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.”

The Toronto Glass Architect Argument

When you're dealing with floor-to-ceiling glass, you're just dealing with one trade." Along Burlingtons's waterfront is the Discovery Landing Centre and Cafe, Rotary Centre Pond, and Spencers at the Waterfront.

Seeing the (wet) future in glass buildings: Toronto, Mississauga and the greater Toronto area (GTA) need their glass consciousness raised. Building experts say resiliency and energy efficiency are going out the window with all those floor-to-ceiling glass walls being installed in the city's towering condos. "There's only one reason why all these buildings have floor-to-ceiling windows: it's because architects and builders are lazy, " maintains retired architect and developer Lloyd Alter, who writes for Treehugger and teaches sustainable design at Ryerson University.

"If you have a building that's brick and glass, you've got to hire a mason, you've got to hire a window guy and you've got to co-ordinate them. When you're dealing with floor-to-ceiling glass, you're just dealing with one trade." Ted Kesik, a professor of building science at the University of Toronto and an outspoken critic of the condo development industry, says he, too, worries that condo developers care more about profits than ensuring their buildings last. "I feel sorry for people in buildings like that, because those windows are going to fall out in an extreme weather event. There will be water damage. It's just going to be a mess."
 

Even Toronto's new chief planner, Jennifer Keesmaat, allows there's a problem with the windows' efficiency. "I share those concerns, " she says. "We need to be talking about this more as a city: how do we ensure that we do build buildings that have resiliency over the long term?" It's understandable, almost desirable, that developers want to move as quickly as possible. Keeping city roads blocked requires permits and frustrates the public. Logistics are a headache, especially for some of the newer guys on the building block who lack experience. And "window walls," the system most developers are using, are not as pricey, durable or difficult to put up as "curtain walls, " which is how Toronto's commercial towers were built. Time is money. But how fast is too fast?
 

For Alter, the main problem is energy efficiency. The glass has almost no insulation capacity. "When you look at the size of the little window that opens - because the building code says you have to have a little window in there — it's a little slot that's the size of an ice-cream stand pass-through, " he bristles. "There's no cross-ventilation. So they're constantly fighting to generate air conditioning, to generate heat, all because they've built these incredible dense buildings and they've given them these terrible, terrible skins."
 

But Arash Beheshti, vice-president of construction for Concord Adex, which is behind CityPlace, says it has to be a marketable product. "People want glass because they want to look outside, " he says, adding there are "misconceptions" about floor-to-ceiling windows. "Brick doesn't necessarily have a higher insulating value than glass," he says, pointing out that usually only one side of a condo is exposed to the outside while the floor, ceiling and sides are not. "When you look at the heat loss per unit of a condominium, you're looking at way less than at a house."
 

For Kesik, it's also an insurance issue. "Premiums are already rising because of climate change," says Kesik, who predicts that condo owners will see increases of 500 per cent over the years. Beheshti rejects charges that glass walls are more vulnerable to weather: "The exterior building envelope is actually more watertight, weather-tight, when you actually don't have multiple segments of different products. If it's all glass, it's actually more sustainable to the exterior weather than if you have brick-block-glass-concrete-wood."
 

When it comes to claims that glass towers use less energy, Alter is totally dismissive. "When you take the entire population of that glass building, and divide it by the entire consumption of that building, they will say this is green; we're using less energy per capita, " he says. "It's a fallacy. "If you look at the building as a whole rather than per capita, it's using a huge amount of energy that wouldn't have to be used heating and cooling because of all that glass." Kesik, an authority on retrofitting older buildings, also says you can't just tear them down and start over because, as experts agree, the concrete structures underneath these blue-green glass exteriors are built to last. 

"I have always maintained that, when you're looking at those glass towers there, you're basically looking at the slums of the future, " insists Kesik. "No one will want to buy them because people will look at them and say, ‘Are you crazy? I don't want to buy something that leaks, that will cost a fortune to retrofit.' So when they can't get sold, they'll get rented. And they're not of a high quality, so they can't get rented for a lot of money. So who do you think is going to live there? I tell people, this is where your grandchildren are going to come to buy crack. "No one wants to talk about these things because it gets people scared, " he warns. "The guys in the condos don't want to talk about it because they're sitting there saying, ‘You can't talk like that, you're going to devalue my condo and, if you devalue my condo, I am going to sue you for having devalued my real estate investment.' "This is how bad it has gotten. It's that cruel a joke."

