At some point in the last 20 years, glass began to replace stone in Austin’s tall downtown buildings. That meant that as the city’s skyline inched taller, it turned from brown to blue, like an ocean tide creeping up onto a mound of dirt.
Aaron Madison noticed this change. The 41-year-old drives for Uber and often picks up and drops off passengers downtown, where he finds himself weaving in and out of cobalt towers.
“They’re all just these big blocks of blue glass,” Madison said, referring to the city’s skyscrapers. That got him wondering: “Why [do] so many of the new buildings downtown have the same shade of light blue glass?”
Look to the sky
The answer to Madison’s question has less to do with the color of the glass and more to do with the color of the sky.
“You put a little reflectance in [the glass] and of course it’s reflecting the sky,” said Larry Speck, an architect and professor at UT Austin's School of Architecture.
Speck, a senior principal with the architecture firm Page, has helped design some of Austin’s tallest buildings. This includes the Indeed Tower, plus 70 Rainey and 44 East, both luxury condo buildings.
Each of these towers appears blue because they're made of highly reflective glass and the glass is reflecting the sky.
“In Austin, we have a really, really vivid, wonderful blue in our sky," Speck said, “and when that gets reflected a little bit it begins to make it look like, ‘Oh, that’s a blue building.”
Consider another iconic downtown structure: the Independent, a 58-story condo building. (You may also know it as the Jenga Tower, an apt nickname given the building’s jagged design.) The building was designed by architecture firm Rhode Partners.
“If you’re looking at the Independent project this is the ‘blue glass,’” Brett Rhode said, holding up a square of thick gray-tinted glass. “It doesn’t really look that blue.”
But on a sunny day the building appears more blue than silver.
Let light in, keep heat out
In the early 20th century, as buildings got taller, glassmakers ran into a problem: how to let light in while keeping heat out. Cooling systems in tall buildings with tons of glass had to work overtime to keep the building’s residents from burning up.
While architects and builders tried to solve this problem, some architects did away with windows altogether and began touting the virtues of windowless buildings. An advertisement from the 1930s for a building in Massachusetts highlights its many selling points: “No windows! No shadows!”
By the midcentury, glass technology had evolved so that windows could more effectively let in light while keeping out heat. How? Super reflective glass. Mirrored glass.
“That’s really the only technology that was available at the time,” said Emily Losego, a director at Vitro Architectural Glass in Pittsburgh. “That’s why there’s those buildings that everyone remembers that are just like these reflective boxes that you think are just so god-awful.”
In the 1970s and 1980s, downtown Dallas was a veritable museum of these “reflective boxes.” (Whether it's "god-awful" depends on your taste.) Builders finished the Campbell Centre, a set of office towers, in 1977. The buildings featured flecks of real gold in the highly reflective glass. There was also the dark, mirrored glass of the Trammell Crow Center, built in the mid-1980s.
But while the mirrored glass of these skyscrapers served a function — Light in! Heat out! — the aesthetics did not withstand the test of time. Both of these buildings have since been redesigned.
When glass is too reflective
In 1974, builders completed one of Austin’s first skyscrapers, the 21-story AmericanBank Tower on West Sixth Street. The building was clad in gold, reflective glass. A reporter writing for the Austin Statesman referred to the bank building as the “$17 million golden mirror.”
The name stuck.
Speck, the architecture professor, lived at the time in a neighborhood just west of downtown. At sunset, rays of light would bounce off the bank tower and into his home, creating a blazing halo.
“If I sat on my front porch it was like looking straight into the sun,” Speck said. The light heated up his house. “It was unbelievable the intensity of that light … in the summertime it was awful.”
A columnist for the Austin American-Statesman wrote in 1973 about the experience of driving into downtown during a fall sunrise.
“The morning sun was shining on the gold wall of the New American Bank building and the reflection became a path of gold on the street,” the reporter wrote. “As one drove into the area, the shimmer of the gold reflection enveloped the car and filtered to the inside.”
Eventually, Austin’s “Golden Mirror” got a makeover. Investment firms bought the building in the early 1990s and replaced the gold exterior with gray-tinted glass. “No more gold box,” Bill Walters, a broker who represented the building’s new owners, told a reporter.
As the building changed ownership over the years, it became known as the Chase Bank Tower and most recently, the Procore Tower.
Modern reflective glass
How did we go from windowless buildings to heavily mirrored glass to the modern era where every glass skyscraper looks blue? In the 1980s, glassmakers came up with an alternative to mirrored glass. They began putting very thin coatings of metal, usually silver, between the panes of glass used in tall buildings.
The metal coatings, known as low-emissivity or low-e coatings, are effective at letting in light while keeping out heat.
Glassmakers can tweak the ingredients in the coatings to let different kinds of light in. And reflectance, or how reflective the material is, is still one ingredient in these coatings. It’s remains an important factor in creating efficient skyscraper glass.
And, it means Austin’s downtown buildings reflect the color of the sky — which can change depending on the weather.
“Whatever you see going on outside that day you will see reflected in the glass,” Juliana Felkner, a professor at UT Austin’s School of Architecture, said.
But here in Austin the sky is often blue. So, too, are our buildings.
