In the paragraph beginning with "Using groundwater...", replace the last sentence with the following:Additionally the credit can be met when landscape irrigation is provided by raw water (excluding naturally occurring surface bodies of water, streams, or rivers, and ground water) that would otherwise be treated specifically for nonpotable uses. Only ponds designed solely for the purposes of stormwater retention or detention can be used for this credit.
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Credit language
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Requirements
OPTION 1: Reduce by 50% (2 points)
Reduce potable water consumption for irrigation by 50% from a calculated midsummer baseline case or using the month with the highest irrigation demand. Reductions must be attributed to any combination of the following items:- Plant species, density and microclimate factor
- Irrigation efficiency
- Use of captured rainwater
- Use of recycled wastewater
- Use of water treated and conveyed by a public agency specifically for nonpotable uses
OR
Option 2: No potable water use or irrigation1 (4 points)
Meet the requirements for Option 1.AND
PATH 1
Use only captured rainwater, recycled wastewater, recycled graywater or water treated and conveyed by a public agency specifically for nonpotable uses for irrigation.OR
PATH 2
Install landscaping that does not require permanent irrigation systems. Temporary irrigation systems used for plant establishment are allowed only if removed within a period not to exceed 18 months of installation.SITES-LEED Equivalency
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.What does it cost?
Cost estimates for this credit
On each BD+C v4 credit, LEEDuser offers the wisdom of a team of architects, engineers, cost estimators, and LEED experts with hundreds of LEED projects between then. They analyzed the sustainable design strategies associated with each LEED credit, but also to assign actual costs to those strategies.
Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.
This information is also available in a full PDF download in The Cost of LEED v4 report.
Learn more about The Cost of LEED v4 »Frequently asked questions
Can non-potable well water that is used for irrigation contribute to potable water reduction?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
Can surface water, such as water from an irrigation ditch or a local creek, be used as nonpotable water?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
Do interior planters count in the calculation?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
We are using non-potable water for irrigation. For drought conditions, can we hook up to a potable water source for backup and still earn this credit?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
Addenda
2/2/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the first line of the second paragraph, replace the first sentence with "The baseline case uses the same reference ETo and total landscape area."
Campus Applicable
No
Internationally Applicable:
No
10/1/2012 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the definition of "graywater" with "Graywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the first paragraph, add the text "Any area that is being improved upon (for example site area that is being restored to its natural state) must be included in the landscape area."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011 – Updated: 2/14/2015
Rating System Correction
Description of change:
Replace the footnote text with the following:If the percent reduction of potable water is 100% AND the percent reduction of total water is equal to or greater than 50%, then Option 2 is earned, for a total of 4 points.
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add "or using the month with the highest irrigation demand." to the end of the first sentence.
Campus Applicable
No
Internationally Applicable:
Yes
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the fifth line of the paragraph, replace "1 year" with "18 months" so the text becomes "...a period of 18 months depending on..."
Campus Applicable
No
Internationally Applicable:
No
12/2/2009 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the second paragraph, remove the second period
Campus Applicable
No
Internationally Applicable:
No
2/2/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Below the table, replace the first sentence of the paragraph with the following:Determine, if applicable, the controller efficiency (CE), the percentage reduction in water use from any weather-based controllers or moisture sensor-based systems, not to exceed 30% for the peak month of July.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second sentence of the paragraph with "Temporary irrigation systems used for plant establishment are allowed only if removed within a period not to exceed 18 months of installation."
Campus Applicable
No
Internationally Applicable:
No
2/2/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace "CE" with "(1 - CE)"
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the first line of the first paragraph, replace the first sentence with "An office building in Austin, Texas, has 6,000 square feet of landscape area."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
Replace the second sentence of the paragraph with "Temporary irrigation systems used for plant establishment are allowed only if removed within a period not to exceed 18 months of installation."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S. box.
Campus Applicable
No
Internationally Applicable:
Yes
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second sentence with "However, if such areas are included, they must be included in all other applicable Water Efficiency credit calculations (unless otherwise noted)."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Landscape area" in alphabetical order with the accompanying text "The landscape area of the site is the total site area less the building footprint, paved surfaces, water bodies, areas being left in a natural state, and patios."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the second line, replace "year" with "18 months" so the text becomes "...during the first 18 months of building..."
Campus Applicable
No
Internationally Applicable:
No
2/1/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the second line of the last paragraph, remove the first instance of "credit" so the text becomes "...an innovative way to achieve this credit."
Campus Applicable
No
Internationally Applicable:
No
10/1/2013
LEED Interpretation
Inquiry:
In what Water Efficiency credits may desalinated seawater be applied as a non-potable water source?
Ruling:
Update October 20, 2016: See the updated “Water Use Reduction Additional Guidance” document for new guidance on applying seawater or municipal wastewater to v2009 Water Efficiency credits.
Original ruling October 1, 2013
Desalinated seawater that is not treated to potable drinking water standards may be applied as a non-potable water source in the following credits:
- WEc1 Water Efficient Landscaping
- WEc2 Innovative Wastewater Technologies
- WEc4 Cooling Tower Water Management (in LEED-EBOM)
- WEc4.2 Water Use Reduction – Cooling Towers (in LEED-Healthcare)
- WEc4 Process Water Use Reduction (in LEED-Schools for other (non-food service) equipment types such as cooling towers)
Refer to the guidance document Applicability of Seawater in Water Efficiency credits. Desalinated seawater may NOT be applied in WEp1/c3 Water Use Reduction. The focus of the water use reduction prerequisite and credit is fixture efficiency and on-site water reuse. Because sourcing water from the sea does not constitute a form of water reuse, desalinated seawater is not applicable to WEp1 regardless of whether the seawater is treated onsite or offsite. In order to take credit for using desalinated seawater as a non-potable water source in applicable Water Efficiency credits, the desalinated seawater must be:
1) Municipally supplied or explicitly approved by the municipality for on-site treatment systems,
2) Meet all applicable code and permitting requirements so as to not contaminate the system served with high salinity,
3) Treated to an appropriate level for non-potable uses, and
4) The on-site energy use to desalinate the seawater must be included in the EAp2/EAc1 calculations.
