Gensler's 811,000-square-foot terminal at PIT opened with clerestory glazing engineered to preserve the illusion of dappled canopy light without punishing HVAC. Here's how a triple-silver, low-iron IGU cleared both the aesthetic bar and the ASHRAE model on a LEED Gold pursuit.
Pittsburgh International Airport's Terminal Modernization Program spent more than a decade in planning and four years in construction. The clerestory spec sheet, however, came down to a single question every architect designing under a mass-timber roof eventually asks: how do you keep the daylight without inheriting the solar load? Vitro's new project write-up—published this month by Building Enclosure and Glass Magazine—walks through how the design team solved it.
The Project: Mass Timber, Steel 'Tree Trunks,' and Clerestories That Weave Through the Ceiling
Featuring an undulating mass timber roof, steel beams mimicking tree trunks and branches, and expansive clerestory windows, Pittsburgh International Airport's new 811,000-square-foot terminal officially opened in November 2025, designed by Gensler with outdoor terraces incorporating native plants, walkways and benches, and a wavy wood ceiling referencing the rolling hills of the Allegheny Mountains.
The biophilic intent was explicit. "The undulating roof design is intended to evoke impressions of being under a tree canopy. The shifting light from the clerestories is like dappled sunlight that filters down through the leaves," said Carolyn Sponza, project director at Gensler Pittsburgh. A total of 38 unique, architecturally exposed structural steel (AESS) hollow beams filled with concrete cast a copper hue, creating the look of sunlight filtering through the canopy.
For the clerestories weaving above and below the dropped timber ceiling, the team wanted the clearest glass they could get—without giving mechanical engineers a load problem.
The Spec: Solarban 72 Starphire at VLT-68/SHGC-0.28
The design team prioritized a highly transparent glazing solution that would maximize clarity and daylight while working in harmony with the building's mechanical systems. By balancing aesthetic and performance goals, the selected glass helped minimize energy demands, avoid increased HVAC loads and support long-term operational efficiency. Ultimately, Solarban 72 Starphire glass from Vitro Architectural Glass was specified, delivering a VLT of 68% and SHGC of 0.28.
For spec writers, that VLT-to-SHGC ratio—roughly 2.4—is the number that mattered here. It is the light-to-solar-gain metric that separates ordinary tinted or mid-tier low-e from triple-silver low-iron IGUs, and it is why the product keeps showing up on daylighting-driven projects with strict energy models.
How the Team Validated It
The modeling workflow is worth noting for anyone specifying against ASHRAE 90.1 targets: to verify these values and compliance with ASHRAE Energy Sim Standard, the Buro Happold engineering team used Integrated Environmental Solutions' modeling software. "This helped us validate the performance of the glass within the overall strategy," added Sponza.
That is not a small point. On an 811,000-square-foot envelope with continuous clerestories, the difference between a data-sheet VLT/SHGC and an as-modeled result across orientations and shading conditions is where LEED energy points—and mechanical sizing—actually get won or lost.
Performance Beyond the Numbers
The glass had to do more than clear the energy model. By maximizing diffused daylight while minimizing glare, the clerestory system reduces reliance on artificial lighting during daytime hours, contributing to overall energy efficiency. Solarban 72 Starphire glass helps maintain consistent interior temperatures, mitigating hotspots and improving thermal comfort in large, open spaces. Additionally, the clarity of the low-iron glass preserves true color rendering, allowing architectural materials to be experienced as intended by the design team.
Color rendering is the quiet argument for low-iron substrates on mass-timber projects: standard clear float pulls a green cast that reads visibly against warm wood tones. On a design intended to evoke Allegheny hillsides through copper-hued steel and Queensland-scale timber ceilings, that cast is not a nuance—it is a rejection at mock-up.
The LEED and Microgrid Context
Complementing the high-performance glass, the terminal incorporates rainwater harvesting, locally sourced materials and an on-site microgrid, making the airport electrically self-sufficient. Pittsburgh International Airport is seeking LEED Gold certification for the new terminal. The project is completely powered by a microgrid using natural gas and solar energy.
The glazing package supports both operational and material sustainability goals through third-party verified Environmental Product Declarations and low embodied carbon documentation—increasingly a baseline expectation on LEED v4.1 material credits, not a differentiator.
What It Means for the Spec Sheet
For architects and building envelope consultants working on transportation, higher-ed, and civic projects with mass-timber ceilings:
- Triple-silver low-iron is now the default answer, not the premium upgrade, when the design intent is "clear" and the energy model is tight. A VLT of 68% with SHGC of 0.28 is what makes clerestory-heavy schemes survive value engineering.
- Model early, model with the actual product. Buro Happold's IES workflow, running verified Vitro data against ASHRAE compliance, is the pattern to copy—not a one-off.
- Color rendering is a real spec criterion on wood-forward projects. Standard float will fight the palette. Low-iron substrates like Starphire are what let designers hit the Allegheny-canopy or Queensland-ironbark look without the green wash.
- Microgrid-powered terminals raise the bar for envelope performance. When the building generates its own power, every watt of avoided cooling load is worth more than in a grid-tied facility. Envelope-first thinking is not just a code conversation anymore—it is an operations conversation.
PIT is not the first triple-silver, low-iron airport clerestory to be delivered. But it may be the clearest recent illustration of why the glazing spec drives everything downstream when the ceiling is timber and the design story is daylight.