2400 dead birds, victims of window collisions in Toronto in 2012 on display at the ROM. Click to enlarge.

Birds killed flying into buildings on display at Toronto museum: Visitors stepped into the Royal Ontario Museum this week for a look at a piece of urban history — a layout of dead birds that had collided with Toronto buildings. The Fatal Light Awareness Program, or appropriately, FLAP, hosts the yearly exhibition using collected corpses of birds that were victims of window collisions. Sounds like messy work.

Next to artifacts from ancient Cyprus and historical architecture from China, dead birds seem like a bizarre choice for a museum. But there's a point to make here. It's that Toronto, not only its people but its very existence, is deadly to birds. About a million birds are killed every year after colliding with buildings in Toronto, according to research by FLAP. Since birds have no concept of glass, reflective windows trick them into thinking there's clear sky before them, when in fact there's an office tower. Birds also become disoriented because of bright lights shining through cities at night, according to the organization. The troubles of a migrating bird don't stop there. You try flying south across an entire continent while dodging wind turbines, condo buildings and Lachute, Quebec.

More blogs on bird-strikes here.

Glass Curtain Walls From China - Limited life

Window washers on the 60-story, glass-walled JW Marriott Hotel Shanghai.

Glass-covered towers nearing critical age: China's first buildings to feature glass curtain walls will reach the end of their design life in the next few years, prompting experts to call for better maintenance of the structures to prevent accidents. Glass curtain walls, in which a building's facade is made of sheet glass held in place by framework, began to appear in Chinese blueprints in 1984, and have an average design life of 25 years.

The durability of supporting parts, such as bolts and sealant, is generally 10 to 15 years. In Shanghai, about 900 of at least 4,000 such buildings are more than 15 years old. "But that doesn't mean they should be replaced by new ones or demolished immediately," said Lu Jinlong, deputy director of the Shanghai Research Institute of Building Science. "They can be used for some time if regular maintenance is done well."

China builds 70 million square meters of glass curtain walls each year, according to the China Architectural and Industrial Glass Association. The cost of replacing these could be enormous. "Who should be responsible for the large sum? The developers or the maintenance companies?" said Li Dexiang, a professor at Tsinghua University's School of Architecture. "The problem is there, but there's no efficient solution yet."

Some buildings with glass facades overseas are still in good condition after 50 or 60 years, thanks to timely maintenance. But there have been many cases in China of glass curtain walls in high-rises bursting without warning. In Hangzhou, Zhejiang province, a 20-year-old woman was hit by shards of glass from a window that burst in a glass facade as she walked down the street on July 8. Part of her left leg had to be amputated.

A month later in Yiwu, Zhejiang province, a 20-meter-high glass ceiling in a garment market came crashing down, injuring several children, one seriously. Shanghai enacted a management regulation for glass curtain wall construction on Feb 1, establishing a fund collected from developers and owners of such properties for maintaining and repairing glass curtain walls.

"However, there's a long way to go between setting up the fund and using it to have the glass curtains in good condition in Shanghai," said Lu, of the building research institute. "Let alone in other cities, which don't have such a regulation or plans."

China released a building code for glass curtain walls in 2003, but no guidelines have been issued on who is responsible for the maintenance. According to Motian City magazine, there were 350 buildings higher than 152 meters, and another 287 under construction on the Chinese mainland in March. "The number of completed super high-rises may increase by 10 percent this year," said Wu Chengtao, the magazine's editor-in-chief.

"But the construction of many glass curtain wall buildings takes only the charming exterior into account," he said. "First, they invest more than hundreds of millions in the construction. The cost for later repair and maintenance comes to no small sum," Wu said.

On July 8, when a 19-year-old girl named Zhu Yiyi was walking past a 23-storied building in Hangzhou, a glass curtain wall fell from the 21st floor and hit her, leaving a 20-cm laceration on her left lower limb, severing the arteries in her left thigh, and fracturing her thighbone. Her vessels, muscles and tissues in the left lower leg were also severely damaged, which means amputation at the knee would have been the only viable treatment.

