means, we won't need to install A/C.

Why S? said...

and Muskego Jeff, I just want to say that whiff of vinyl - always makes me think of Christmas. Sad, huh?

Why S? said...

I have to add that I did NOT replace original windows. I replaced crappy aluminum and louvered windows. There were no originals left by the time we got here.

LisaZ said...

My husband has followed This Old House directions and completely redone all the windows in all three of our old houses. He is just finishing up with the many, many old windows in our current home. We've been here four years and he has spent every summer doing a few at a time. The investment in time is paid off manyfold with beautiful windows that now function properly, look great, and are certainly sturdier and more weather proof than any type of new windows.

We installed a couple vinyl windows in our last (much more hopeless) house and we hated them. They were nowhere near air-tight and with your stats on how long they last I will not be surprised if the new owner has to replace them in a few years.

Also in that house we put in some nicer Pella wood and steel windows which were much, much better. The old windows in that house were really really terrible so they got replaced.

The windows in our current house also LOOKED terrible with little or no glazing, terribly peeling paint, etc, but they were still worth re-glazing and painting. Now, as I said, they are gorgeous and without much money spent!

We have also gone with high quality white coated metal storm windows for this house instead of replacing the aluminum with wood. Because our trim is white they look great and work so easily.

Anonymous said...

I'd like to clarify a few items regarding this blog.

PVC does not off-gass lead.
They do off-gass other chemicals.

PVC always has plasticizers. Different varieties have differnt proportions of them to acheive the desired properties.

PVC windows, while cheap, come at a cost for someone somewhere. Blue Vinyl clearly pointed that out in Louisiana's Cancer Alley.

The energy calculations are problematic in that the dbl paned low E with storm windows only saves $16/year, but without the storm windows saves nearly 10x. Something is wrong here.

Patrick Hayes, the guy in Blue Vinyl who remodeled the house.