The team sought a solar film that wouldn’t block any visible light but would block ultraviolet and infrared rays, which would contribute to cooling loads. “We did a model and were able to ‘tune’ the film based on the elevation it is placed on the building,” Rode says. “We looked at the effects of bringing natural light in compared to artificial lighting and got the right balance so we weren’t using more energy through artificial lighting and were reducing heating and cooling needs.”
Rode says it was more economical to retrofit the building’s existing windows than buy new high-performance windows. “What a shame it would have been to throw away more than 26,000 panes of glass—and what an expense in Manhattan!” he says. “Not only did we avoid throwing windows out, we also avoided the costs of trucking and distribution.”
It took about nine months to retrofit all 6,514 windows, and Rode is proud of the project because it is achieving the results the team expected. “The R-values and coefficiency are holding up,” he says. “By doing the windows, we removed so much air-conditioning load we prevented the cooling plant from increasing in size for conditioning the hallways.”
From the Top
In addition to the window retrofit happening throughout the Empire State Building, a major glass replacement took place in the building’s upper observatory on the 102nd floor—almost 0.25 mile above the ground. The round observatory is small, approximately 40 feet in diameter, and completely enclosed with 32 lites of glass that encircle the perimeter of the room.
The existing single-pane 1/2-inch monolithic glass featured a radio-frequency-repellent film but provided no thermal performance. The film was deteriorating, which was affecting the clarity of the glass. Brooklyn, N.Y.-based Kilroy Architectural Windows had replaced the building’s 6,514 windows 14 years previously and was invited to install the new glass on the observatory.
“There were a number of design issues that had to be addressed,” explains Bill Kennedy, Kilroy Architectural Windows’ senior vice president. “One was the need for scratch-resistant glass on the interior. Another was very high thermal values. Lastly, the space needed a glass package that would repel any radio waves from the antenna equipment on the top of the building.”
In addition, public safety and glass clarity were of utmost importance. Kilroy Architectural Windows collaborated with Johnson Controls and the rest of the dream team to create a unique glass unit composed of three different manufacturers’ products that each met individual design requirements.
On the interior face, Auburn Hills, Mich.-based Guardian Industries Corp.’s UltraWhite low-iron glass with DiamondGuard coating, which protects glass from scratches, smudges and haze, was specified. The exterior pane is Datastop, which reduces the transmission of electromagnetic radiation and is manufactured by Toledo, Ohio-based Pilkington. Suspended between the two panes of glass is Serious Materials’ clear aluminum solar film—the same film installed in the 6,514 windows throughout the building.