19 year old Zhu Yiyi faces amputation after her leg was virtually severed by a shard of falling glass from a commercial building in Hangzhou, the capital of eastern China's Zhejiang Province on July 8. Zhu is now in a Shanghai hospital for surgery in hopes of preserving most of her leg. Though in stable condition, Zhu must sleep in a corridor because the hospital has no beds available. A sheet of glass, measuring 1 meter in length, dropped from the 21st floor and hit Zhu from behind on her knee as she walked near the 23 story Qingchun Development Building on her way to work. "At that time, I felt extremely painful and I was bleeding seriously. I was very weak and just wanted to be alive," said Zhu Yiyi.
Witnesses said her left leg was almost cut off beneath her knee. Doctors in the Hangzhou hospital said that due to the severe damage to the blood vessels and nerves, Zhu might lose her leg. In order to keep her leg, Zhu's parents, farmers from a village in Jiangxi Province, took her to Shanghai right away to receive better treatment. The father said they hoped the hospital could save her knee so that she could walk with an artificial limb after surgery. A doctor said the hospital would try to move Zhu into a ward from the corridor soon, and promised to let the best doctor perform the amputation. "Amputation is necessary for her and we are concerned where to conduct the amputation. We are trying to conduct it on a lower place of her leg. If we conduct the amputation under her knee, the artificial limb will be functioning in a better way," said Zhang Tao, Executive Director of Orthopaedic Department of Shanghai No. 8 People's Hospital.
Zhu's family is not wealthy and she gave up her education after high school to work in an architectural design company in Hangzhou. Though the sudden disaster has challenged her in an arduous way, she remains positive about her future. "I believe that I will be like a normal person once I have my artificial limbs on. I can do nothing but to face and accept the situation now," said Zhu. "I blame no one, but hope similar tragedies will never happen to others. I still feel optimistic about my future. For example, I can be a senior architectural designer. I can earn more money. I can also find my Mr. Right to love for the entire life," Zhu also said.
The building's property management company issued a written guarantee to Zhu to cover all her medical expenses. Zhu Meilong, the father of Zhu Yiyi, explained that the company initially refused to take full responsibility and gave Zhu only 30,000 yuan in compensation, which was less than the 40,000 yuan needed for medical expenses. He also said the company agreed to pay more after a Hangzhou law firm helped Zhu negotiate with the company voluntarily. Hangzhou police were still investigating who was liable, but Dai Heping, the head lawyer of the law firm who is helping Zhu Yiyi free of charge, said both the property management company and the tenant of the floor, a paper-making company, should be held responsible. 

Tempered glass breakage: A frequent misconception about tempered glass regards its resistance to breakages. Many consider it "unbreakable" or "nearly unbreakable". Such is not the case. As with every other type of glass, also tempered glass can break. Glass breaks when it is exposed to stresses that it cannot withstand. To increase its strength and heat resistance annealed glass can be subjected to a thermal treatment or chemical process. Tempered glass is obtained using this process, and its final form is four to five times as strong as annealed glass of the same type and thickness. When broken, it shatters into many small fragments, which prevent major injuries. Due to these characteristics tempered glass is used traditionally in applications requiring increased strength and reduced likelihood of injury in the event of breakage.
Tempered glass should receive the same care as annealed glass. Unfortunately, the perception of "unbreakable" characteristics of tempered glass may mislead people to provide less care while handling it. Careless handling and improper installation sometimes produce damage, which leads to "spontaneous breakage" or "delayed breakage." This means that occasionally a sheet will not shatter immediately at the time of damage, but perhaps weeks later. Inclusions in glass such as NiS can also trigger a delayed breakage effect. Nickel sulphide inclusion, also known as NiS, occurs during the manufacturing process for float glass. In a glass batch, nickel-rich contaminants such as stainless steel might be present, and then combine with sulphur to form nickel sulphide inclusions. To minimize the risk of NiS breakages, a heat soak test is performed. Although some spontaneous breakages occur due to the above-mentioned factors, much breakage is called "spontaneous" just because there is no easily visible cause.