Note that seawater is water from a sea or ocean. Salty groundwater or brackish well water in coastal areas is not considered nonpotable seawater. Groundwater and water sourced from naturally occurring surface water bodies, such as streams, rivers, and lakes is also not applicable. Only seawater sourced directly from a sea or ocean may be applied
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2012
LEED Interpretation
Inquiry:
Should athletic fields be included or excluded from landscape water use calculations for WEc1?
Ruling:
All LEED projects can choose to include or exclude athletic fields at the project teams discretion from WEc1 Water Efficient Landscaping (D+C) and WEc3 Water Efficient Landscaping (EBOM). However, if such areas are included, they must be included in all other applicable credit calculations. Internationally applicable.
Campus Applicable
No
Internationally Applicable:
No
6/9/2008
LEED Interpretation
Inquiry:
This question is regarding the applicability of a process water re-use and treatment system for WE credits 1.1-3.2. Our coastal project is proposing the use of a ground-coupled open-loop heat rejection system with a side-stream desalination plant. The system draws non-potable brackish water from the ground, rejects heat from cogeneration and HVAC systems into the water and returns the rejected process water to the ground. The water is not potable source water (e.g. sourced from potable watersheds such as lakes and rivers) and stringent environmental regulations are in place with regard to pumping rates / volume, and quality of the return water. Approximately 10% of the rejected process water flow is diverted for re-use in the building. The diverted water is treated using a reverse osmosis desalination system. The treated water will be used onsite for irrigation and conveyance. Benefits of this system include a reduced impact on the already taxed local potable water supply, reliability of water source, and environmental benefit due to on site treatment and re-use. We believe we should be able to take credit for the municipal water savings resulting from this system, provided that energy use from the system is included in energy calculations. Please provide guidance for credit applicability.
Ruling:
The applicant is inquiring as to acceptability of a process water re-use and treatment system for WE credits. In previous CIRs, recycled on-site water (such as water from a cooling tower) has been accepted for credit compliance. However, in this case, the portion of brackish water not returning to the ground from the ground-coupled open loop rejection system, which would be diverted for re-use on site, can not be used as is. Before this water could be put to any use, it would require going through Reverse Osmosis (RO) treatment which is an energy intensive process. The applicant is correct in suggesting that using this water would reduce/eliminate the need to use municipal potable water for landscape irrigation. In order to take credit for using non-potable water the energy use to desalinate the water must also be included in the EAc1 calculations. In addition, it should be noted that the intent of this credit is to encourage water efficient or xeriscape landscaping practices, which require little to no irrigation and/or use no potable water for irrigation. Hence, the project team should be ready to document the overall approach towards meeting the intent of the credit. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
4/8/2009
LEED Interpretation
Inquiry:
The mechanical systems for this project are geothermal in design. Non-domestic use well water is supplied via a closed loop to an isolated heat pump heat exchanger to provide climate control of the building. The uncontaminated well water is then returned to the ground via a separate well, at a location different from where it was extracted. We would like to use a portion of this discharge well water for site irrigation. Our question is; will this water be considered a non-potable source to help achieve WE Credit 1.2? Our opinion is that this returned well water should be considered non-potable since its use in the irrigation system is secondary to the use of the geothermal system. Also, in using this water in the irrigation system, it is being applied to the landscape and provides a positive impact on the ground water table in the fact that it will replace soil moisture that would have been evaporated from the soil surface and therefore diminishing the moisture levels deeper within the soil profile. A certain portion of this water will also migrate through the soil profile back into the water table.
Ruling:
The applicant is requesting approval to use water extracted from the outlet of an open-loop ground source heat pump for irrigation. The proposed approach does not satisfy the intent of the credit. The irrigation water would be provided indirectly from natural subsurface water to provide a condensing/heating source for the ground source heat pump. The LEED-NC v2.2 Reference Guide states that the credit intent is to "limit or eliminate the use of potable water, or other natural surface or subsurface water resources available on or near the project site, for landscape irrigation." This issue has also been addressed by CIRs dated 1/13/2003, 10/23/2001, and 6/9/2008. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:
The intent of this credit is to alter planting details to eliminate the use of potable water for landscape irrigation as much as possible. Project teams tend to interpret "landscape" as any vegetated space on the project site. However, some projects also include growing space for food in an urban agriculture or community garden setting. This is not "landscape" in the usual sense, and the normal water use reduction measures aren\'t appropriate when the land is being used productively. In LEED for Homes, an existing LEED Interpretation clarifies that growing space should be exempted entirely from the calculations for the Homes version of this credit (do not include in the numerator or denominator). See LI 2736. I request that this LI be extended to all LEED rating systems, since growing space is potentially a component of many project types.
Ruling:
Project teams may elect to exclude food gardens from landscape calculations on the rationale that normal water use reduction measures are not appropriate when the land is being used to produce food for human consumption. If a project team chooses to exclude a food garden from the landscape area, it should be excluded uniformly across the baseline and design calculations.
Campus Applicable
No
Internationally Applicable:
No
7/1/2012
LEED Interpretation
Inquiry:
Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?
Ruling:
Update October 20, 2016: See the updated “Water Use Reduction Additional Guidance” document for new guidance on applying seawater or municipal wastewater to v2009 Water Efficiency credits.
Update October 1, 2013
Note that LEED Interpretation 10117 has been updated to clarify that seawater must be treated to appropriate levels for non-potable uses in order to apply to WEc2 Innovative Wastewater Technologies; seawater that is treated to potable drinking water standards would not apply. Any on-site energy use to desalinate the seawater must be included in the EAp2/c1 calculations. Refer to the guidance document. Applicability of Seawater in Water Efficiency credits also updated.
Original ruling July 1, 2012
No, municipally supplied sources of non-potable water, including seawater, are not applicable to the WE fixture water use reduction credits, including WEp1 (D+C, EBOM) and WEc1 (CI) Water Use Reduction, or considered graywater. As stated in LI 1551 (12/12/2006) This credit focuses on fixture efficiency and on-site water reuse. In addition, the Water Use Reduction Additional Guidance document (updated 8/16/2010, http://www.usgbc.org/ShowFile.aspx?DocumentID=6493), confirms that the focus of the pre-requisite is water efficiency of the installed fixtures, regardless of the water source, and only on-site water reuse is available as an alternative compliance path.
