What if we just have a little green area on our rooftop? Is there a minimum amount of landscaped area to earn the prerequisite and credit?

There is no minimum landscape area to earn the prerequisite or the credit.

One could argue that this discourages landscaping, but according to USGBC, hardscapes are addressed and, one could argue, discouraged by other credits, so this is considered a fair approach. 

The EPA WaterSense methodology and calculator allows only certain types of irrigation to be assigned to certain vegetation types. Why is this and won’t it skew results?

The type of irrigation that can be assigned to certain vegetation types is pre-determined in the calculator, limiting user ability to make adjustments that might better reflect the design conditions. This is likely based on EPA’s assumptions about potential changes to the irrigation system and future use.

Does the LEED-ND site have to be certified, or can it be in the process of certification?

The site must be certified to achieve this credit. However, LEED v4 ND Plan is an acceptable certification for achieving this credit. The LEED for Neighborhood Development Pilot and LEED 2009 ND Stage 2 and Stage 3 certifications are also acceptable. Note that the LEED v4 ND Plan certification is available to neighborhood-scale projects that are currently in any phase of planning and design, and up to 75% constructed. 

Can we earn Option 2 by adopting a phase-out plan of our old filters and replacing them with MERV 13 filters?

No, in order to earn the credit, all of the filters must be replaced with MERV 13 filters prior to the performance period. Additionally, teams must provide documentation confirming that filters were maintained and/or replaced during the performance period according to the manufacturer’s recommendations.

Is it possible to apply estimated energy consumption for a portion of the building or performance period?

Estimated energy consumption may not be applied under any circumstances. If you don’t have access to energy data or if your project isn’t metered, you must find a solution to track that data prior to the start of the 12-month performance period for this credit.