Populus. Studio Gang. © Jason O’Rear
A recent New York Times article focused on the Populus Hotel in downtown Denver, Colorado, particularly on whether the building—a visually striking design by Studio Gang—meets its extravagant sustainability claims. In questioning how the Populus achieves its assertions of being “carbon-positive,” the Times also highlighted dubious sustainability claims throughout the construction industry.
Because the construction industry is responsible for an estimated forty percent of carbon emissions worldwide, architects have tried to combat the negative impact that building has on the environment. For marketing purposes, developers and architects have begun branding projects with oversold phrases that, in some cases, mischaracterize their eco-friendliness. And sometimes these projects have been criticized as greenwashing.
Even a reputable firm such as Perkins & Will has taken heat for some outlandish proclamations made about their SoLo House in British Columbia, going as far as to say that “buildings can counteract their negative consequences and act as a source of repair.” Perkins & Will deemed the SoLo House “beyond carbon neutral” based on its own interpretation of embodied carbon. As long as architects are allowed to invent their own algorithms, some of them are bound to exaggerate their calculations. The result is a slew of buildings described as “beyond carbon neutral” or “net-zero” or “carbon negative.”
SoLo. Perkins & Will.
Similarly, Norman Foster has been criticized for buildings such as the JPMorgan Chase Building at 270 Park Avenue in New York, which markets itself as “all-electric” and boasts “net-zero operational emissions,” despite lacking a renewable energy component. By not producing its own power (either through solar panels or wind turbines), the JPMorgan Chase Building draws from the electrical grid, which produces carbon emissions.
While some architects make wild claims based on abstruse calculations, others oversell concepts. In the case of mass timber, for example, carbon sequestration became the exaggerated element. Even though mass timber already has a substantial advantage over steel and concrete—producing mass timber, although not without its own drawbacks, is far less carbon-intensive than producing steel or concrete—architects insisted on inflating carbon sequestration. Trees act as a carbon sink, removing carbon dioxide from the atmosphere during photosynthesis, and when a tree is harvested for construction, the carbon it has absorbed throughout its lifespan remains in the wood, giving timber one of its sustainability edges. But this edge is diminished by the fact that much of the tree is not used for construction after harvesting, leaving sawdust and chips to potentially decompose.
The rise of—and subsequent backlash to—mass timber reflects how difficult it is to eliminate carbon emissions from the building industry. In fact, it is almost impossible for even the most eco-conscious project to manage such a feat. Carbon emissions are produced in two ways: by the construction process (producing concrete and steel, for example, and transporting it) and by the operations of the structure once it is built (energy usage from mechanical elements such as air conditioning). Generally speaking, the most effective way to significantly reduce both methods of emissions is by combining adaptive reuse with renewable energy strategies. Renovating existing buildings eliminates the construction process altogether and reduces material waste via recycling, while retrofitting these buildings with solar arrays and updating antiquated HVAC systems further minimizes carbon emissions. As has been mentioned on Studio St. Germain before, the exemplar for this kind of programming is The Marcel, a net-zero hotel in New Haven, Connecticut, which re-modeled a standout but desolate Brutalist structure designed by Marcel Breuer and upgraded its systems to all-electric, significantly reducing its carbon footprint.
The Marcel. Becker + Becker
No matter how friendly recycling is for the environment, however, new construction will always supersede adaptive reuse—which is why architects have adopted more roundabout ways to affirm their commitment to green design. Two murky strategies that have been used by architects and developers to burnish their sustainability credentials are carbon offsets and carbon credits.
Carbon offsets that rely on planting trees elsewhere to balance emissions produced by construction are particularly tricky. For one thing, it takes years for a tree to grow into its carbon-sequestration phase; for another, there is no guarantee that a tree will not die prematurely from either disease or from wildfire.
Even worse is the carbon credit strategy, where developers pay a third-party to take emissions-reducing actions on their behalf. This strange market has already been undercut by withering exposes in The Guardian and elsewhere. Simply put, too many carbon-trading entities are unregulated enterprises that allow major corporations to greenwash their half-hearted environmental overtures.
Ultimately, the real damage done by these carbon offset strategies is that they may convince developers and architects to view them as alternatives to legitimate sustainable design strategies.
As for the Populus, its sustainability component may not meet the standards of purists, but its carbon-mitigation program is fairly extensive. “The Populus’s approach started at construction, with a concrete mix said to emit 30 percent less carbon dioxide than regular concrete,” notes the Times. “Repurposed elements are heavily relied on, including wood from an already felled cottonwood tree for the reception desk; beetle-kill pine for some walls and bed headboards; and snow fencing from Wyoming as decorative ceiling beams. The 365 glass-fiber-reinforced concrete panels on the hotel’s exterior, inspired by the bark of aspen trees, help keep the building cool in summer and warm in winter. The hotel did not build a parking garage — instead, it uses existing lots in the area for valet parking and encourages public transit for guests.”
Its biggest drawback is its lack of renewable energy. One of the biggest challenges for hotels is allotting valuable space to sustainable measures. In the battle between commerce and commitment, the winner is nearly always predetermined. It would be an economic risk for new hotels to bypass profitable roof decks in favor of photovoltaic arrays (which, it should be noted, also produce carbon through their manufacture). That financial equation automatically means shifting carbon reduction to patchwork strategies such as those used by the Populus.
In the end, the Populus is a distinguished building imbued with good intentions and, at the very least, rises above inaction. Trying to decrease carbon emissions should be the goal of all architects, since eliminating them entirely is more fantasy than reality; pretending otherwise only leads to marketing overreach and its accompanying buzzwords.