Water Efficient Landscaping

Water efficient landscaping is planting and developing outdoor space such that it limits or eliminates the use of potable water for maintenance. A building can use up to one third of its drinking water for outdoor irrigation. LEED rewards projects that reduce potable water use for irrigation through conservation or by using non-potable water.
Credit: CIAT International Center for Tropical Agriculture

According to the U.S. Environmental Protection Agency, outdoor water use makes up one-third of residential water use, or approximately 9 billion gallons of water per day.  About 50% of this water is wasted because of inefficient watering methods and irrigation systems.  In a commercial setting, outdoor water use can make up 5 to 30 percent of the building’s water use.

In most cases, the water used for irrigation is potable drinking water.  By using this water for irrigation, people are requiring municipal water supply systems to use more energy to treat large amounts of water.  While water is technically recycled through natural processes, water can take a long time to be returned to the groundwater system, so water suppliers can struggle with meeting demand.  

There are two ways to address this problem: water conservation through reduced irrigation and non-potable water reuse.  Projects can strategically plant drought-resistant plants or arrange them such that less water will not be wasted when they are watered.  Projects can also install water efficient irrigation systems, such as drip irrigation or weather-sensing systems that use less water than traditional irrigation methods.  Alternatively, a project can use recycled graywater or blackwater, captured rainwater, or treated wastewater to irrigate plants.  A project can also choose to use both strategies and reduce the water needed for irrigation, and then use non-potable irrigation for the rest of the property’s needs.

LEED 2009 and Water Efficient Landscaping

LEED 2009 rewards projects that reduce their potable water use for irrigation through these methods.  Water Efficient Landscaping, Water Efficiency Credit 1, awards projects two to four points, depending on how much outdoor water use reduction they achieve.  The credit requirements are as follows:

Option 1: Reduce by 50% (2 points)

Reduce potable water use for irrigation by 50%.  The potable water for irrigation can be reduced by using more efficient irrigation systems, captured rainwater, recycled wastewater, or non-potable water that has been treated by a public agency.  It can also reduce potable water use by changing any one of the factors in this equation:

KL  =    Ks    x   KD  x   KMC                         

KL  = Landscape coefficient, volume of water lost via evapotranspiration

Ks  = Plant species factor

KD  = Plant density factor

KMC  = Microclimate factor

 

Option 2: No potable water use or irrigation (4 points)

Meet the requirements for the first option, but reduce potable water use for irrigation by 100%.  There are two paths for achieving this credit:

Path 1: For irrigation, use only captured rainwater, recycled wastewater or non-potable water treated by a public agency.

Path 2: Install landscaping that does not require permanent irrigation systems.  Temporary systems are allowed for the first 18 months if used to establish plant growth.

Free LEED GA Practice ExamStrategies for Water Efficient Landscaping and LEED

In LEED, Water Efficiency Credit 1, Water Efficient Landscaping addresses potable water for irrigating landscapes. In BD+C rating systems, projects can reduce potable water use by 50% for 3 points, and by 100% for 4 points.

The following are examples of strategies that you can use to green your garden - and garner LEED points in the process.

1. Low Maintenance Grass Seed

Low maintenance grass seed requires very little or no water or upkeep from mowing or landscaping. Much of the United States uses bluegrass, which requires a great deal of water. The Environmental Protection Agency estimates that watering grass accounts for one-third of our water use, so using low maintenance species or turf can increase water efficiency for landscaping.
Certain species of grass are more drought-tolerant than others. Recommended species for areas with little rainfall are: St. Augustine, Zoysia, Bermuda, Buffalo, Bahia, Fescues, and Centipede.

Pearl's Premium is an example of low maintenance and drought-tolerant grass seed that is made from a blend of five native or adapted fescues. This grass, which is not genetically modified, comes in Sunny, Shady or Sun-Shade blends, which are based on the grass’ light exposure. It requires little or no water, fertilizer, or treatments, but may use organic fertilizer or compost one or twice a year, if needed.

2. Smart Irrigation

Smart irrigation systems automatically adjust the amount of water for landscaping either according to the user’s scheduling or by sensing a variety of external factors, such as the weather, amount of sunlight, species of plants and soil type.

Hydropoint's WeatherTRAK Smart Sprinkler Evapotranspiration (ET) Controller is an example of a smart irrigation system, and is show to reduce water use for landscaping by up to 59% and the amount of runoff pollution by up to 79%. It uses satellite technology to track the temperature and weather, and adjusts the amount of water accordingly.

3. Eco-Friendly, Recycled Mulch

Mulch can reduce water use for landscaping because it retains water and reduces evaporation. For sustainability reasons, it is a good idea to choose eco-friendly mulch, perhaps made from recycled materials, because it is responsibly sourced and have a smaller impact on the environment.

For example, Nu-Wool produces Hydrogreen Hydroseeding Mulch, which is made from 100% post-consumer recycled paper. It is biodegradable and made with organic dyes, and contain a natural wetting agent that helps it absorb water more readily. They also offer HydroGreen Plus, which is made from half recycled paper and half wood fiber. This makes it stronger, less prone to erosion and better for germination than the original Hydrogreen.

4. Xeriscaping

Xeriscaping is the use of plants that are drought-resistant and adapted to dry climates for the purpose of reducing water use in landscaping (which also saves time and money for labor). Planting with drought-tolerant, low maintenance grass, as described above, is a type of xeriscaping. Other types of plants used for xeriscaping include cacti and agave.

5. Drip Irrigation

Drip irrigation is the process of watering and/or delivering nutrients to plants directly at the roots, which saves water.

For example, Green King's Deep Drip Tree Watering Stakes are shown to save between 20 and 70% water by watering, fertilizing and aerating trees, shrubs, bushes and other plants directly at the roots. They help to build deeper root systems, which avoids soil erosion and root exposure.

Deep Drip stakes, which are made with ABS plastic, can be installed when the plant is first planted, or around an existing tree or bush. A standard hose can be attached to the stakes to water the plant.

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