However, municipally treated wastewater (including treated seawater) applies to SSc1 - Path 9 Innovative Wastewater Technologies (CI), WEc2, Innovative Wastewater Technologies (BD+C), and can be used if the two conditions of LEED Interpretation 10117 are met: 1) the seawater is municipally supplied or explicitly approved by the municipality and 2) meets all applicable codes and permitting requirements, so as not to contaminate the municipal wastewater system with high salinity. For EBOM projects, where no wastewater credit is available, the project may apply for innovation credit for use of this strategy."
----------
10/1/13 notes: revise ruling and update resource: http://www.usgbc.org/resources/seawater-guidance
No, municipally supplied sources of non-potable water, including seawater, are not applicable to the WE fixture water use reduction credits, including WEp1 (D+C, EBOM) and WEc1 (CI) Water Use Reduction, or considered graywater. As stated in LI 1551 (12/12/2006) This credit focuses on fixture efficiency and on-site water reuse. In addition, the Water Use Reduction Additional Guidance document (updated 8/16/2010, http://www.usgbc.org/ShowFile.aspx?DocumentID=6493), confirms that the focus of the prerequisite is water efficiency of the installed fixtures, regardless of the water source, and only on-site water reuse is available as an alternative compliance path.
However, municipally treated wastewater (including treated seawater) applies to SSc1 - Path 9 Innovative Wastewater Technologies (CI), WEc2, Innovative Wastewater Technologies (BD+C), and can be used if the two conditions of LEED Interpretation 10117 are met: 1) the seawater is municipally supplied or explicitly approved by the municipality and 2) meets all applicable codes and permitting requirements, so as not to contaminate the municipal wastewater system with high salinity. For EBOM projects, where no wastewater credit is available, the project may apply for innovation credit for use of this strategy.
**Update October 1, 2013: Note that LEED Interpretation 10117 has been updated to clarify that seawater must be treated to appropriate levels for non-potable uses in order to apply to WEc2 Innovative Wastewater Technologies; seawater that is treated to potable drinking water standards would not apply. Any on-site energy use to desalinate the seawater must be included in the EAp2/c1 calculations. Refer to the guidance document. Applicability of Seawater in Water Efficiency credits also updated
Campus Applicable
No
Internationally Applicable:
No
7/1/2012
LEED Interpretation
Inquiry:
Can an alternative compliance path for WEc1.2 Water Efficient Landscaping, No Potable Water Use or No Irrigation be created by demonstrating that an equal or greater amount of rainwater, required for irrigation, is reused on site, while irrigating a portion of the landscape with potable water?
Ruling:
This strategy, while positive, does not adequately address the intent of the credit to limit or eliminate the use of potable water resources for landscape irrigation. As long as there is a 50% reduction in potable water, one point will be earned regardless of the irrigation source and one additional point is earned when no potable water is used for irrigation and there is a 50% reduction in Total Water Applied (TWA). While the project is correct in suggesting that the avoided energy and lower operating costs justifies the design approach, this is not a deciding factor in this credit. Internationally applicable.
Campus Applicable
No
Internationally Applicable:
No
9/19/2006
LEED Interpretation
Inquiry:
I am the LEED administrator for a Water Treatment Plant project (currently registered on LEED On-line, v2.2) We are not pursing LEED certification for the entire treatment facility. We are only pursuing LEED Certification for the primary building on the site (Administration/Operations Center). We have established a reasonable and consistent boundary for the subject building (including Sustainable Site considerations). As a water treatment facility, the project involves accessing water rights from the adjacent river for processing, treatment, and distribution of water to the public. In order to meet the criteria for WE Credit 1.1, 1.2 - Water Efficient Landscaping - we are considering: 1. Plant species factor 2. Use of captured rainwater - when available from the proposed on site stormwater retention basin and 3. Use of raw water - directly from the river For item 3 above, I have noted previous CIR\'s on this subject which deny the use of river water for this credit. I have also noted in the Reference Guide that the intent is to limit or eliminate the use of natural surface or subsurface resources for irrigation purposes. Yet, in the Reference Guide, page 115, under Requirements, "Use of water treated and conveyed by a public agency specifically for non-potable uses" is noted as a consideration. Most water (potable or non-potable) conveyed by a public agency is ultimately sourced from surface or subsurface resources. Therefore, it seems that an office building project, for example, could use non-potable water conveyed by our agency and that project would be eligible to gain the LEED credit. Whereas if our agency uses the same water for itself, the credit would not be granted. This raw, un-treated water, which would normally be processed through the treatment plant, will be diverted from the processing and treatment stream (saving energy and use of chemicals) and will be used directly for irrigation for the landscaping within the proposed LEED boundary surrounding the subject building on the water treatment plant site. We would like to confirm that USGBC concurs with our interpretation that this proposed source for irrigation water from the river (non-potable, raw water) will meet the intent of WE c1.1, 1.2. We believe that in essence, this raw water is equivalent to (is actually environmentally better than) "Use of water TREATED and conveyed by a public agency specifically for non-potable uses" as indicated on page 115 of v2.2 Reference Guide).
