Page 79 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers

60 Cha pte r T w o

OPTION 1—MIXED USE
For mixed-use buildings with less than 10% commercial floor area adhere to the Case 2
Residential Requirements and for all others adhere to the Case 1 and 2 requirements for the
respective Non-residential and Residential components.
OPTION 2—MIXED USE
Provide no new parking.
NOTES:
“Preferred parking” refers to the parking spots that are closest to the main entrance of the project
(exclusive of spaces designated for handicapped) or parking passes provided at a discounted price.
In LEED 2.2, when parking minimums were not defined by relevant local zoning
requirements, or when there were no local zoning requirements, either of the following
alternative parking calculation methods (A or B) was required. These are not required in
LEED-NC 2009.
A) Meet the requirements of Portland, Oregon, Zoning Code: Title 33, Chapter 33.266
(Parking and Loading)
OR, if this standard is not appropriate for the building type,
B) Install 25% less parking than the building type’s average listed in the Institute of
Transportation Engineers’ Parking Generation study, 3rd Edition.
Potential Technologies and Strategies
Minimize parking lot/garage size. Consider sharing parking facilities with adjacent
buildings. Consider alternatives that will limit the use of single occupancy vehicles.

Calculations and Considerations
The intention of this credit is to reduce the use of SOVs, which has other potential
environmental benefits in addition to those just listed.
Option 1 in Case 1 and Case 2 in LEED 2009 for SSc4.4 require that the total number
of parking spaces (TP) does not exceed the required zoning minimum. Most zoning
codes have a methodology for determining the minimum number of parking spaces that
should be provided for different uses and different size facilities. The submittals should
include the verbiage of the applicable zoning code and the supporting calculations to
determine the minimum parking required by local zoning code. The two options for this
credit mandate that the maximum total parking provided (TP) be equal to or lower than
the minimum as set by the local code, whether the local code has a different maximum
parking calculation or not. (Sometimes the parking allowed can be lower than the
minimum as set in the zoning code, if the project has been granted a variance by the
regulatory authority due to special or exceptional circumstances.) In the past, most
zoning codes did not have a calculation for maximum allowed parking, and the parking
installed would frequently far exceed the zoning minimum. Recently, many zoning
codes have been modified to include both a minimum and a maximum allowable number
of parking spaces, mainly to address the environmental concerns arising from the typical
impervious surfaces that are used to build parking facilities and their impacts on
stormwater runoff and the urban heat island effect. As mentioned in the errata as posted
in the spring of 2007 by the USGBC, there are two alternatives to determining the total
parking allowed if a minimum is not set by local code or zoning. In these cases the total
parking (TP) should not exceed the requirements of the Portland, Oregon, Zoning Code:
Title 33, Chapter 33.266 (Parking and Loading) or, if the Portland, Ore., standard is not
appropriate for the building type, then the total parking should be at least 25 percent less