The LEED-NC v2.2 requirements is for no more than 12 months. According to a LEED Reference Guide addendum from 7/19/2010, the time period was been increased from 12 months to 18 months for LEED 2009 projects, but USGBC has not altered the timeframe for pre-2009 projects.
Although this may contribute to reducing irrigation demand, this does not help with achieving the credit, as landscaped area in the both the baseline and design case has to be the same. Although decreasing vegetated space may be a sensible option for some projects, it is not allowed to contribute to this credit. It would not match the intent of this and other credits for LEED to include an incentive to reduce vegetated area.
No. LEED defines the scope of the credit as landscaping outside of the building footprint.
Yes, if it is irrigated and not considered in its natural state.
For any project, the minimum is 5% of site area. This can include planters.
The baseline and design cases are the same, and they are based on the total irrigated area in the design case.
No. This approach has been rejected by LEED reviewers, who state that these are potential sources of potable water and their use does not meet the credit intent. The LEED Reference Guide makes reference to groundwater in specifically allowing use of nuisance water that needs to be pumped away from the building—but other groundwater is not mentioned as compliant.
No, non-potable groundwater used for irrigation (other than nuisance groundwater, i.e. water pumped away from a foundation) is considered a potential potable source and would not count towards earning this credit. GBCI has upheld this rule even in cases where the local groundwater has mineral or other content that requires treatment before it can be potable.
Advertising and directional signage, as explained in Addendum i of ASHRAE 90.1-2007, and further defined in the Users Manual for ASHRAE 90.1-2007, is exempt. Essentially, that means that internally illuminated advertising signs are exempt, but those illuminated by lighting that is not ‘integral’ to the signage itself must be included in the calculations.