Ruling:
Plant species factor and onsite captured rainwater are qualifying strategies to achieve this credit. Based on v2.1 WEc1.2 CIR rulings dated 1/20/04 and 11/5/2005, the use of surface water or water drawn from receiving waters is not an acceptable way to meet the credit intent. LEED-NC v2.2 WEc1 allows the, "Use of water treated and conveyed by a public agency specifically for non-potable uses," however, these sources are not typically "sourced from surface or subsurface resources." Common sources include effluent from treatment plants and recycled graywater harvested from within the region. If this water treatment plant supplies water to offsite customers specifically for non-potable uses AND the raw water proposed for irrigation would otherwise be processed for this non-potable system, then the intent of the credit has been met. While the avoided energy and chemical inputs for this raw water are laudable, this is not a deciding factor. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
6/19/2008
LEED Interpretation
Inquiry:
The project is a renovation of a part of a student residence hall, which is part of a large university campus facilities program. Thus, drip irrigation is not proposed due to its higher maintenance requirements. The Reference Guide provides only two methods of irrigation in order to calculate efficiency: spray and drip. Spray irrigation is rated at 62.5% efficient while drip irrigation is rated at 90.0%. We feel there are more than just two options to calculate irrigation efficiency (IE) as it pertains to this credit. Not all at-grade irrigation equipment should be generalized as "spray" irrigation. There are fixed-arc spray heads, which have efficiencies as suggested by USGBC, and there are rotary heads that are more efficient. Rotary heads can provide a greater radius of coverage and dispense water at a lower precipitation rate. For the larger turf areas at this site, rotary heads provide higher uniformity. We can prove with credit submittal documentation that the IE of rotating sprinkler heads at a minimum is 75.0%. Rotary heads will not cover all turf areas; the remainder will have to be covered by fixed-arc spray heads. We are partitioning water consumption calculations in the design case by irrigation method and assigning the appropriate IE to each. Shrub areas are proposed with fixed-arc spray heads. The fixed-arc spray heads proposed have a pressure-regulating feature that reduces pressure at the nozzle to an optimum level. Fixed-arc spray head nozzles are designed to dispense a certain amount of water over a given area. A properly pressurized spray head and nozzle issues water droplets that are sized so as to not be affected by wind and sun and throw the proper distances. When pressure is too high, water droplets become finer (mist) and the spray patterns become distorted from slight breezes. This effect decreases efficiency, requiring longer irrigation times and more water to be dispensed in order to obtain the proper net result. Not all heads have the pressure-regulating feature. Heads that do contain this feature regulate pressure to their optimum of 30 psi. 60-psi pressure at the spray heads is available. Per the manufacturer\'s data (to be submitted), water consumption with pressure regulation is 71.0% of standard fixed-arc designs. Rotary heads do not have this feature and require the full 60-psi available. Irrigation controls are intended to automatically adjust watering times based on local climate conditions. Conventional controllers are set to turn irrigation on at the same time everyday for the same duration. The campus utilizes a central control system with weather station to manage irrigation duration. Evapotranspiration (ET)-based controllers receive central control signals and adjust irrigation times based on daily weather. Rain sensors enhance water savings further by suspending the daily irrigation cycle depending on how intense rainstorms are. The irrigation engineer calculates that an ET-based controller dispenses only 61.1% of the water used by a system with typical controls in the month of July at our location (to be submitted). In the spirit of controller efficiencies as suggested in the Reference Manual, we request that the USGBC allow us to expand the credit calculation analysis to include the efficiencies and reductions expected by specifying rotating heads, pressure-regulating heads, and ET-based controlling. Our project will have at least a 53.6% reduction in potable water consumption during the month of July compared to typical irrigation system with the same landscaping scheme.
Ruling:
The project is requesting clarification on whether or not efficiencies other than those associated with spray and drip irrigation heads (0.625 and 0.9 respectively) can be used in the calculations to determine total water applied. The use of alternate efficiencies for different types of irrigation heads is acceptable. However, similar to the percent reduction in water use attributed to ET-based controllers, the reported efficiencies of alternate irrigation head types must be supported by manufacturer documentation or detailed calculations by the landscape designer or irrigation engineer. The supporting calculations for the design irrigation head efficiency cannot simply be based on a comparison to the usage rate seen in a less efficient standard or baseline irrigation head as suggested by the CIR. The reported efficiency of any irrigation head type must be a measure of the amount of water that actually reaches and is used by the plant materials and must address both evaporation and drift losses. ET-based controllers are already accounted for in Equation 3 as detailed on page 121 of the LEED-NC v2.2 Reference Guide. Further, the percent reduction in water use attributed to any weather-based controller or moisture sensor-based systems must be supported by manufacturer documentation and detailed calculations by the landscape designer or irrigation engineer. Partitioning the project into areas by irrigation type is acceptable. However this does not exempt the project from demonstrating compliance with the water use calculation methods detailed in the Reference Guide. For example, the areas that are partitioned by irrigation type must obviously also take into account sub-areas with specific plant types, microclimates and densities. These sub-areas will have distinct evapotranspiration rates which should be calculated using the appropriate landscape coefficient (KL) for that area. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:
Are calculations based on annual irrigation water use acceptable to earn the credit if it is demonstrated that annual water savings of 50% or greater, due to the use of a weather tracking controller and periods of no irrigation, can be achieved?
Ruling:
Although the strategies used to decrease annual water savings are commendable, the proposed approach is not acceptable. In this credit, all calculations are based on July as a proxy for the peak water demand month. Applicable internationally.
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2016
LEED Interpretation
Inquiry:
Can the EPA Watersense Water Budget Tool be used on 2009 projects? Can EBOM projects use the Option 2 theoretical calculation for Option 1? If so, what are the parameters?
Ruling:
Yes, the EPA Watersense Water Budget Tool can be used for v2009 BD+C and O+M projects. The thresholds in v2009 must still be documented; there is no v4 substitute. The v2009 controller efficiency criteria still holds (e.g. controller efficiency savings are limited to 30%).
EBOM Option 1: projects can use the theoretical calculation from Option 2 to establish the baseline for Option 1. The theoretical baseline case should be calculated using the month of July or the month with the highest irrigation demand and must be compared to metered water use data from that same month. Average values must be used for plant species, density and microclimate factor.
EBOM Option 2: percentage savings can be documented using the Water Budget Tool in place of the theoretical calculations.
EBOM Option 3: the Water Budget Tool can be considered an independent irrigation performance tool. Compare the project's metered water use against the baseline, not the landscape water allowance (LWA).
Campus Applicable
Yes
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:
The intent of this credit is to alter planting details to eliminate the use of potable water for landscape irrigation as much as possible. Project teams tend to interpret "landscape" as any vegetated space on the project site. However, some projects also include growing space for food in an urban agriculture or community garden setting. This is not "landscape" in the usual sense, and the normal water use reduction measures aren\'t appropriate when the land is being used productively. In LEED for Homes, an existing LEED Interpretation clarifies that growing space should be exempted entirely from the calculations for the Homes version of this credit (do not include in the numerator or denominator). See LI 2736. I request that this LI be extended to all LEED rating systems, since growing space is potentially a component of many project types.
Ruling:
Project teams may elect to exclude food gardens from landscape calculations on the rationale that normal water use reduction measures are not appropriate when the land is being used to produce food for human consumption. If a project team chooses to exclude a food garden from the landscape area, it should be excluded uniformly across the baseline and design calculations.
