Noooo Edinburgh, Don't Lift Ban on Changing Windows in Historic Structures
by Lloyd Alter, Toronto on 09. 4.08
Hill House, Scotland, Charles Rennie Mackintosh. Can you imagine this in vinyl?
John recently wrote that "Rising fuel costs and environmental concerns have forced councillors to consider lifting a ban on double glazed windows in Edinburgh's most historic buildings. Hundreds of residents in and around the New Town are currently prevented from replacing their draughty old windows, because of fears that double glazing would change the appearance of their properties."
Don't do it, Edinburgh! Donovan Rypkema lists a couple of reasons:
- The vast majority of heat loss in homes is through the attic or uninsulated walls, not windows.
- Adding just 3 1/2 inches of fiberglass insulation in the attic has three times the R factor impact as replacing a single pane window with no storm window with the most energy efficient window.
- Properly repaired historic windows have an R factor nearly indistinguishable from new, so-called, "weatherized" windows.
- Regardless of the manufacturers’ "lifetime warranties", thirty percent of the windows being replaced each year are less than 10 years old.
- One Indiana study showed that the payback period through energy savings by replacing historic wood windows is 400 years.
- These houses were built hundreds of years ago, meaning those windows were built from hardwood timber from old growth forests. Environmentalists go nuts about cutting trees in old growth forests, but what’s the difference? Destroying those windows represents the destruction of the same scarce resource.
Cheap windows in old Dublin building. Now the whole building looks fake. Discussion here
Rypkema also points out that sustainable development is about, but not only about, environmental sustainability.
1. Repairing and rebuilding the historic windows would have meant the dollars were spent locally instead of at a distant manufacturing plant. That’s economic sustainability, also part of sustainable development.
2. Maintaining the original fabric is maintaining the character of the historic neighborhood. That’s cultural sustainability, also part of sustainable development.
The character of so many houses has been lost because charlatan window salesmen promise 40% energy savings with replacement windows but it rarely comes close. Furthermore you can fix the windows and get magnetic storm windows that go on the inside, so that nobody can even tell the difference.
When the Rocky Mountain Institute analyzed the return on investment of different measures one can take to save energy, upgrading to high performance windows was one of the least cost-effective things on their list, costing $133.88 per ton of carbon saved, five times as much as weatherizing (caulking and sealing) the windows did. (PDF here)
A Vermont study showed much the same result, concluding:
Preservationists Take Heart
"Our study of old windows showed that the energy savings are similar for a variety of retrofit and replacement strategies. Rates of return on investment for energy improvements are quite low when starting with typical or tight windows with storms in place, but are significantly higher when renovating loose windows with no storm.
The difference in annual energy savings between renovating an old sash and replacing it with a new one was very small--retrofits saved only a few dollars.
For preservations, the good news is that with a proper choice of renovation strategy and good workmanship, historic sashes can be almost as energy-efficient as replacements. Window renovators and homeowners can give more weight to comfort, maintenance, lead abatement, egress requirements, durability, ease of operation--and historical value--without sacrificing energy savings. For those of us who work with old windows, this is very good news indeed."
Source: Creating Windows of Energy-Saving Opportunity by Andrew M. Shapiro and Brad James
The character of these houses will be lost; good windows thrown out for lousy ones; more energy will go into making the windows than will ever be saved through their lifetime.
If you have crappy sashless sliders that are rotting away, replace them. But historic Edinburgh? Forget it. ::Donovan Rypkema
Read more on window repair in TreeHugger:
Building the Green Modern Home: Looking at Windows
Donovan Rypkema : LEED stands for "Lunatic Environmentalists ...
Renovation Uses Twice As Much Labor, Half as Much Material as New ...
OK, there are two totally different things going on here.
First is heat loss through air exchange. This is why old windows really suck ass.
Second is thermal transfer through walls and roof.
Both are considered "low hanging fruit" when it comes to making an old home more efficient.
BUT, all the attic and wall insulation in the world don't mean a damn if all that saved heat just wafts out of drafty old crappy ass windows.
So yes, a perfectly restored old window that then has no drafts is very close to a new window. Care to figure out what it costs to hand restore all those ancient crappy ass single pane windows??? I thought not.
DUH!
With wooden-framed windows like what is undoubtedly in place in these old Scottish homes, it's relatively simple to modify part of the frame (known as the stop) to allow for double- or triple-pane sealed units to be installed. This does not involve switching out the sash or adding vinyl into the equation at all, and is a very common (and quite cost-effective) tactic in renovations. I can do it myself, and I'm no carpenter.
The add-on storm windows that you referenced in the post are inexpensive, but they do not protect the window against fogging between the panes, which is one of the major reasons that people replace their windows in the first place -- what's the point of a window you can't see through?
There certainly are more cost-effective ways of improving the insulation of a home than replacing the windows, but it's still something that CAN be improved. Praising a law that prevents people from doing so for the sake of appearances? That's disingenuous. Wind turbines and solar panels aren't very appealing to look at either, and many people find clotheslines distasteful, but those are all things that anybody with a green streak knows help out in their way.
Hmm. I'm not sure about the rest of this list, but the last point is spurious; clearly processed and used hardwood, that could be recycled into wood pellets for burning, is not the same resource as old-growth forests.
Also, having lived in historic Edinburgh buildings for years, I can tell you that they cost a fortune to heat, and that you can actually feel the heat escaping in the winter. The reality of this situation is unfortunately that the majority of these "historic" buildings are actually rented properties across the whole of the city centre, not New Town town houses occupied by affluent homeowners, and landlords don't want to make the investment in repairing OR replacing windows. So don't despair, this will probably have a very limited effect on the overall appearance of Edinburgh.
Yes, old windows can be restored and repaired and the cost of that isn't too different that the cost of a well designed and engineered window that matches the design of the original instead of a cheap replacement. As with many things, you get what you pay for. Plus, there is movement to train youth in traditional construction skills and this would appear to fall right into that thinking with a bit of coordination.
In the US is the National Registry of Historical Places and I know the UK has a similar list and being on such a list already dictates items like keeping the original appearances. So I would assume that the listed properties cannot buy any cheap replacement vinyl window and stuff it into the hole to stop drafts. This means getting more information and help that just the window sales rep.
Just like there are a variety of solar products that can be incorporated into a building without looking tacky [wind, thats a challenge], a variety of window products are available. You can't shop just at the home improvement store.
Other properties [the rentals] can find middle ground with an owner that cares. No amount of rules and legislation can change a tightwad into something else. But a few incentives from the local council or energy provider couldn't hurt.
We had our sash windows restored with draft strips added in and now they are perfectly sealed.
There is no point in fitting double glazing in these old buildings as they don't have insulated walls and so all the heat just gets absordbed out of the room anyway.
Ventilation is important in any building. Oversealing can cause sick building syndrome and mold buildiup, and can eventually damage the structure. An only partially-related example is the building where Canada's charter was signed (Charter House?). They covered the dirt cellar floor with poured concrete in the 50s, and the moisture retention over time seriously damaged the masonry. The concrete was removed a couple of years ago.
There are no real short cuts. If you seal up a building, be sure to dehumidify/ventilate.
Having lived in an Edinburgh new town flat exposed to the prevailing westerlies, I can confirm that it is an expensive and drafty experience. I also lived in Switzerland and Germany, where building regulations stipulate the replacement of old windows with energy efficient new ones even in historic buildings. These are usually hardwood frames with sealed double glazed panels.They replicate the EXACT appearance of the windows being replaced. So the technology is there: It should not be a problem to reproduce the exact appearance of traditional sash windows with double glazed replacements.