Glass Fails In The Near Future

After 20 years, another 10 to 15 percent of thermal windows will fail as they are exposed to the elements. And by the 25 year mark a growing number of cladding systems will have major thermal failures, requiring the building skin and/or its mechanical systems to be upgraded entirely.

What are the real costs facing owners of glass condos? (By Lloyd Alter) -  There is much to complain about glass condos; we have noted that they are costly to heat and cool, often uncomfortable and hard on the furniture. As John Straube has noted, "Glass and aluminium are great for cookware but not for buildings." What we haven't noted is the inevitable cost of replacement. In Canadian Facility Management and Design magazine, one of those dead tree trade publications I get sent as an architect, quantity surveyor Joe Pendlebury describes the problem of the glass wall. He claims that five percent of thermal windows may have failed even before they are delivered to the job site.

After 20 years, another 10 to 15 percent of thermal windows will fail as they are exposed to the elements. And by the 25 year mark a growing number of cladding systems will have major thermal failures, requiring the building skin and/or its mechanical systems to be upgraded entirely.

And he is talking about commercial buildings here, not just the window wall systems used on condos. Thanks to the different rates of expansion between aluminium and glass, over the years the seals break down between the framing and the glass, the argon gets out of the sealed units and moisture gets in. Pretty soon the whole system has to be replaced.

The costs of replacing entire walls of glass are prohibitive to some owners of high-rise structures. The average cost to remove and replace a cladding system from a swing stage is about $200 per square foot. As the typical floor-area-to-cladding ratio in high-rise structures is .33, this will translate into a cost of $66 per square foot over the above grade areas of a typical building.

And that doesn't include the cost of the interior finishes, where drywall might have to be busted to expose the anchoring systems, ceilings, and possible relocation of occupants while the work is being done. The owner of a 700 Square foot unit might get hit with an assessment of close to $50,000 if there isn't a big reserve fund to cover it.

Fortunately the building codes are changing and the all glass buildings are no longer the standard. However there are a whole lot of them out there now that are going to have to be fixed in the rapidly approaching future, and it is going to cost serious money.

Glass and aluminium have very different coefficients of expansion, and the sealants are exposed to sun, wind and rain for years.

Why Architects Shouldn't Build Condos out of Glass And People Shouldn't Buy Them: Glass balcony panels are raining down on the streets of Toronto from the shiny new condominiums, building envelope expert John Straube was interviewed on Ontario Morning to discuss the problem. He didn't say a whole lot about why the panels are falling, but did a great explanation of the problems that come from building condos out of glass. There is a big difference between the glass on office buildings and on condos; the former is usually curtain wall, that runs continuously on the exterior, the latter is window wall, really a modified store-front wall redesigned for condos, supported by each floor and running from slab to slab. It is a lot cheaper.

• Glass and aluminium are great for cookware but not for buildings.
• With floor to ceiling glass, you have nowhere to hang a picture, place your furniture or change your underwear.
• Energy efficiency is five times lower than a conventional wood framed house.
• The glass area is so large that it is difficult to control temperature, it's too hot or too cold.
• If we care about the long term, we should go for a balance, no more than 30 or 40 percent glass.

Straube noted that while aluminium and glass are easy to clean and durable, the sealants and gaskets are not, and will need maintenance and replacement down the road. This is not cheap or easy, and the burden falls on the condominium association and the owners. (Glass and aluminium have very different coefficients of expansion, and the sealants are exposed to sun, wind and rain for years.)

Straube suggests that the reason architects choose to build like this is about style and not cost, but I disagree, having worked with the architect and window manufacturer for the project with the falling glass (which was from the balconies, not the windows, and from a different manufacturer) on some of the earliest all-glass projects in Toronto in the 90s. It's a lot cheaper and a lot easier for a developer to work with one trade, the window wall supplier, than to coordinate among trades when mixing precast or brick with glass.