Campus Applicable
No
Internationally Applicable:
No
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Requirements
OPTION 1: Reduce by 50% (2 points)
Reduce potable water consumption for irrigation by 50% from a calculated midsummer baseline case or using the month with the highest irrigation demand. Reductions must be attributed to any combination of the following items:- Plant species, density and microclimate factor
- Irrigation efficiency
- Use of captured rainwater
- Use of recycled wastewater
- Use of water treated and conveyed by a public agency specifically for nonpotable uses
OR
Option 2: No potable water use or irrigation1 (4 points)
Meet the requirements for Option 1.AND
PATH 1
Use only captured rainwater, recycled wastewater, recycled graywater or water treated and conveyed by a public agency specifically for nonpotable uses for irrigation.OR
PATH 2
Install landscaping that does not require permanent irrigation systems. Temporary irrigation systems used for plant establishment are allowed only if removed within a period not to exceed 18 months of installation.SITES-LEED Equivalency
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.XX%
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Can non-potable well water that is used for irrigation contribute to potable water reduction?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
Can surface water, such as water from an irrigation ditch or a local creek, be used as nonpotable water?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
Do interior planters count in the calculation?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
We are using non-potable water for irrigation. For drought conditions, can we hook up to a potable water source for backup and still earn this credit?The answer to this question is available to LEEDuser premium members. Start a free trial » (If you're already a premium member, log in here.) |
2/2/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the paragraph beginning with "Using groundwater...", replace the last sentence with the following:Additionally the credit can be met when landscape irrigation is provided by raw water (excluding naturally occurring surface bodies of water, streams, or rivers, and ground water) that would otherwise be treated specifically for nonpotable uses. Only ponds designed solely for the purposes of stormwater retention or detention can be used for this credit.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the first line of the second paragraph, replace the first sentence with "The baseline case uses the same reference ETo and total landscape area."
Campus Applicable
No
Internationally Applicable:
No
10/1/2012 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the definition of "graywater" with "Graywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the first paragraph, add the text "Any area that is being improved upon (for example site area that is being restored to its natural state) must be included in the landscape area."
Campus Applicable
No
Internationally Applicable:
No
5/9/2011 – Updated: 2/14/2015
Rating System Correction
Description of change:
Replace the footnote text with the following:If the percent reduction of potable water is 100% AND the percent reduction of total water is equal to or greater than 50%, then Option 2 is earned, for a total of 4 points.
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add "or using the month with the highest irrigation demand." to the end of the first sentence.
Campus Applicable
No
Internationally Applicable:
Yes
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the fifth line of the paragraph, replace "1 year" with "18 months" so the text becomes "...a period of 18 months depending on..."
Campus Applicable
No
Internationally Applicable:
No
12/2/2009 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
At the end of the second paragraph, remove the second period
Campus Applicable
No
Internationally Applicable:
No
2/2/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Below the table, replace the first sentence of the paragraph with the following:Determine, if applicable, the controller efficiency (CE), the percentage reduction in water use from any weather-based controllers or moisture sensor-based systems, not to exceed 30% for the peak month of July.
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second sentence of the paragraph with "Temporary irrigation systems used for plant establishment are allowed only if removed within a period not to exceed 18 months of installation."
Campus Applicable
No
Internationally Applicable:
No
2/2/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace "CE" with "(1 - CE)"
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the first line of the first paragraph, replace the first sentence with "An office building in Austin, Texas, has 6,000 square feet of landscape area."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Rating System Correction
Description of change:
Replace the second sentence of the paragraph with "Temporary irrigation systems used for plant establishment are allowed only if removed within a period not to exceed 18 months of installation."
Campus Applicable
No
Internationally Applicable:
No
7/6/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Delete the Alternative Compliance Path for Projects Outside the U.S. box.
Campus Applicable
No
Internationally Applicable:
Yes
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Replace the second sentence with "However, if such areas are included, they must be included in all other applicable Water Efficiency credit calculations (unless otherwise noted)."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Insert the term "Landscape area" in alphabetical order with the accompanying text "The landscape area of the site is the total site area less the building footprint, paved surfaces, water bodies, areas being left in a natural state, and patios."
Campus Applicable
No
Internationally Applicable:
No
7/19/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the second line, replace "year" with "18 months" so the text becomes "...during the first 18 months of building..."
Campus Applicable
No
Internationally Applicable:
No
2/1/2010 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
In the second line of the last paragraph, remove the first instance of "credit" so the text becomes "...an innovative way to achieve this credit."
Campus Applicable
No
Internationally Applicable:
No
10/1/2013
LEED Interpretation
Inquiry:
In what Water Efficiency credits may desalinated seawater be applied as a non-potable water source?
Ruling:
Update October 20, 2016: See the updated “Water Use Reduction Additional Guidance” document for new guidance on applying seawater or municipal wastewater to v2009 Water Efficiency credits.
Original ruling October 1, 2013
Desalinated seawater that is not treated to potable drinking water standards may be applied as a non-potable water source in the following credits:
- WEc1 Water Efficient Landscaping
- WEc2 Innovative Wastewater Technologies
- WEc4 Cooling Tower Water Management (in LEED-EBOM)
- WEc4.2 Water Use Reduction – Cooling Towers (in LEED-Healthcare)
- WEc4 Process Water Use Reduction (in LEED-Schools for other (non-food service) equipment types such as cooling towers)
Refer to the guidance document Applicability of Seawater in Water Efficiency credits. Desalinated seawater may NOT be applied in WEp1/c3 Water Use Reduction. The focus of the water use reduction prerequisite and credit is fixture efficiency and on-site water reuse. Because sourcing water from the sea does not constitute a form of water reuse, desalinated seawater is not applicable to WEp1 regardless of whether the seawater is treated onsite or offsite. In order to take credit for using desalinated seawater as a non-potable water source in applicable Water Efficiency credits, the desalinated seawater must be:
1) Municipally supplied or explicitly approved by the municipality for on-site treatment systems,
2) Meet all applicable code and permitting requirements so as to not contaminate the system served with high salinity,
3) Treated to an appropriate level for non-potable uses, and
4) The on-site energy use to desalinate the seawater must be included in the EAp2/EAc1 calculations.
Note that seawater is water from a sea or ocean. Salty groundwater or brackish well water in coastal areas is not considered nonpotable seawater. Groundwater and water sourced from naturally occurring surface water bodies, such as streams, rivers, and lakes is also not applicable. Only seawater sourced directly from a sea or ocean may be applied
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2012
LEED Interpretation
Inquiry:
Should athletic fields be included or excluded from landscape water use calculations for WEc1?
