The lifecycle analysis angle of the window replacement hype is massively overlooked, particularly for those homes that you mention with old-growth wood windows. Wood windows, when maintained & weather-stripped properly, have been proven to be just as airtight as new vinyl windows. The embodied carbon of a wood window is significantly less than that of its vinyl equivalent. The lifespan of those old wood windows? 4-8X longer, because they can actually be maintained. And at the end of their life, if that day comes, they can be recycled. Yet, replacement of older windows with new vinyl ones continues to be the go-to strategy of contractors and even government programs with no consideration for taking advantage of existing or replacement wood windows. Until all this is properly (and scientifically) accounted for in an evidence-based manner, of course preservation efforts look like the antithesis of sustainability. Our 120 year old home would receive thousands of dollars in incentives for replacing wood windows with vinyl versions. Yet no incentive is available for *restoring* existing windows or replacing with equally-performing and longer-lifespan wood versions. If you consider that even the greenest new-build home today will take 70+ years for its energy savings to offset the embodied carbon of its construction and manufacturing - and if windows are overall such a small part of energy savings as you point out - imagine the sad carbon payback period on all these vinyl windows and the opportunity cost of not addressing other high-impact areas first.
Interesting stuff, Lloyd, but I think you're damning all the author's suggestions en masse, rather than considering some of them individually.
Double-glazed windows don't have to be vinyl; there are plenty of craftsmen glaziers making very high-quality wooden double-glazed windows, even in traditional small-pane forms, which are almost indistinguishable from the originals. And yet, and this is where it gets really frustrating, in many conservation areas, such as the one in which I have my 1923-built, un-'listed', non-historic stone house, you aren't allowed to install such windows.
I have draught-proofed my house assiduously. I have double-insulated the loft. The shape and size of my rooms are such that internal dry-lining isn't practicable, but I've done my best with reassuringly expensive Wallrock thermal liner. However, I am denied one means (not the most effective, sure) of doing my bit with regard to windows. Frustrating.
I have friends who live nearby in a listed house from the early 1700s, the windows of which are streaming with moisture. The frames will rot and, as my friends don't have much money, that's another house which will likely go onto the 'under threat' list, while they fall ill.
It doesn't have to be like this. You're quite a cheerleader for Amsterdam, I believe, Lloyd. Quite right to. But that is a historic city in which large plate-glass windows are to be seen everywhere, even in houses which are hundreds of years old. I believe they are double-glazed. It's maybe not a historically accurate look, but it's a good look, in the same way that a wind-turbine in a lovely setting can be a good look: because you know it's sustainable, and because it's a sign that someone cares.
While you have a lot of good and factual points, you (and Orr whom you quote) are applying far too broad a brush. The reason many, if not most, people in the UK and old houses in Canada replace windows has nothing to do with energy savings: they do it because the comfort levels are terrible (the UK still has tons of single glazing) and/or the windows are at the end of durability cycle. As stated by another, no one said you have to replace the windows with vinyl, nor even that you need to use sealed IGUs (which will fail="wear out" in about 40 years). Just be prepared to pay a lot more. But improving the R-value to 4 or more is a huge benefit to comfort. And the draughts people feel are often cold air falling off of poorly insulated glazing, not air leaks, so you cant fix the comfort complaints by weatherstripping.
Yes, you are totally correct the storm windows are a partial solution, one that deserves a lot more attention, but many people dont want the hastle of removing them, giving up operability, condensation between panes etc. I think you need to understand what drives people to make the decisions, and not assume it is ignorance: in my experience, even when the facts you describe are explained, homeowners still look for affordable ways to get comfortable low maintenance windows. The life-cycle energy sales pitch is not that important and often false.
How you can tell from driving by a site that someone adding 1.5" of foam to their house has not already done all the airsealing they can and filled the attic with insulation is beyond me. Actually it is not: you can't tell you can only assume. Insulating walls when you are recladding (again, done for durabilty and style, not energy) is not a waste of money it is incredibly smart money, as this is the lowest cost time to upgrade for the next 50 years. Even if air sealing has not been attempted, I can do that from the interior at a later date, and I can always insulate the attic. When I decide to install new siding, this is the only sensible time to add the insulation. Exterior insulation definitely DOES make a difference, to comfort, to energy use, and even improves durability.
See my LinkedIn presentations on the building envelope options that include window additions. While the glass may only cause 10% of the heat loss there are many windows with air leakage and thermal bridging that cause more than 10%. Each building and project is different and needs to do the feasibility study using RetScreen or other tools that have the energy usage of the building appropriately identified so that the areas of improvement can be evaluated for costs and benefits. Many of our window insert projects are for noise reduction as well as energy and for comfort of the occupants sitting near the windows!
Probably interior storm window inserts, fixed storms and exterior storms may also be an option for you. There are plastic inserts which will suction fit to the inside of your window and improve performance as well, but they can trap moisture and cause rot issues, so aren't as good as a long term solution.
