Sustainable: A triple LEED for Mall of America

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When architects and planners first began designing the Mall of America’s new retail, office and hotel complex, they found clients who wanted to make the three joined buildings energy-efficient enough to achieve certification from the United States Green Building Council.

Part of the reason was that the Bloomington megamall’s Canadian owner, Triple Five Worldwide, had been running a pretty efficient operation for many years yet had received barely any recognition for the effort.

By having three buildings achieve LEED — Leadership in Energy and Environmental Design — certification, the MOA’s ownership could better showcase its concern for the environment, said Phil Stien, senior associate architect with Minneapolis-based DLR Group.

The $325 million addition includes the 342-room, 14-story JW Marriott Minneapolis Mall of America hotel, a product of a partnership of mall owner Triple Five Worldwide, the Prior Lake-based Shakopee Mdewakanton Sioux Community and Golden Valley-based Mortenson Development, which built the DLR Group-designed additions. The second building is a 165,000-square-foot retail space with a parking garage. The third structure is the 180,000-square-foot, 10-story office tower.

The reason the three buildings had to be certificated separately, despite the fact they flow together, is that they have distinctive uses and serve different functions, Stien said. The hotel had to be a full “Building Design & Construction” LEED project because the interiors were finished, he said. Conversely, the retail section and office building had to be “Core & Shell” because their owners had no control over how the interiors would be built out, Stien added.

The mall’s sustainability ethos may come even as a surprise to many visitors who have little idea of its huge recycling program, recent investment in lighting and other efforts. Nathan Klutz, the mall’s construction director, pointed out that a recent project to install LED lights in the complex’s parking structures was the largest such bulb replacement project in the nation.

The move saves $500,000 annually in energy costs and has a return on investment of four to five years, he said. The mall offsets energy used in the Nickelodeon Universe and the two parking garages with Windsource credits purchased from Xcel Energy.

Efficient toilets save 1.4 million gallons of water a year. The mall has no central heating system, instead using passive solar warmth from skyways along with heat from store fixtures and visitors — yes, body heat — to help maintain a steady 70-degree temperature, he said. More than 60 percent of the trash is recycled or sold, Klutz noted.

The project may be without precedent in Minnesota. “I think it’s pretty unique for Minnesota. There are a few organizations that have done two [at the same time], but doing three is unique,” said Sheri Brezinka, executive director of the state chapter of the Green Building Council. “It shows real leadership by the mall and shows its commitment to sustainability in a very public way.”

Amassing points

LEED certification is a point-based system. Depending on the total number of points, a project can be just “certified” or go for higher levels — silver, gold and platinum. The desire was to simply get the buildings certified at the base level, said Stien, rather than reach for higher levels. The projects first had to get an exemption from the USGBC, which requires LEED additions to be a minimum of 20 percent larger than the original building.

Despite the hefty size of the addition, it does not fit the 20 percent rule because the mall has more than 4.2 million square feet of space, he said. The reason for the regulation, Stien noted, was that buildings could tack on a smaller structure and call themselves LEED, even if it only reflected a certification of a sliver of the overall structure.

DLR Group won some easy points, in particular for site selection, development density and community connectivity. Having built resources nearby — namely the mall’s vast infrastructure — helps tremendously.

“You don’t have to build a bunch of other construction to support new construction,” Stien said. “This spot was ideal.”

The mall has one of the busiest mass transit hubs in the state, he pointed out, another advantage that simply solidified the full six points the alternative transportation category offers. Moreover, the mall’s website directs people to light rail and bus stations so they can reach the shopping mecca via public transit.

In planning for more points, the architects opted for a white roof, which allows equipment to operate without the same heat island effect of a darker covering, he said. Water use was another point builder. DLR Group senior associate Shona O’Dea explained how low-flow fixtures in each building scored at least a 35 percent reduction from standard equipment.

Energy was saved, too.  Less water means less water to heat, she said. Adding LED lighting, an improved building envelope and efficient heating and cooling systems led to a 22 percent energy savings when compared with a conventional project, O’Dea said. That measure alone offered more LEED points than many of the categories.

Other efforts of the mall team included:

• Measuring and verifying the results of LEED approaches through Energy Star Manager.
• Diverting 75 percent of construction waste from landfills.
• Covering materials, especially absorbent ones, during construction to reduce indoor air quality problems and improve occupant well-being.
• Using low emitting materials, solvents and paints.
• Providing “thermal comfort” according to nationally accepted guidelines.
• Using lightbulbs with minimal levels of mercury.
• Employing LEED as a teaching tool within the building in an ongoing campaign.
• Creating sub-metering option for tenants in retail and office buildings.

The project also resulted in two booklets being created by the team. One was for future tenants who may want to get LEED certification for commercial interiors. Those tenants will get plenty of points just for being in a LEED building, he pointed out, if they choose to certify. A second booklet is a brochure that explains to the public how the buildings achieved LEED and what sustainable aspects they have, he said.

The hotel, retail and office tower collectively make up the largest LEED project Stien has worked on. But next up is yet another expansion, called “Collections at the Mall of America,” that will have a hotel, office and high-end retail. The aim there, Stien said, is to continue the mall’s efforts to build energy-efficient, sustainable buildings.