Ruling:
All LEED projects can choose to include or exclude athletic fields at the project teams discretion from WEc1 Water Efficient Landscaping (D+C) and WEc3 Water Efficient Landscaping (EBOM). However, if such areas are included, they must be included in all other applicable credit calculations. Internationally applicable.
Campus Applicable
No
Internationally Applicable:
No
6/9/2008
LEED Interpretation
Inquiry:
This question is regarding the applicability of a process water re-use and treatment system for WE credits 1.1-3.2. Our coastal project is proposing the use of a ground-coupled open-loop heat rejection system with a side-stream desalination plant. The system draws non-potable brackish water from the ground, rejects heat from cogeneration and HVAC systems into the water and returns the rejected process water to the ground. The water is not potable source water (e.g. sourced from potable watersheds such as lakes and rivers) and stringent environmental regulations are in place with regard to pumping rates / volume, and quality of the return water. Approximately 10% of the rejected process water flow is diverted for re-use in the building. The diverted water is treated using a reverse osmosis desalination system. The treated water will be used onsite for irrigation and conveyance. Benefits of this system include a reduced impact on the already taxed local potable water supply, reliability of water source, and environmental benefit due to on site treatment and re-use. We believe we should be able to take credit for the municipal water savings resulting from this system, provided that energy use from the system is included in energy calculations. Please provide guidance for credit applicability.
Ruling:
The applicant is inquiring as to acceptability of a process water re-use and treatment system for WE credits. In previous CIRs, recycled on-site water (such as water from a cooling tower) has been accepted for credit compliance. However, in this case, the portion of brackish water not returning to the ground from the ground-coupled open loop rejection system, which would be diverted for re-use on site, can not be used as is. Before this water could be put to any use, it would require going through Reverse Osmosis (RO) treatment which is an energy intensive process. The applicant is correct in suggesting that using this water would reduce/eliminate the need to use municipal potable water for landscape irrigation. In order to take credit for using non-potable water the energy use to desalinate the water must also be included in the EAc1 calculations. In addition, it should be noted that the intent of this credit is to encourage water efficient or xeriscape landscaping practices, which require little to no irrigation and/or use no potable water for irrigation. Hence, the project team should be ready to document the overall approach towards meeting the intent of the credit. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
4/8/2009
LEED Interpretation
Inquiry:
The mechanical systems for this project are geothermal in design. Non-domestic use well water is supplied via a closed loop to an isolated heat pump heat exchanger to provide climate control of the building. The uncontaminated well water is then returned to the ground via a separate well, at a location different from where it was extracted. We would like to use a portion of this discharge well water for site irrigation. Our question is; will this water be considered a non-potable source to help achieve WE Credit 1.2? Our opinion is that this returned well water should be considered non-potable since its use in the irrigation system is secondary to the use of the geothermal system. Also, in using this water in the irrigation system, it is being applied to the landscape and provides a positive impact on the ground water table in the fact that it will replace soil moisture that would have been evaporated from the soil surface and therefore diminishing the moisture levels deeper within the soil profile. A certain portion of this water will also migrate through the soil profile back into the water table.
Ruling:
The applicant is requesting approval to use water extracted from the outlet of an open-loop ground source heat pump for irrigation. The proposed approach does not satisfy the intent of the credit. The irrigation water would be provided indirectly from natural subsurface water to provide a condensing/heating source for the ground source heat pump. The LEED-NC v2.2 Reference Guide states that the credit intent is to "limit or eliminate the use of potable water, or other natural surface or subsurface water resources available on or near the project site, for landscape irrigation." This issue has also been addressed by CIRs dated 1/13/2003, 10/23/2001, and 6/9/2008. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:
The intent of this credit is to alter planting details to eliminate the use of potable water for landscape irrigation as much as possible. Project teams tend to interpret "landscape" as any vegetated space on the project site. However, some projects also include growing space for food in an urban agriculture or community garden setting. This is not "landscape" in the usual sense, and the normal water use reduction measures aren\'t appropriate when the land is being used productively. In LEED for Homes, an existing LEED Interpretation clarifies that growing space should be exempted entirely from the calculations for the Homes version of this credit (do not include in the numerator or denominator). See LI 2736. I request that this LI be extended to all LEED rating systems, since growing space is potentially a component of many project types.
Ruling:
Project teams may elect to exclude food gardens from landscape calculations on the rationale that normal water use reduction measures are not appropriate when the land is being used to produce food for human consumption. If a project team chooses to exclude a food garden from the landscape area, it should be excluded uniformly across the baseline and design calculations.
Campus Applicable
No
Internationally Applicable:
No
7/1/2012
LEED Interpretation
Inquiry:
Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?
Ruling:
Update October 20, 2016: See the updated “Water Use Reduction Additional Guidance” document for new guidance on applying seawater or municipal wastewater to v2009 Water Efficiency credits.
Update October 1, 2013
Note that LEED Interpretation 10117 has been updated to clarify that seawater must be treated to appropriate levels for non-potable uses in order to apply to WEc2 Innovative Wastewater Technologies; seawater that is treated to potable drinking water standards would not apply. Any on-site energy use to desalinate the seawater must be included in the EAp2/c1 calculations. Refer to the guidance document. Applicability of Seawater in Water Efficiency credits also updated.
Original ruling July 1, 2012
No, municipally supplied sources of non-potable water, including seawater, are not applicable to the WE fixture water use reduction credits, including WEp1 (D+C, EBOM) and WEc1 (CI) Water Use Reduction, or considered graywater. As stated in LI 1551 (12/12/2006) This credit focuses on fixture efficiency and on-site water reuse. In addition, the Water Use Reduction Additional Guidance document (updated 8/16/2010, http://www.usgbc.org/ShowFile.aspx?DocumentID=6493), confirms that the focus of the pre-requisite is water efficiency of the installed fixtures, regardless of the water source, and only on-site water reuse is available as an alternative compliance path.
However, municipally treated wastewater (including treated seawater) applies to SSc1 - Path 9 Innovative Wastewater Technologies (CI), WEc2, Innovative Wastewater Technologies (BD+C), and can be used if the two conditions of LEED Interpretation 10117 are met: 1) the seawater is municipally supplied or explicitly approved by the municipality and 2) meets all applicable codes and permitting requirements, so as not to contaminate the municipal wastewater system with high salinity. For EBOM projects, where no wastewater credit is available, the project may apply for innovation credit for use of this strategy."