I’m really enjoying your more “unedited” writing, I hope you keep at it 🙂
The lifecycle analysis angle of the window replacement hype is massively overlooked, particularly for those homes that you mention with old-growth wood windows. Wood windows, when maintained & weather-stripped properly, have been proven to be just as airtight as new vinyl windows. The embodied carbon of a wood window is significantly less than that of its vinyl equivalent. The lifespan of those old wood windows? 4-8X longer, because they can actually be maintained. And at the end of their life, if that day comes, they can be recycled. Yet, replacement of older windows with new vinyl ones continues to be the go-to strategy of contractors and even government programs with no consideration for taking advantage of existing or replacement wood windows. Until all this is properly (and scientifically) accounted for in an evidence-based manner, of course preservation efforts look like the antithesis of sustainability. Our 120 year old home would receive thousands of dollars in incentives for replacing wood windows with vinyl versions. Yet no incentive is available for *restoring* existing windows or replacing with equally-performing and longer-lifespan wood versions. If you consider that even the greenest new-build home today will take 70+ years for its energy savings to offset the embodied carbon of its construction and manufacturing - and if windows are overall such a small part of energy savings as you point out - imagine the sad carbon payback period on all these vinyl windows and the opportunity cost of not addressing other high-impact areas first.
Welcome back professor to the housing world you love; treehuggers loss..
Interesting stuff, Lloyd, but I think you're damning all the author's suggestions en masse, rather than considering some of them individually.
Double-glazed windows don't have to be vinyl; there are plenty of craftsmen glaziers making very high-quality wooden double-glazed windows, even in traditional small-pane forms, which are almost indistinguishable from the originals. And yet, and this is where it gets really frustrating, in many conservation areas, such as the one in which I have my 1923-built, un-'listed', non-historic stone house, you aren't allowed to install such windows.
I have draught-proofed my house assiduously. I have double-insulated the loft. The shape and size of my rooms are such that internal dry-lining isn't practicable, but I've done my best with reassuringly expensive Wallrock thermal liner. However, I am denied one means (not the most effective, sure) of doing my bit with regard to windows. Frustrating.
I have friends who live nearby in a listed house from the early 1700s, the windows of which are streaming with moisture. The frames will rot and, as my friends don't have much money, that's another house which will likely go onto the 'under threat' list, while they fall ill.
It doesn't have to be like this. You're quite a cheerleader for Amsterdam, I believe, Lloyd. Quite right to. But that is a historic city in which large plate-glass windows are to be seen everywhere, even in houses which are hundreds of years old. I believe they are double-glazed. It's maybe not a historically accurate look, but it's a good look, in the same way that a wind-turbine in a lovely setting can be a good look: because you know it's sustainable, and because it's a sign that someone cares.
While you have a lot of good and factual points, you (and Orr whom you quote) are applying far too broad a brush. The reason many, if not most, people in the UK and old houses in Canada replace windows has nothing to do with energy savings: they do it because the comfort levels are terrible (the UK still has tons of single glazing) and/or the windows are at the end of durability cycle. As stated by another, no one said you have to replace the windows with vinyl, nor even that you need to use sealed IGUs (which will fail="wear out" in about 40 years). Just be prepared to pay a lot more. But improving the R-value to 4 or more is a huge benefit to comfort. And the draughts people feel are often cold air falling off of poorly insulated glazing, not air leaks, so you cant fix the comfort complaints by weatherstripping.
Yes, you are totally correct the storm windows are a partial solution, one that deserves a lot more attention, but many people dont want the hastle of removing them, giving up operability, condensation between panes etc. I think you need to understand what drives people to make the decisions, and not assume it is ignorance: in my experience, even when the facts you describe are explained, homeowners still look for affordable ways to get comfortable low maintenance windows. The life-cycle energy sales pitch is not that important and often false.
How you can tell from driving by a site that someone adding 1.5" of foam to their house has not already done all the airsealing they can and filled the attic with insulation is beyond me. Actually it is not: you can't tell you can only assume. Insulating walls when you are recladding (again, done for durabilty and style, not energy) is not a waste of money it is incredibly smart money, as this is the lowest cost time to upgrade for the next 50 years. Even if air sealing has not been attempted, I can do that from the interior at a later date, and I can always insulate the attic. When I decide to install new siding, this is the only sensible time to add the insulation. Exterior insulation definitely DOES make a difference, to comfort, to energy use, and even improves durability.
See my LinkedIn presentations on the building envelope options that include window additions. While the glass may only cause 10% of the heat loss there are many windows with air leakage and thermal bridging that cause more than 10%. Each building and project is different and needs to do the feasibility study using RetScreen or other tools that have the energy usage of the building appropriately identified so that the areas of improvement can be evaluated for costs and benefits. Many of our window insert projects are for noise reduction as well as energy and for comfort of the occupants sitting near the windows!
100% in agreement with you Lloyd.
Can you clarify what you mean by window "inserts"? Asking as the owner of a 100+ year-old house in Ottawa, with a few original windows left.
I have Indow inserts on my own home, more info: https://www.treehugger.com/save-your-windows-and-your-money-indow-window-inserts-4858724
Probably interior storm window inserts, fixed storms and exterior storms may also be an option for you. There are plastic inserts which will suction fit to the inside of your window and improve performance as well, but they can trap moisture and cause rot issues, so aren't as good as a long term solution.