A harmful trade-off many U.S. green buildings make
The last time buildings were as poorly insulated as they are today was 500 B.C.
“Green” construction in the U.S. has mostly been on a fad diet – one where trimming energy consumption is focused on the present but not the long run. That is the conclusion that New York-based nonprofit Urban Green Council found in their research on “high cholesterol buildings.”
The research is aptly named because how many buildings are insulated today focus more on how aesthetically pleasing the building will look, and all the green technology is clustered into what HVAC and other mechanical systems will the building be equipped with.
One example of such a trade-off of aesthetics and actual sustainability is in the selection of a building’s envelope: subpar walls, windows and roofs. “Unlike mechanical systems like air conditioners and ventilation fans, a building’s envelope is one of its longest-lasting components,” the report says.
A curtain wall made out of, say, glass, a notoriously poor insulator, has been a popular material to design and construct a building. The final building with all floor-to-ceiling windows, as the report boldly says, is as poorly insulated as a building from over a millennium ago.
However, the envelope of a building outlives all the other components; as lighting and HVAC systems are replaced with new, more efficient ones, a poorly insulated envelope will drag down the building’s potential of being at its most energy-efficient (see chart below).
The research pushes for loopholes in building codes to be closed. Currently, most green standards focus more on reduction of net energy consumption, hence, they make a trade-off where “they add more glass and make up for it with superior mechanical systems,” because floor-to-ceiling windows are a great selling or renting point and are in high demand.
Other recommendations the Council makes are for better glass, better design, and better training of contractors and subcontractors to stress on air sealing and elimination of thermal breaks.
The full report can be read in PDF here.