----------
10/1/13 notes: revise ruling and update resource: http://www.usgbc.org/resources/seawater-guidance
No, municipally supplied sources of non-potable water, including seawater, are not applicable to the WE fixture water use reduction credits, including WEp1 (D+C, EBOM) and WEc1 (CI) Water Use Reduction, or considered graywater. As stated in LI 1551 (12/12/2006) This credit focuses on fixture efficiency and on-site water reuse. In addition, the Water Use Reduction Additional Guidance document (updated 8/16/2010, http://www.usgbc.org/ShowFile.aspx?DocumentID=6493), confirms that the focus of the prerequisite is water efficiency of the installed fixtures, regardless of the water source, and only on-site water reuse is available as an alternative compliance path.
However, municipally treated wastewater (including treated seawater) applies to SSc1 - Path 9 Innovative Wastewater Technologies (CI), WEc2, Innovative Wastewater Technologies (BD+C), and can be used if the two conditions of LEED Interpretation 10117 are met: 1) the seawater is municipally supplied or explicitly approved by the municipality and 2) meets all applicable codes and permitting requirements, so as not to contaminate the municipal wastewater system with high salinity. For EBOM projects, where no wastewater credit is available, the project may apply for innovation credit for use of this strategy.
**Update October 1, 2013: Note that LEED Interpretation 10117 has been updated to clarify that seawater must be treated to appropriate levels for non-potable uses in order to apply to WEc2 Innovative Wastewater Technologies; seawater that is treated to potable drinking water standards would not apply. Any on-site energy use to desalinate the seawater must be included in the EAp2/c1 calculations. Refer to the guidance document. Applicability of Seawater in Water Efficiency credits also updated
Campus Applicable
No
Internationally Applicable:
No
7/1/2012
LEED Interpretation
Inquiry:
Can an alternative compliance path for WEc1.2 Water Efficient Landscaping, No Potable Water Use or No Irrigation be created by demonstrating that an equal or greater amount of rainwater, required for irrigation, is reused on site, while irrigating a portion of the landscape with potable water?
Ruling:
This strategy, while positive, does not adequately address the intent of the credit to limit or eliminate the use of potable water resources for landscape irrigation. As long as there is a 50% reduction in potable water, one point will be earned regardless of the irrigation source and one additional point is earned when no potable water is used for irrigation and there is a 50% reduction in Total Water Applied (TWA). While the project is correct in suggesting that the avoided energy and lower operating costs justifies the design approach, this is not a deciding factor in this credit. Internationally applicable.
Campus Applicable
No
Internationally Applicable:
No
9/19/2006
LEED Interpretation
Inquiry:
I am the LEED administrator for a Water Treatment Plant project (currently registered on LEED On-line, v2.2) We are not pursing LEED certification for the entire treatment facility. We are only pursuing LEED Certification for the primary building on the site (Administration/Operations Center). We have established a reasonable and consistent boundary for the subject building (including Sustainable Site considerations). As a water treatment facility, the project involves accessing water rights from the adjacent river for processing, treatment, and distribution of water to the public. In order to meet the criteria for WE Credit 1.1, 1.2 - Water Efficient Landscaping - we are considering: 1. Plant species factor 2. Use of captured rainwater - when available from the proposed on site stormwater retention basin and 3. Use of raw water - directly from the river For item 3 above, I have noted previous CIR\'s on this subject which deny the use of river water for this credit. I have also noted in the Reference Guide that the intent is to limit or eliminate the use of natural surface or subsurface resources for irrigation purposes. Yet, in the Reference Guide, page 115, under Requirements, "Use of water treated and conveyed by a public agency specifically for non-potable uses" is noted as a consideration. Most water (potable or non-potable) conveyed by a public agency is ultimately sourced from surface or subsurface resources. Therefore, it seems that an office building project, for example, could use non-potable water conveyed by our agency and that project would be eligible to gain the LEED credit. Whereas if our agency uses the same water for itself, the credit would not be granted. This raw, un-treated water, which would normally be processed through the treatment plant, will be diverted from the processing and treatment stream (saving energy and use of chemicals) and will be used directly for irrigation for the landscaping within the proposed LEED boundary surrounding the subject building on the water treatment plant site. We would like to confirm that USGBC concurs with our interpretation that this proposed source for irrigation water from the river (non-potable, raw water) will meet the intent of WE c1.1, 1.2. We believe that in essence, this raw water is equivalent to (is actually environmentally better than) "Use of water TREATED and conveyed by a public agency specifically for non-potable uses" as indicated on page 115 of v2.2 Reference Guide).