The building code encourages it too, by regulating the R-value of wall constructions, like saying all solid walls have to have an R-Value of R20, but not regulating the overall heat loss through a wall, so a builder can put up a glass tower with an R Value of R4 and comply with the code.

If the authorities in Ontario said, for example, that a total wall area must have an average R-value of 10, then designers would have to figure out a mix of solid wall and glass, and if they wanted more glass they would need to buy better windows, and stop building radiator fin balconies.

But that would raise costs and prices and might kill the golden goose that is the Canadian condo boom, so they will just let the condo purchasers worry about it a decade from now.

Prof. Kesik, projecting 10 years into the future when he estimates their glass walls will fail prematurely.

Glass Towers May Be Sexy, But They Need To Put A Coat On: Ted Kesik doesn't mince words. When everybody else was gaga over Jeanne Gang's Aqua he described it: Take your clothes off, attach a series of highly conductive fins, like the kind they put on motorcycle engines, to the skeleton of your body, and go stand outside in January... Then tell the person who is dressed for winter they are boring, overly practical people who are squashing creative expression.

Now he is back with more architectural pornography imagery, discussing Toronto's new condos and their very thin glass walls with Dave LeBlanc of the Globe and Mail: As a building scientist, I look at buildings the way a doctor looks at a body: I say ‘Ah, it may look sexy but boy, that’s not very healthy. I don’t know if I’d want to be that thin.”

When he is not complaining about new glass buildings, he is helping to fix older ones as part of Toronto's Tower Renewal Project. The towers built in the sixties are solid and had real walls with punched windows, so that they can be retrofitted by adding an exterior insulation and finish system. He calls the old buildings "tough, rugged and robust".

The same cannot be said for our new glass towers. Dave LeBlanc quotes Kesik in the Globe And Mail - “That’s not what’s going to happen to all those wonderful buildings down at Concord Place,” snarls Prof. Kesik, projecting 10 years into the future when he estimates their glass walls will fail prematurely. “They’re going to have to evacuate.” So why do young people line up to purchase there despite the fact that energy performance is usually as bad as a 1960s or 70s building before tower renewal? It’s either the media portraying them as “sexy” or, more likely, that buyers just aren’t aware of their failings: “No industry that I know of provides so little factual information to the consumers of its product; you look at every other industry and they have to convey technological advances or they don’t get sales.”

Failed Windows, Seal Fail & Window Walls

Throw-away Buildings & Thermal Window Failure: How it Happens: Virtually all glass condominium towers feature window wall systems (floor-to-ceiling walls of glass) enclosing the entire facade. Window walls yield spectacular views, but owners who buy a condo unit for the view may not realize that they're relying on a couple of panes of glass separated by less than an inch of insulated space to protect them from the elements. That insulated barrier will degrade over time, even as energy costs increase. On some buildings, five per cent of the thermal windows may have failed before they're even delivered to the construction site. Another 10 - 15 per cent will fail by the 20-year mark as they're exposed to the physics of heat expansion. By the 25 year-mark, a growing number will fail every year. Here's how it happens:

Insulating gas is sealed between glass panes: Insulated glazing technology, commonly known as double glazing, considerably improves the thermal efficiency of the window units used on older buildings. It consists of two and sometimes three panes of glass separated by a system of spacers and seals. It is that separation - not the glass - that provides the window with its primary insulating value.

The space between the panes is often filled with a heavy gas such as Argon or Krypton. Colourless and odorless, inert gasses don't easily allow air to pass through. In fact, Argon gas conducts 67% less heat than regular air, thus helping to keep building interiors cool during the day and warm at night. The seals that trap the gas between the panes of glass are clamped in place by aluminum frames which interlock with the adjacent frames, all of which are attached to the building itself.

Heat expansion damages seals: During the day, the sun's heat causes the exterior surface of the building to expand and contract while the interior surface remains relatively constant. Windows are designed with a certain amount of "give" to help withstand this uneven expansion. But over time, the continual expansion of the glass panes and aluminum frames puts stress on the window seals. The seals begin to break down.

