Thu, 25 Feb 2010 11:16:22 +0000

 A developer decides to build a 320,000 square foot office building that’s 8 stories high with a land footprint of 200 feet by 200 feet, or 0.92 acres. According to area zoning regulations, 3 parking spaces are required for each 1000 square feet of office space. Therefore he must also supply a 960 car parking structure adjacent to his office building, since he doesn’t own enough land to construct a surface parking lot of that size. He hires a parking structure designer and instructs him to give him the most efficient design possible. The resulting design is six stories tall, with160 parking spaces on each floor. The garage features one-way traffic, with cars parked at a 75 degree angle. It occupies a land footprint of 200 by 225 feet, or 1.04 acres, slightly more acreage than the developer’s office building. A big negative – some drivers will have to spiral up six floors to a parking space.

 The year 2000 criterion for the design of such a self-park parking structure is to plan for an 85th percentile vehicle size, which is 17 feet one inch long by 6 feet 7 inches wide by 7 feet high – think a large SUV, like the Ford Expedition. The basic amount of space required to park this SUV is enlarged to allow the vehicle to get into and out of parking spaces, plus door opening room for passenger entrances and exits. So the planned parking space size must expand to 8 feet 9 inches wide by 21 feet 6 inches long. The allotted overhead space is increased by another 4 inches above vehicle height, to 7 feet, 4 inches, giving sufficient head clearance for tall passengers. With room for overhead support beams and the concrete floors, total floor to floor height becomes a minimum of 10 feet. (The floor height in some garages is intentionally increased further, to 11, 12, or 13 feet to achieve a feeling of adequate spaciousness for targeted parking garage users). Since drivers and passengers will be walking around inside, the parking garage must also include lighting systems, stairs, elevators and, possibly, some means of security monitoring.

 To measure the efficiency of the developer’s design, the 288,000 square feet total area of the six floors is divided by the 960 parking spaces, yielding a calculated efficiency of 282 square feet per car. On a volumetric efficiency basis, that area is multiplied by the floor to floor height and divided by the same 960 car number, yielding 2,880 cubic feet per car.

Parking structures comparable to this one cost about $13,000 per space to build in a suburban area and $29,000 per space in urban areas. So the total cost to build the developer’s 960 car garage would range from $12.5 million to $27.8 million, exclusive of land cost.

If you had to drive all the way to the top, to the last parking space, you would have to drive about 1000 feet on each floor and go up all six floors. Your car would cover a distance of over a mile, without any extra distance assumed for floor to floor ramps. At an average speed of 10 mph, plus some slowing or stopping en route because of other cars entering or exiting spaces, the drive might average about ten minutes or so each way for inbound and outbound trips.

The maximum walking distance from a corner of the structure would be 400 feet, taking 2 minutes, at an assumed walking speed of 4 feet per second. Added to that time would be elevator wait time (usually targeted to be 30 seconds or less) and elevator travel time plus your vehicle exiting time. Your total time spent inside the garage could fall in the range of maybe three or four minutes to about 15 minutes.

For users driving smaller vehicles, the massiveness of the overall garage is such a waste of space – with no discount for the user’s compact vehicle taking up much less space.

 itsparker

Taylor stated, "The competition was designed to highlight the best of the best, but to also have this catalog." She refers to the catalog printed by the DOE including the winners and representing products that have now been independently evaluated by experts. Referring to the competition, Taylor pointed out that the catalog essentially labels winners as "recommended by the judging panel."

The entry process was laborious. Companies had to submit extensive documentation including data sheets on enabling components such as LEDs, and drivers. They had to submit photometric files including LM-79 test reports. And the companies had to submit two product samples – one that the judging panel could install for consideration and the second for tabletop evaluation.

The start of the 2010 competition is just around the corner. Expect details at the LightFair International show scheduled for May 10, 14 in Las Vegas.