The Weird Flaw Plaguing Skyscraper Windows

-Refused to do a 3 million $ replacement -Killed a mother, spent 18 million $ in settlement, and still have to do the replacement after that I wonder how many corporate decisions ended up that way

Windows keeps crashing, as usual.

It's always cheaper to do the right thing. CNA could have replaced the windows first and saved $18 million and someone's mother.

I am impressed that he was willing to stand under that precarious tower. Imagine the headline: "Architect Struck By Falling Glass While Making A Documentary About Falling Glass."

Building thermal engineer here. Low E glass films and coatings don't change the radiated heat absorbed from sunlight. They change the conductive heat transfer, so that the wind doesn't pull heat through the glass as easily. Regular tints absorb light rather than letting it through the glass, and mirror tints reflect that light rather than absorbing it. So a mirror tint is the only thing which will reduce the heating of the glass itself.

Contract Glazier here, This video is awesome and explains my job of assembling the building envelope so well, and by one of my favorite youtubers! but a couple of notes: First, low e is rarely a film these days, now it is a coating applied to the glass just after the float process. second, Wind load is often miscalculated, and reduced to a simple "wind factor" for different jurisdictions that doesn't actually give enough information to us glaziers to determine if thicker or laminated glass is required. third, 99.99% of modern buildings are glazed with 1" IG units consisting clear tempered glass. many times, a cracked window is brushed off as it is on the outer lite and therefore the resident or tenant will feel its ok so long as outside air isn't getting inside. Fourth, heat strengthened glass is no longer standard, and sometimes even not code. Nowadays, if you want stronger glass, you purchase what is called heat soaked tempered glass, which is standard tempered glass that is "soaked" in a heated oven, and will break roughly 50% of the panels and the panels that survive are rated to only break 1/100,000 times. Fifth, EVA is being removed in many cases for its ability to absorb moisture. PVB on the other hand does not have this down side. SGP is also used as a lamination layer where structure is needed as it is a stiff interlayer allowing the glass to remain in place and in shape once the individual lites have burst. Sixth, $3,000,000 is a 1990 price for the replacement for sure, modern glaziers would charge closer to 26,000,000 to replace all the glass in the CNA building with current safety and energy standards. Lastly, many of these standards and safety requirements are not looked at by the owner or contractors, the ARCHITECHT dictates their standards and specifications for the building, and if they dont spec the safest material, we as contractors wont price the safest material, as we don't want to lose the bid to a company that doesn't care since safety has an additional cost, so while we do care, we can't do much other than plead with the general contractor to plead with the architect.

2:36 that's why you don't take your marble for granite

Thank you for saying "inaccurately balance risk and cost" rather than pretending we don't have to balance risk and cost.

Even if a tempered glass was more likely to fall out when breaking, it still feels safer to have a higher probability of minor injury vs a lower probability of serious injury or potential death. Minimizing catastrophe (like the tragic death of the mom) feels more important than minimizing injury. We need to consider failure modes in addition to failure likelihoods. That film worsens the failure mode and should never have been considered.

The irony of keeping up scaffolding (a non-permanent structure) permanently in the name of safe building facade inspections is not lost on me.

I went to college in Boston in the mid 1970s. When I moved there, the John Hancock Tower in Copley Square had just been completed after terrific problems with its glass curtain wall. About half of the building's glass had popped out and fallen to the street during construction. For years most of the tower's facade was covered in plywood panels. People joked that it was "the tallest wooden building in the world." By the time I moved to Boston all the glass panels had been replaced, but the memories were still very fresh. While the original glass was a major part of the problem, it turned out that the building was oscillating in the wind far more than anticipated, which contributed to the problems with the glass. The building needed to be structurally reinforced, at great cost. Fortunately, it hadn't been occupied yet, but as a result the opening was delayed by about four years. It is a beautiful feat of architectural sculpture, due to its shape and reflective glass. From certain vantage points ot practically disappears or seems like a two-dimensional cutout on the skyline. From the structural point of view, it was a powerful and very expensive object lesson in engineering hubris.

The New York sidewalk "sheds" aren't there semi-permanently either because they're needed for inspections (they aren't) or because they'd be expensive to remove. Instead each one represents an instance where a potentially dangerous façade has been identified by inspection and so the protective shed mandated but it's much less expensive to pay the fines imposed by Local Law 11 — not revised since it was introduced — annually for not doing the repair than it would be to repair the building. If the city would just update it's schedules of fines in line with inflation more repairs would be done and so more sheds taken away. Just another example of New Cork City's love of incompetent governance.

The Bernoulli effect may not be a commonly understood concept, but pretty much everyone in Chicago gets it on practically an instinctual level. Walking around a tall building between the high pressure and leeward sides allows you to experience the effect firsthand — watch as people brace themselves as they enter the low pressure zone and also pay attention to where the smokers gather (lol).

Car side windows are tempered, and windshields are laminated. It's interesting to see how that works out at a larger scale!

Canada's tallest tower outside of Toronto, the 251m tall Stantec Tower, in Edmonton has been notorious for his shiny glass facade cracking and smashing into the ground below ever since it was opened back in 2018... For a while there was a pane a month falling from the tower it seemed. While it may not have been that bad it did kill all semblance of pedestrian traffic in the area and as a result a lot of the development in the surrounding ICE District has failed to flourish. Food hall? Still just a shell 6 years later. Cinema complex? Scrapped. Pharmacy? Shuttered after less than a year in business... I know I've only been to it twice or thrice since it opened and I basically sprinted through the plaza on the way to the arena. Maybe there's something to be said for more traditional facade materials besides wafers of melted sand...

The loss of windows at the Sears Tower came from failures in the outer skin of the glass. Slag from welding on higher floors scarred the glass below allowing it to fail.

Wow for most of this video, I didn't think the building owner was that negligent. But then when he said that the window that fell and killed someone had the film on it and just was put off and pushed down the list of repairs really changed it for me. Can you imagine being one of their family members? The building is freaking red so it catches your eye. I bet every time they see it, it brings back some part of the pain from losing them. It's ironic too that it would be a red building. It's almost like they have been warning people to stay away since the beginning because red often means danger

Great video Stewart, I'm going for a job interview tomorrow for a glass manufacturer and you bring up some great points of how the designs can fail.

omg. When you're hear that the falling pane was one of the "repaired," windows, you can't help but feel your stomach drop. There have been a number of pieces of glass fall here (Calgary) but to my knowledge, no one has been killed. We are in an area with extreme winds similar to Chicago: it's not unusual to have 60mph straight line winds once or twice a year, and every year has many days with 50mph winds. As far as I know, that's at the surface; I'm not sure what it is in high rises. I believe many condo buildings have bylaws regarding securing things on their balconies. I'd be very curious what they've done with the fenestration here regarding heat treatments, because we also have a huge diurnal variation in temperature. Sunny days can rise from 32F to 70F air temperature, and I'm not sure what that would translate to for glass surface temps in the sun.

And that's why the wind is so bad in Chicago because you've got all different shapes of buildings and that wind is coming off the lake like nobody's business