Seals fail and gas escapes: As the window seals deteriorate, the inert gas that is responsible for most of the window's insulating value escapes from the window unit. Because the gas used in thermal windows is colourless and odourless, you won't be able to see that the window seal has failed. Building scientists can detect the failure by shining a laser beam through the window, and measuring the changes to the amount of light that emerges on the other side of the glass.

Although the escaping gas will change the window's thermal rating (from R-4 at the centre of the glass for a middle-of-the-road unit, to R-2.5 (R standing for thermal resistance), the more annoying problem will come as the window unit begins to fog up. Additional methods of analysing the thermal performance of windows are described in Mario D. Gonçalves and Robert Jutras' presentation at the 2007 Symposium on Building Envelope Technology. View Report [954KB .pdf]

Failed windows: The problems will be disguised for many years because the window frames are packed with desiccants - moisture-absorbing crystals. You've seen those tiny envelopes in the box for a new pair of shoes? It's the same principle - they help absorb moisture during shipping and storage. In the case of the window units, the aluminum frames are packed with strips of desiccant (circled left) to absorb water vapour. Desiccant plays a major role in keeping the glazing unit dry for the expected service life of the window unit. However, moisture entering through the seals will eventually overwhelm the desiccant, creating fog in what was once a dry space. You may not even realize your unit now requires more energy to heat and cool if the interior temperature is controlled by a thermostat. But you will certainly notice the foggy glass.

For owners who aren't aware that the expected service life of the window unit is a fraction of the life of the building as a whole, this may also be something of a surprise. For the first few years, the cost of replacing window units one at a time in individual condos will be annoying but not very expensive. However, at the 25-year point, as a growing number of window units fail, or if many of them fail earlier than expected, the condominium corporation will want to consider a complete replacement of the facade. Rising energy costs add pressure to make these changes to reduce the building's energy use.

For further reading on the choices that affect the service life of condominiums, see University of Toronto Professor of Building Science Ted Kesik's paper The Condo Conundrum.[250KB .pdf]

Residents of this Toronto condo at 81 Navy Wharf Court are suing the developer for alleged defects in the window wall system.

Throw-away buildings: Toronto's glass condos - Many of the glass condominium towers filling up the Toronto skyline will fail 15 to 25 years after they’re built, perhaps even earlier, and will need retrofits costing millions of dollars, say some industry experts. Buyers drawn to glass-walled condos because of the price and spectacular views may soon find themselves grappling with major problems including:

• Insulation failures.
• Water leaks.
• Skyrocketing energy and maintenance costs.
• Declining resale potential.

Glass condominiums — known in the industry as window walls — have floor-to-ceiling glass, so essentially the window becomes the wall. Window walls generally span from the top of the concrete slab right to the bottom. One developer calls glass-walled condos “throw-away buildings” because of their short lifespan relative to buildings with walls made of concrete or brick.

“We believe that somewhere between, say, five and 15 [years], many, many of those units will fail,” said David House of Earth Development, which bills itself as a socially responsible property developer. House, who also has experience in the standard development industry, spoke to CBC as part of a special three-part series on the issue that starts Monday at 5 p.m. and 6 p.m. on CBC News Toronto.

No other city in North America is building as many condo towers as Toronto, where they have reshaped the skyline, overshadowed once-prominent buildings such as the Rogers Centre and, in many areas, blocked Lake Ontario from view. About 130 new towers are now under construction.

Not energy-efficient: Glass walls have been popular among developers and consumers alike because they’re cheaper than more traditional materials and make a good first impression. But they aren’t energy-efficient and come with a hidden price that could soar down the road, engineers say.

