Design landscape features to avoid invasive species and minimize demand for water and synthetic chemicals.
2.1 No Invasive Plants. Introduce no invasive plant species into the landscape.
Note: Invasive plant species vary by region. Consult the local Cooperative Extension Service or state agencies. A list of regional resources is available from the U.S. Department of Agriculture, at www.invasivespeciesinfo.gov/unitedstates/state.shtml. Not all nonnative species are considered invasive.
Note: Points shown below are for buildings that are fully landscaped. A project that has not completed the designed landscaping may earn up to 50% of the points for each credit as long as 50% or more of the designed landscaping is completed upon certification. In this case, 100% completion of the landscaping must be required by homeowner association or other rules within a specific time period not to exceed one year after occupancy. Erosion controls and soil stabilization measures must be robust enough to be effective for one year. The builder or project team must also develop a landscaping plan that meets the requirements in SS 2 and provide it to the homeowner.
2.2 Basic landscape design (1 point). Meet the following requirements for all designed landscape softscapes:
- Any turf must be drought-tolerant.
- Do not use turf in densely shaded areas.
- Do not use turf in areas with a slope of 25% (i.e., 4:1 slope).
- Add mulch or soil amendments as appropriate.
Mulch is defined as a covering placed around plants to reduce erosion and water loss and to help regulate soil temperature. In addition, upon decomposition, organic mulches serve as soil amendments. The type of mulch selected can affect soil pH.
- All compacted soil (e.g., from construction vehicles) must be tilled to at least 6 inches.”
2.3 Limit conventional turf for mid-rise (maximum 2 points, as specified in Table 2). Limit the use of conventional turf in the designed landscape softscapes.
2.4 Drought-tolerant plants for mid-rise (1 point). Install drought-tolerant plants. Both points must be earned under SS 2.3 in order to earn this credit. Install drought-tolerant plants such that at least 90% of the installed plants are drought-tolerant.
2.5 Reduce overall irrigation demand by at Least 20% for mid-rise (maximum 3 points, as specified in Table 3). Design the landscape and irrigation system to reduce overall irrigation water usage. The estimates must be calculated and prepared by a landscape professional, biologist, or other qualified professional using the method outlined below.
|Table 2. Limited conventional turf|
|Percentage of designed landscape softscape area that is conventional turf||Points|
|20% or less||2|
|Table 3. Reduction in water demand|
|Reduction in estimated irrigation water usage||SS 2.5 points||WE 2.2 points||Total points|
|60% or more||3||2||5|
Method for calculating reduction in irrigation demand
Calculate the baseline irrigation water usage:
Baseline Usage = Landscaped Area * ET0 * 0.62
where ET0 = Baseline Evapotranspiration Rate (available from local and state Departments of Agriculture)
Calculate the design case irrigation water usage:
Design Case Usage = (Landscaped Area * ETL ÷ IE) * CF * 0.62
where ETL = ET0 * KL and KL = KS * KMC . Refer to Tables 4 and 5 for values for KS and KMC, and to Table 6 for values for IE. For CF, use estimated value based on manufacturer’s specifications for percentage water savings.
Calculate the percentage reduction in irrigation water usage:
Percentage Reduction = (1 – Design Case Usage ÷ Baseline Usage) * 100
Refer to Table 3, above, to determine points earned.
|Table 4. Species factor|
|Vegetation type||Species factor (Ks)|
|Table 5. Microclimate Factor|
|Example microclimate impacts||Species factor (KMC)|
|High sun exposure||1.0||1.2||1.5|
|Protection from wind||0.8||0.9||1.0|
|Table 6. Irrigation Efficiency|
|Irrigation type||Irrigation efficiency (IE)|
|Impact and microspray||0.5||0.7|
|Low volume and point source (e.g., drip)||0.7||0.9|