In LEEDv3.0 Reference Guide pg.182-183, it says:

"For buildings without vegetation on the grounds, teams can earn points by reducing the use of potable water for watering any roof and courtyard garden space or outdoor planters, provided the planters and garden space cover at least 5% of the building site area (including building footprint, hardscape area, parking footprint, etc.). If the planters and garden space cover less than 5% of the building site area, the project is ineligible for this credit."

So this applies only to projects which does not have any ground available (such as building basements extending to the plot limits etc.), or this requirement applies to even projects where ground space is available. Kindly clarify.

Thanking You.