Floor-to-ceiling glass walls heat up and swell in the summer, freeze and contract in winter, and shift with the wind, engineers say. The insulating argon gas between the panes escapes, the seals are breached and the windows are rendered useless against the city’s weather. Eventually, the glass walls — the skin of these condo high rises — might have to be replaced entirely, with condo owners picking up their share of the multimillion-dollar costs. “Now is about when we should start seeing trouble with 1990s buildings, with the glass starting to get fogged up, the rubber gaskets and sealants starting to fail,” said John Straube, a building science engineer at the University of Waterloo.

Windows tempt buyers: The glass walls that undermine a condo’s durability and energy efficiency are a key part of the attraction when potential buyers first step into those sunlit spaces overlooking the city. “To walk in and see trees, and just to see the city — it’s a wonderful thing,” said Kamela Hurlbut during a recent tour of a condo with her husband, Jason. For first-time buyers like the Hurlbuts, who eventually hope to own a detached house, a condo also seems the only affordable home-ownership option. Their estate agent, Linda Pinizzotto, emphasizes long-term costs as she tries to warn the couple away from glass walls. “As time goes on, what they have to be concerned about are maintenance fees,” Pinizzotto said. “There’s certainly a lot more care and requirements in the building if they have floor-to-ceiling windows.”

Glass-walled condos meet the requirements of the Toronto building code, although the code does not specify how long a building should last. Energy-efficiency is also a fuzzy area, since condos aren’t rated that way. "We don’t have energy-efficiency ratings on condominiums and that’s too bad, because we get them on dishwashers, refrigerators, and they only cost a few hundred dollars,” said Ted Kesik, a professor of building science at the John H. Daniels faculty of architecture, landscape and design at the University of Toronto.

Janice Pynn, president of the Canadian Condo Institute, isn’t sure energy efficiency is a big factor for condo buyers initially — even for buyers who care about not wasting energy. “People talk that they want it, but when it comes down to what it's going to cost them, it doesn't even come into the equation,” says Pynn, whose Simerra Property Management company manages 250 condos across the GTA. “It really is ‘Can I afford to buy this?’ not 'What am I willing to pay to have a green building, or a building in the long term, that will be far more economical, and cost-saving and for the environment?' They're just not asking those questions.”

Toronto may be leading all cities in North America for building condos but its boom could soon turn to crisis. CBC Toronto has produced an investigation into what it calls "throwaway condos" - in reference to the floor-to-ceiling glass windows, which may fail 15 to 25 years after they are built. Given Toronto's massive condo stock, that could equal a lot of failures. In simple terms, the glass window doubles as the outer wall of each unit. While it may make the building look sleek and modern from the outside, what's going on inside is cause for concern - due mostly to Toronto's seasons and temperature changes.

The freeze-thaw cycle that occurs in Toronto (and other Canadian cities who are erecting similar buildings) will eventually cause the sealant in the windows to fail, resulting in more hot & cool air getting into each unit. Condo residents will then have to crank up the heat or air conditioning to keep pace, resulting in higher energy bills. (Check out this graphic that explains how the failure happens). Its not just the higher energy bills that owners will be stuck with - "window-walls" cost a lot more to maintain than traditional building materials in the long run and these owners will be picking up a huge maintenance tab 20-25 years down the road, according to John Straube, a building science consultant and professor in the Department of Civil Engineering and School of Architecture at the University of Waterloo.

"We have a hard time," says Straube, "thinking five years when we buy a laptop, ten years when we buy a car. With these buildings — both the skin and the mechanical systems are going to have to be redone in a 25-year time frame. The concrete structure will be there a long time but in 20, 25 years time, we are going to see a lot of scaffolding on the outside of the buildings as we replace the glazing, sealants and the glass itself." Vancouver has had its own issues with leaky condominiums given its weather but with Toronto taking the lead in condo building and cities with similar climates like Ottawa, Montreal, Halifax and Calgary following suit, condo dwellers can expect energy and maintenance costs to skyrocket, all for the sake of living in a building that has style over substance.