Green roofs were on developer Kyle Zeppelin’s radar screen long before the initiative to require them on some buildings in Denver surfaced.
The green roof initiative was adopted by Denver voters last month by an 8.6 percent margin. It was widely opposed by Denver’s development community, with Zeppelin being the most high-profile exception.
“Denver developers are used to getting their way,” Zeppelin told me recently over lunch at the Source, one of his developments in RiNo.
“This was truly a David vs. Goliath issue. Opponents outspent us by about an 8-1 margin. And probably 50 cents of every dollar for the green roof side came from us,” Zeppelin added between bites of his chicken sandwich, sans bread.
A crane delivered one of the first trees to the roof of Zeppelin Station’s green roof.
The Denver Metro Commercial Association of Realtors strongly opposed the measure. The initiative requires all commercial buildings constructed after Jan. 1, 2018, that have more than 25,000 square feet to provide at least 20 percent of the roof as green space.
Similar-sized commercial buildings also will be required to have at least 20 percent green space when the roofs are replaced. Solar panels can be used to offset some of the requirement for a green roof.
DMCAR was far from alone in its opposition to the green roof initiative.
Denver Mayor Michael Hancock, the Denver Metro Chamber, the Downtown Denver Partnership, VISIT Denver and the editorial board of the Denver Post all opposed the measure.
Shown is the recently planted green roof on Zeppelin Station.
Zeppelin, whose father, Mickey, was a pioneer developer not only in RiNo but also in LoDo and the Golden Triangle, was an early adopter of green roofs.
“We were looking at ways to improve our tenant experience” aesthetically and environmentally,” Kyle Zeppelin told me.
Zeppelin concluded about two years ago that green roofs could accomplish the goals; his team ran the numbers and they penciled out.
They currently are installing green roofs on three buildings: Flight, Zeppelin Station and the Source Hotel.
“One point. Maybe slightly less,” Zeppelin answered, when I asked him what the additional costs were to incorporate the green roofs into the buildings.
In other words, the roofs added 1 percent or less to the entire construction cost for each building.
Shown is the green roof on Zeppelin Station.
“Developers spend a lot more money on things like granite that don’t add anything to the livability and experience of tenants,” Zeppelin said.
Last spring, when I toured the 140,000-sf Flight office building in Taxi with Zeppelin, he noted, almost in passing, that the building would be home to the second largest green roof in Denver.
“It will be the largest green roof on a commercial real estate building so far,” Zeppelin said. The Flight green roof will have four deciduous trees and 10 varieties of grasses/shrubs and perennials. Flight is anticipated to be a Platinum LEED certified building.
Zeppelin Station will have about four varieties of grasses/perennials, two species of vines to grow down the face of roof terraces and nine deciduous trees on the green roofs. Of the 10,000 sf of roof space on Zeppelin Station, about 3,900 sf will be dedicated to a roof terrace with the integrated green roof.
Only the green roof on top of the Environmental Protection Agency building in downtown Denver, with almost 20,000 sf, is larger.
Advantages of green roofs, also called “living roofs,” or “eco roofs,” according to the EPA include:
- They create a place for stormwater to soak in, reducing the amount of stormwater runoff from a building. The foliage also slows and filters the stormwater that does run off the roof.
- When built in urban areas, green roofs can reduce the Urban Heat Island Effect, which is dangerous to human health, especially at higher elevations such as in Denver. Having enough green roofs in a city can actually reduce the energy expenses of surrounding buildings as the urban temperatures are reduced.
- Region 8 (which includes Colorado) experiences very warm summers and very cold winters. Green roofs reduce energy expenses for buildings by providing insulation to reduce heat loss during the winter and air-conditioned loss during the summer.
- Due to the increased elevation from sea level, buildings in Region 8 are exposed to intense solar radiation, which damages the roof membrane. Green roofs extend roof lifespan by protecting the membrane from sun damage.
- Green roofs can provide habitat for birds, butterflies and insects.
What the EPA didn’t say is that green roofs can also produce food. The green roof on the Source Hotel will primarily be used to grow herbs that will be used in the hotel’s restaurant, Zeppelin said.
A rendering of what the green roof will look like on the Flight building. Source: Dynia Architects.
Zeppelin also noted that green roofs can withstand the monster storms, like the one last May that shredded roofs, causing close to $1.5 billion in damage.
“That is a great example,” said Stephen Dynia, the design architect for the three buildings that will sport green roofs.
“When we had that hail storm, many roofs needed to be replaced, while green roofs lost a few plants,” added Dynia, who worked closely with the landscape architect and the structural engineer on the green roofs on Flight, Zeppelin Station and the Source Hotel.
Previously, Dynia had installed green roofs on homes in Jackson Hole, Wyoming, where the “owners wanted to make their homes blend into the landscape.”
Since commercial buildings already are engineered to withstand weight loads for things like heavy snow, they don’t need to be upgraded very much to hold plants and trees, he said.
“And a green roof lasts two to three times as long as a traditional roof because the waterproofing membranes protect them from the elements,” Dynia explained.
Shown is the green roof on Flight.
Dynia described the new green roof ordinance as “progressive,” and said as more owners and developers install them, the price will drop even more.
“It’s kind of like LEED,” Dynia said. “In the early years, it was very costly to get a building LEED certified. Now, it is a relatively nominal cost” because it has been so well embraced, he said.
It obviously costs more to retrofit an existing building than tp build a green roof from scratch, but that too will change as products are designed to meet more demand, according to Dynia.
“At some point, we will have to replace the roof on our Taxi I building and there will be an added cost to us to replace it with a green roof,” Zeppelin said.
“But even if we didn’t have to, we probably would replace it with a green roof as an amenity to our tenants and as a way to keep an older building relevant.”
