The calculations were figured by LAndscape COnsultant and PA; The key to this credit is how the "Baseline Case" is determined. The "Design Case" takes into account the fact that the species planted are native and respond well to the Houston environment. The "Baseline Case" was calculated using a different turf grass species which would cover the entire landscaped area and would not be shaded by trees. We feel like this credit might be "on the fence" our team is a bit unsure of how to determine the subjective factors of the equation. For example, according to the Reference Guide, "If a species does not require irrigation once it is established, then the effective [Species Factor] = 0 and the resulting [Landscape Coefficient] = 0." Eventually, it will be possible to turn off this design\'\'s irrigation system once the plants are established, but should that be considered in the calculation if it takes longer than 1 year? What is the cut-off: 3 years, 5 years, 10 years?
Although the project can take credit for selection of a native or drought tolerant species mix in the LEED calculator, the planting types should approximately correspond in both the baseline and the proposed strategy. That is, it is unreasonable to assume that the baseline is 100% turfgrass when the project clearly intends to include trees, shrubs, and planting beds. Irrigation efficiency is calculated on water delivered in the month of July of a typical year. With respect to LEED, the intention to eventually \'turn off\' an installed irrigation system is not the same installing an efficient irrigation system. Irrigation efficiency is also dependent on the type of irrigation system used. Drip irrigation or other low-flow systems can be used to achieve this credit, alone or in combination with appropriate species selection. It is up to the landscape designer to provide documentation that the species selected will not requre permanent irrigation once established. The generally accepted timeframe for temporary irrigation is one to two years. Applicable internationally.