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Is the “Glass Box” Going Out the Window? These Building Enclosures Aren’t Making the Grade


Designing or recladding with a glass building enclosure during the time of COVID-19 has brought up issues beyond energy performance. Among the many attractions of glass is, of course, beauty. But equally or more important is occupants’ physical and mental health, which can be more dependent on things like natural daylight, connection to the outdoor environment and visibility beyond opaque walls, and less dependent on energy savings metrics…especially now, when healthy air flow is probably the most important HVAC consideration.

Depending on one’s perspective, usually Form Follows Function. The-55-story, 10,000 occupant Bank of America Tower in Midtown Manhattan was designed (form) with environmental performance (function) in mind. The “glass box” new construction achieved LEED® Platinum Core and Shell, but the project received a D grade from the city of New York for its annual energy performance, based on NYC Local Law 84 performance reporting. The Tower has the highest site energy use intensity (211 kBtu per square foot) of all super large office and financial institution buildings.

The solar heat gain caused by glass building enclosure increases the load on space-conditioning systems, over-exerting mechanical systems and wasting energy. The poor insulative properties of glass (as in, generally R-3 at best) require larger-scale emergency generators, which must be tested regularly to ensure they work.

The question is, what will be the trade-offs, and/or how can performance be measured differently, to accommodate the need for a healthy, comfortable working population and the desire to mitigate and sustain environmental impact?

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