I've been working on documentation for SSc4.3 Alternative Transportation - Low Emitting and Fuel Efficient Vehicles and SSc4.4 Alternative Transportation - Parking Capacity. We're providing less parking than is typically required and providing preferred parking for both carpoolers (5% of all spaces) and Low-Emitting Vehicles (LEVs - another 5% of all spaces) for total of 10% required preferred parking.
Must have been a slow ride
In our project, 10% of total parking spaces is over 200 spots, as this is an enormous building. In the interest of reducing costs, I decided on a strategy where we would group the two preferred options together and simply designate the closest 10% of the parking to both LEV and carpoolers, thus allowing the spaces to fill up in a more efficient manner than if we separated the two into parking clusters. In addition to that, instead of buying and installing 200 signs I proposed that we just stripe the preferred spaces in a different color and have a explanation sign posted at each entrance to the lot. We need paint stripes anyway, and it seems incredibly wasteful to use materials to create 200+ signs saying the exact same thing.
Everything was going fine until our contractor wanted to know whether this had been done before and whether I'm sure we're allowed to mix the spots... Damn his entirely reasonable questions!!! You can probably guess the answers, so I browsed through the reference guide (didn't find the answer), then the Harvard files (they cover a lot of multiple building issues, but not this one), and finally the credit interpretation rulings (CIRs) and learned a whole bunch of stuff that I thought was worth sharing:
Preferred Parking Discounts
You may have noticed the reference guide indicates that for parking passes can be used in exchange of preferred designated spaces. You may also have noticed that they don't mention how much of a discount is required! Fortunately this has been cleared up in a LEED-NCv2.2 CIR dated 07/05/2007:
In order to establish a meaningful incentive in all potential markets, the parking rate must be discounted at least 20%. This approach is acceptable as long as the discounted rate is available for all customers (not limited to the number of customers equal to 5% of the vehicle parking capacity) and publicly posted at the entrance to the parking deck.
Defining "Low-Emitting Vehicles"
The reference guide indicates that anything with a score of 40 or higher on the American Council for an Energy-Efficient Economy vehicle ratings. The fine folks at Harvard pointed out that these ratings don't come out until some time after a vehicle is released and suggested an alternate standard be available. As a result, you can also use the EPA's SmartWay Elite certification in it's place. This was confirmed in a LEED-NCv2.1 CIR dated 10/02/06. The vehicle must be rated as "SmartWay Elite" and not just "SmartWay". Using this database has the added benefit of being completely free, as opposed to the ACEEE database which requires a subscription. I'm not sure if one is more stringent than the other.
A number of requests for using a high MPG rating (say 35 mpg or above) were DENIED by the review committee, so don't plan on making that argument stick. The reasoning is there is a consideration for the life-cycle emissions of production of the car and not all MPG are created equal with regard to emissions (the classic example being that 2-stroke engines are much dirtier than 4-stroke).
At the end of the day I never did get an answer to the questions about combining and sharing parking spaces for LEV and carpool users, or about the striping and signage. This could be due to the fact that the benefits are so obvious it wasn't deemed necessary to state, but I'd really like to have confirmation. If one of you have tried this and it was accepted please share with all of us by leaving a comment!