When the U.S. Green Building Council gave out its first LEED rating for a "green parking structure" last year, the blogging world ignited. It did seem like a bit of a contradiction, and it posed an important question: If the automobile, with its associated fossil fuel emissions, is the root of all environmental evil, can a parking structure really ever be considered green?

A parking structure implies more driving and more emissions, and from the perspective of the urban planner, it hogs valuable land that could otherwise be used for commercial, retail or public purposes. As David of the Good Human blog opined, "... a parking garage cannot be green, even if it was made from site-grown bamboo and ventilated by flapping butterfly wings."

But when I was approached to do a story about PerfectPark, the newly introduced (to the U.S.) robotic parking system from Italy, I started to believe in a green parking utopia. The system was invented by Trevi, Europe's leading civil engineering firm  — the same guys who fixed the leaning tower of Pisa — in order to deal with massive and unbearable congestion problems common in cities like Rome and Stockholm, where tiny streets and historic buildings make high-density parking a near impossibility, and gridlock an ever-present reality.

The Trevi system is ingenious. One big silo, 72' across, is dug up to 9 levels deep with clearances of 18" to the side of a building, allowing it to be located in the most cramped of urban environments. A rotating mechanical platform is installed inside the silo which acts like a robotic valet, taking your car underground and shelving it in one of 108 slots. When you watch the video, it looks unbelievably high-tech, but in fact the system has been around for over 17 years with 20 installed and 30 planned systems throughout Europe. And the failure rate is essentially zero.

David Mitchell, who's company MitchCo, Inc. holds the sole license in the U.S. and Canada for the parking system, explains the value offered by this parking system:

With PerfectPark, you can take existing surface parking, bury it underground and create beautiful park settings above. On a 15,000 square-foot lot, we can install 216 spaces below ground, preserving the land above for public use. Normally, for surface parking, that much parking would take two acres of land.
A before and after scenario in one town in Sweden:

But what really makes the system 'green,' in the tech sense of the word, is the dramatic reduction of resources required to both produce and run the structure, as well as a significant reduction in auto emissions related to parking and exiting time.

Because there is no need for driving lanes inside the structure, the average square foot per space is 220 square foot, about 40 percent less square footage than that required for a typical structure. That means considerably less building materials — about 30 percent less concrete according to an engineer I spoke to at MitchCo, and no structural steel at all (the concrete silo is self-supporting).

Also, because normal parking structures are occupied, the building code requires extensive lighting (120 8' double fluorescent tubes) running 24-7 and accounting for about 50,000 kWh of energy use per year for a typical 216 car structure, plus mechanical ventilation if the structure is underground. The Trevi system requires no lighting or ventilation and has the added bonus of delivering the car at a perfect range of 50-60 degrees, because it is naturally heated/cooled (depending upon the time of the year) by subterranean temperatures.

There is also a significant reduction of auto emissions when you factor in the average in-and-out time of a parking structure in the US — 8.1 minutes according to Parking Today. I did a little math on the auto emissions associated with parking and exiting time:

Assuming a 75 percent occupancy rate for a 216-car garage open peak hours 8-10 (with an average visit of 2 hours), that would mean in a typical day there would be about 1,100 in-and-out round trips. At 8 minutes a pop, that is 150 hours of driving or idling inside the structure per day! Since low speed stop-and-start driving and idling burns gas (one calculation shows about .003 gallons/per minute), that would mean about 27 gallons of gas used by people parking their cars x 365 days that's about 10,000 gallons of gas per year associated with just one 216-car garage.

In contrast, Perfect Park is just like a valet, except when you drive up to the platform you turn your motor off. When you leave the vehicle a security gate closes, and the elevator uses hydraulics to lower the car with almost zero energy. The robotic system then kicks in and rotates the car platform to shelve the vehicle. The retrieval process takes less than a minute. This does take a significant amount of energy, but according to Mitchell the energy requirements of the system are low enough that they can be covered by a solar panel system.

Several cities in California are licking their chops to be the first in the U.S. to have a PerfectPark. For all of the above reasons (and the additional benefits of eliminating exposure to both toxic fumes and physical assaults) MitchCo believes the system could receive up to 14 LEED points for a new construction project, making it attractive for developers and municipalities seeking a LEED rating for their green buildings, and some 'green parking' cache for their downtown renewal projects.

Also on MNN: 

Political Habitat: State and local budgets for parks, environmental protections get the ax.

Robotic valet offers 'green parking' option
PerfectPark brings European technology to the U.S. and reinvents parking as we know it.