A Ryan Cos. US Inc. team has created a plan to turn a proposed 17-story office tower near U.S. Bank Stadium in downtown Minneapolis into a nearly net-zero energy building.
The first renderings of the tower were released two years ago, and the Ryan team worked off that concept while devising a net-zero plan for the site at 728 Fourth St. S. The property today is a slender slice of grass slightly northeast of the stadium in front of Mills Fleet Farm Parking Garage, 740 S. Fourth St.
Ryan has no immediate plans to construct the high-performance building on the site, which is dubbed Block One. The concept was instead an exercise to determine the feasibility of creating a net-zero Class A property in a dense urban environment.
For now, the net-zero building is an idea, not a reality.
Net-zero has become the holy grail of architecture and energy efficiency as clients, states and cities seek to drastically reduce carbon emissions in a global effort to combat climate change. Buildings produce about 40 percent of carbon emissions globally, a figure that could drop with greater efficiency, design and on-site energy generation.
While the Twin Cities are home to many sustainable buildings, no office property is net-zero and no developer has attempted it, although plenty of interest exists among architects and sustainability advocates.
Ryan has marketed the site, though not the concept building, said Tony Barranco, vice president of development. The project was about investigating net-zero. “We learned a lot by doing it,” he said. “Applying the concept to a physical space is such a better way to evaluate [net-zero].”
Ryan assigned a team of young architects to create scenarios for the Block One property in its Downtown East project, anchored by the new Wells Fargo campus. Eric Morin, Ryan’s director of industrial architecture, said the company wanted his team to answer the following question: “Can you build a market-rate net-zero building?”
As it turns out, the answer is close, closer than Ryan figured, though the price tag is much higher than an average Class A office building.
The team included Kaitlin Veenstra and project manager Nate Day, who with Morin presented their findings at a U.S. Green Building Council luncheon meeting July 31 at the downtown Minneapolis office of architecture company HGA. Their work offers a glimpse at the strategies, costs and potential stumbling blocks of getting to net-zero.
Ryan has plenty of experience designing and building energy-efficient buildings, said Veenstra. The Wells Fargo offices — at 550 and 600 South Fourth St. — are the largest project in Minnesota to receive platinum LEED (Leadership in Energy and Environmental Design) certification from the USGBC.
A big driver of that, she said, was the bank itself, which wanted the 1.1 million-square-foot office to use substantially less energy and water and emit fewer greenhouse gases than a typical building of the same size, she said.
Ryan has one net-zero building in its portfolio, the 12,000-square-foot Indian Creek Nature Center in Cedar Rapids, Iowa. Achieving net-zero for a nature center isn’t comparable to a large commercial building, Veenstra said, because the scale and use are so different.
Where a net-zero building should be located was an earlier consideration. A large suburban site offered a chance for geothermal heating and cooling, for example. Because net-zero would cost more than traditional construction, the team opted for a downtown Class A downtown building. “We had to go where the rents are the highest in town,” said Morin.
The team employed “energy-use intensity,” or EUI, a common measurement in sustainability field. Net-zero would be zero EUI.
Building Block One efficiently would result in an EUI of 47.3, Veenstra said, compared with Wells Fargo’s EUI of 39. Adding more energy-efficient materials, solar panels to the adjacent parking garage’s roof and to the building brought the team much closer to its goal.
Employing photovoltaic glass on some parts of the building added a bit more on-site energy, Veenstra said, though less than solar panels. For cooling, a chilled beam system offered greater efficiency than other approaches but at a higher cost, she said. Heating would come from a downtown district energy system.
With solar, the chiller, district energy and high-efficiency design, the building reached 9.6 EUI. Such a low score is termed by sustainability advocates as a “deep green” or “ultra-low energy” project, Day said. Yet the team’s bosses pointed out that a 9.6 EUI isn’t net-zero, so they went back the drawing board one more time.
This time they tried an entirely different tactic. Team members first considered how much on-site energy would be needed to power the building. With that constriction the project took a haircut to reach net-zero, becoming seven stories and 160,000 square feet.
A smaller building would likely need to have a corporate buyer and not serve a multitenant base. The buyer would have to have aggressive energy-efficiency goals and a willingness to pay more for bragging rights to a net-zero building, Morin said.
Achieving net-zero increased the construction cost by nearly $200 a square foot, he said. Lease costs would be $10 more per square foot than other options, although that difference could drop to $4 per square foot with incentives, he suggested.
In both scenarios the energy efficiency of Block One would decline if a data center or data rooms were going to be used by clients. The devices and the equipment offices now use hinder efforts to reduce energy consumption, even in highly efficient buildings.
The team felt that the 17-story, 468,000 square foot glass box could come close to net-zero. If ever built, it would be significantly larger than the most famous net-zero office in the world, the Bullitt Center in Seattle.
At that size the project in the end made the most financial sense even if it didn’t achieve perfect net-zero. It matched or exceeded the sustainably of other net-zero-style office buildings in the country, Morin said. And the designs did not feature any untried strategies or equipment, with even photovoltaic glass having a track record.
Barranco said the study revealed that no matter how energy-efficient a building is, net-zero requires on-site generation.
“The on-site production of energy becomes a critical factor, and that’s the hardest thing to control,” he said. “But we also learned how design can positively impact sustainability.”
Ryan continues to pursue a partner for a deep green structure, Morin added. “Ryan Companies remains committed to staying at the forefront of sustainability and carrying forward the lessons of this study while trying to find the right partners to someday move forward on a project,” he said.
Frank Jossi / Finance and Commerce