Ruling:
Plant species factor and onsite captured rainwater are qualifying strategies to achieve this credit. Based on v2.1 WEc1.2 CIR rulings dated 1/20/04 and 11/5/2005, the use of surface water or water drawn from receiving waters is not an acceptable way to meet the credit intent. LEED-NC v2.2 WEc1 allows the, "Use of water treated and conveyed by a public agency specifically for non-potable uses," however, these sources are not typically "sourced from surface or subsurface resources." Common sources include effluent from treatment plants and recycled graywater harvested from within the region. If this water treatment plant supplies water to offsite customers specifically for non-potable uses AND the raw water proposed for irrigation would otherwise be processed for this non-potable system, then the intent of the credit has been met. While the avoided energy and chemical inputs for this raw water are laudable, this is not a deciding factor. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
6/19/2008
LEED Interpretation
Inquiry:
The project is a renovation of a part of a student residence hall, which is part of a large university campus facilities program. Thus, drip irrigation is not proposed due to its higher maintenance requirements. The Reference Guide provides only two methods of irrigation in order to calculate efficiency: spray and drip. Spray irrigation is rated at 62.5% efficient while drip irrigation is rated at 90.0%. We feel there are more than just two options to calculate irrigation efficiency (IE) as it pertains to this credit. Not all at-grade irrigation equipment should be generalized as "spray" irrigation. There are fixed-arc spray heads, which have efficiencies as suggested by USGBC, and there are rotary heads that are more efficient. Rotary heads can provide a greater radius of coverage and dispense water at a lower precipitation rate. For the larger turf areas at this site, rotary heads provide higher uniformity. We can prove with credit submittal documentation that the IE of rotating sprinkler heads at a minimum is 75.0%. Rotary heads will not cover all turf areas; the remainder will have to be covered by fixed-arc spray heads. We are partitioning water consumption calculations in the design case by irrigation method and assigning the appropriate IE to each. Shrub areas are proposed with fixed-arc spray heads. The fixed-arc spray heads proposed have a pressure-regulating feature that reduces pressure at the nozzle to an optimum level. Fixed-arc spray head nozzles are designed to dispense a certain amount of water over a given area. A properly pressurized spray head and nozzle issues water droplets that are sized so as to not be affected by wind and sun and throw the proper distances. When pressure is too high, water droplets become finer (mist) and the spray patterns become distorted from slight breezes. This effect decreases efficiency, requiring longer irrigation times and more water to be dispensed in order to obtain the proper net result. Not all heads have the pressure-regulating feature. Heads that do contain this feature regulate pressure to their optimum of 30 psi. 60-psi pressure at the spray heads is available. Per the manufacturer\'s data (to be submitted), water consumption with pressure regulation is 71.0% of standard fixed-arc designs. Rotary heads do not have this feature and require the full 60-psi available. Irrigation controls are intended to automatically adjust watering times based on local climate conditions. Conventional controllers are set to turn irrigation on at the same time everyday for the same duration. The campus utilizes a central control system with weather station to manage irrigation duration. Evapotranspiration (ET)-based controllers receive central control signals and adjust irrigation times based on daily weather. Rain sensors enhance water savings further by suspending the daily irrigation cycle depending on how intense rainstorms are. The irrigation engineer calculates that an ET-based controller dispenses only 61.1% of the water used by a system with typical controls in the month of July at our location (to be submitted). In the spirit of controller efficiencies as suggested in the Reference Manual, we request that the USGBC allow us to expand the credit calculation analysis to include the efficiencies and reductions expected by specifying rotating heads, pressure-regulating heads, and ET-based controlling. Our project will have at least a 53.6% reduction in potable water consumption during the month of July compared to typical irrigation system with the same landscaping scheme.
Ruling:
The project is requesting clarification on whether or not efficiencies other than those associated with spray and drip irrigation heads (0.625 and 0.9 respectively) can be used in the calculations to determine total water applied. The use of alternate efficiencies for different types of irrigation heads is acceptable. However, similar to the percent reduction in water use attributed to ET-based controllers, the reported efficiencies of alternate irrigation head types must be supported by manufacturer documentation or detailed calculations by the landscape designer or irrigation engineer. The supporting calculations for the design irrigation head efficiency cannot simply be based on a comparison to the usage rate seen in a less efficient standard or baseline irrigation head as suggested by the CIR. The reported efficiency of any irrigation head type must be a measure of the amount of water that actually reaches and is used by the plant materials and must address both evaporation and drift losses. ET-based controllers are already accounted for in Equation 3 as detailed on page 121 of the LEED-NC v2.2 Reference Guide. Further, the percent reduction in water use attributed to any weather-based controller or moisture sensor-based systems must be supported by manufacturer documentation and detailed calculations by the landscape designer or irrigation engineer. Partitioning the project into areas by irrigation type is acceptable. However this does not exempt the project from demonstrating compliance with the water use calculation methods detailed in the Reference Guide. For example, the areas that are partitioned by irrigation type must obviously also take into account sub-areas with specific plant types, microclimates and densities. These sub-areas will have distinct evapotranspiration rates which should be calculated using the appropriate landscape coefficient (KL) for that area. Applicable Internationally.
Campus Applicable
No
Internationally Applicable:
Yes
5/9/2011
LEED Interpretation
Inquiry:
Are calculations based on annual irrigation water use acceptable to earn the credit if it is demonstrated that annual water savings of 50% or greater, due to the use of a weather tracking controller and periods of no irrigation, can be achieved?
Ruling:
Although the strategies used to decrease annual water savings are commendable, the proposed approach is not acceptable. In this credit, all calculations are based on July as a proxy for the peak water demand month. Applicable internationally.
Campus Applicable
No
Internationally Applicable:
Yes
7/1/2016
LEED Interpretation
Inquiry:
Can the EPA Watersense Water Budget Tool be used on 2009 projects? Can EBOM projects use the Option 2 theoretical calculation for Option 1? If so, what are the parameters?
Ruling:
Yes, the EPA Watersense Water Budget Tool can be used for v2009 BD+C and O+M projects. The thresholds in v2009 must still be documented; there is no v4 substitute. The v2009 controller efficiency criteria still holds (e.g. controller efficiency savings are limited to 30%).
EBOM Option 1: projects can use the theoretical calculation from Option 2 to establish the baseline for Option 1. The theoretical baseline case should be calculated using the month of July or the month with the highest irrigation demand and must be compared to metered water use data from that same month. Average values must be used for plant species, density and microclimate factor.
EBOM Option 2: percentage savings can be documented using the Water Budget Tool in place of the theoretical calculations.
EBOM Option 3: the Water Budget Tool can be considered an independent irrigation performance tool. Compare the project's metered water use against the baseline, not the landscape water allowance (LWA).
Campus Applicable
Yes
Internationally Applicable:
Yes
4/1/2012
LEED Interpretation
Inquiry:
The intent of this credit is to alter planting details to eliminate the use of potable water for landscape irrigation as much as possible. Project teams tend to interpret "landscape" as any vegetated space on the project site. However, some projects also include growing space for food in an urban agriculture or community garden setting. This is not "landscape" in the usual sense, and the normal water use reduction measures aren\'t appropriate when the land is being used productively. In LEED for Homes, an existing LEED Interpretation clarifies that growing space should be exempted entirely from the calculations for the Homes version of this credit (do not include in the numerator or denominator). See LI 2736. I request that this LI be extended to all LEED rating systems, since growing space is potentially a component of many project types.
Ruling:
Project teams may elect to exclude food gardens from landscape calculations on the rationale that normal water use reduction measures are not appropriate when the land is being used to produce food for human consumption. If a project team chooses to exclude a food garden from the landscape area, it should be excluded uniformly across the baseline and design calculations.
Campus Applicable
No
Internationally Applicable:
No
LEEDuser expert
Susann Geithner
Dipl. Ing (FH), MSc., LEED AP BD+C, O+M, ID+C, WELL AP
Emerald Built Environments
Principal
