A recent discussion with a colleague as well as this article on treehugger raised questions about the ethics of designing buildings with large areas of curtain wall, especially in the northeast and other ‘temperate’ climate zones. We see glass-clad buildings going up everywhere (including some of our own), and often described as “sustainable buildings” and awarded LEEP Platinum. How is this possible when we know that the typical curtain wall system performs only at around R-3? Even the best triple glazed, thermally broken, low-e coated systems available in the US achieve only R-5, and that’s the design value. (As we know, actual performance is often much poorer). Spandrel hardly performs better at R-4 when taking into account the thermal bridging caused by metal back pans. Compare this to our typical wall system which is designed to an average R-15.6 (center of wall).
The argument can (and has) been made that architects are powerless to design more sustainable building envelopes because ‘this is what the market wants.’ I would argue that we have a responsibility to strive to design the most sustainable building possible. At PAYETTE we are certainly capable of designing buildings that use a variety of building envelope systems, but many of our buildings today do have some large areas of curtain wall.
If we accept that we have a responsibility to design the most sustainable buildings possible, can we justify the use of any curtain wall? Can we use curtain wall, but only if we specify imported ultra-high-performance systems? (I have read that curtain wall with an R value as high as 14 is available in Europe.) Can we use curtain wall if we utilize double-skin facades or other types of thermal mitigation zones such as the “thermal corridor” employed in our current project at Duke University?
I’m curious what others think about this apparent clash between the desire for a particular aesthetic and the reality of building envelope performance.
Further reading:
“Glass Towers May Be Sexy, But They Need to Put a Coat On”
“Can Fully Glazed Curtainwalls be Green?”
“Curtain Walls and Energy Codes”
Kawneer’s super-duper triple-glazes curtainwall
At PAYETTE, we value the inseparable connection between architecture and landscape. Our “Embedded Nature” approach emphasizes the importance of incorporating nature into even the most complex urban environments, fostering well-being for mind, body and spirit.
Read more about our Landscape team and their brand new website page in the link in bio.