The landscape architect provides LEED documentation for submittal to LEED Online.

The landscape architect runs final outdoor water use calculations for the project’s design case annual water usage. These calculations should confirm that the landscape water reduction goals are met. If the goals are not met, adjust the landscape and irrigation design as needed.

LEED for Schools projects can decide to exclude playing fields from the landscape calculation. However, the playing fields must then be excluded from all LEED calculations, including open space requirements. If such areas are included, they must be included in all other applicable Water Efficiency credit calculations (unless otherwise noted).

The landscape architect develops a baseline outdoor-water-use calculation based on mid-summer (July) and compares that to a calculation for the planned project design case water use (also for July). The difference is the percent reduction and identifies credit achievement.

Perform LEED calculations to evaluate compliance. Only “softscape” areas are included in calculations. Projects that replace landscape irrigation with hardscape to reduce irrigation needs cannot count this area in their calculations.Use the calculator provided in the LEED Online credit form to evaluate compliance.

The mechanical engineer calculates the potential for graywater reuse and applicable treatment methods.

There are fewer codes and associated costs for collecting and using rainwater for irrigation than for interior water reuse. Harvested rainwater can often be reused for irrigation purposes with minimal treatment, although filtration is usually needed.

The landscape architect calculates the potential for rainwater reuse and corresponding cistern sizes to accommodate landscape and other rainwater reuse applications. Calculations must account for annual rainfall of the project location.

The design cost of a drip irrigation system is generally comparable to a standard system. However, installation might be more expensive for drip irrigation, particularly as plant density increases.

Detailed calculations to demonstrate irrigation efficiency will be required from the landscape architect. The study “Performance and Water Conservation Potential of Multi-Stream, Multi-Trajectory Rotating Sprinklers for Landscape Irrigation” (see Resources) provides expected water conservation percentages derived from measured data. Efficiency ratings provided by manufacturers for irrigation components and controls can be used for calculations, but most manufacturers do not provide this data, so you’ll need additional calculations.