St. Paul Port Authority unveils 'net zero' warehouse prototype

As the world deals with the effects of air pollution and climate change, many would be surprised to discover that more carbon dioxide emissions in the United States come from buildings than cars and other vehicles.

The building sector is responsible for nearly half (44.6 percent) of carbon dioxide emissions in the country, according to nonprofit Architecture 2030. Transportation amounts to 34.3 percent.

"It's a problem," Monte Hilleman, senior vice president of real estate redevelopment for the St. Paul Port Authority, said at a presentation last week to commercial real estate professionals in St. Paul. "It's a problem for all of us. … We will not solve irreversible climate change without addressing our built environment."

The St. Paul Port Authority unveiled a new "net zero energy" commercial building prototype that its leaders said it hoped would be the future of development in Minnesota and a step in the right direction to reduce local buildings' energy consumption and greenhouse gas emissions.

The Port Authority commissioned LHB engineering and architecture firm to help come up with the design.

A "net zero" structure is one that balances energy used with energy produced through on-site renewable sources. As of this year, there are only about 70 verified net zero buildings in the U.S.

Net zero buildings are also built to yield long-run savings in energy costs for their owners.

Researchers have analyzed what would be the features of a newly constructed, 60,000-square-foot, net zero industrial building. The building would be 80 percent warehouse with the rest functioning as office space.

Whereas most warehouses have an EUI (energy use intensity, or energy use per square foot) of around 36, researchers were trying to get the prototype's EUI down to 14.

The HVAC system could have the single greatest effect on energy use by using a geothermal heat pump system instead of a conventional forced-air heating system. Generally, a more efficient HVAC system could reduce a building's energy use by as much as 38 EUI and save about $18,000 a year.

The prototype also includes a super-insulated roof and walls, more windows to allow for more natural light (with southern exposure) so that the building could use daylight dimming sensors and save electricity, and sealing around doors and windows.

Solar panels would need to be installed over at least 32 percent of the flat roof to offset the targeted 14 EUI. The building would cost about $4.5 million to construct.

The St. Paul Port Authority will continue to educate potential partners about the prototype.

"We are trying to find the right business, the right contractor that wants to do this with us," Hilleman said.