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Credit language
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Requirements
Employ strategies that in aggregate use less water than the water use baseline calculated for the building (not including irrigation). The minimum water savings percentage for each point threshold is as follows:
% Reduction | Points |
---|---|
30% | 2 |
35% | 3 |
40% | 4 |
Commercial Fixtures, Fittings, and Appliances | Current Baseline (Imperial Units) | Current Baseline (Metric units) |
---|---|---|
Commercial Toilets | 1.6 gallons per flush (gpf)* Except blow-out fixtures: 3.5 (gpf) |
6 liters per flush (lpf) Except blow-out fixtures: 13 lpf |
Commercial Urinals | 1.0 (gpf) | 4 lpf |
Commercial Lavatory (Restroom) Faucets | 2.2 gallons per minute (gpm) at 60 pounds per square inch (psi), private applications only (hotel or motel guest rooms, hospital patient rooms) 0.5 (gpm) at 60 (psi)** all others except private applications 0.25 gallons per cycle for metering faucets |
8.5 liters per minute (lpm) at 4 bar (58 psi), private applications only (hotel or motel guest rooms, hospital patient rooms) 2.0 lpm at 4 bar (58 psi), all others except private applications 1 liter per cycle for metering faucets |
Showerheads | 2.5 (gpm) at 80 (psi) per shower stall **** | 9.5 lpm at 5 bar (58 psi) |
For projects with commercial pre-rinse spray valves, the flow rate must comply with the asME a112.18.1 standard of 1.6 gpm or less. |
Residential fixtures, fittings, and appliances | Current baseline (imperial units) | Current baseline (metric units) |
---|---|---|
Residential toilets | 1.6 (gpf)*** | 6 liters per flush (lpf) Except blow-out fixtures: 13 lpf |
Residential lavatory (bathroom) faucets | 2.2 (gpm) at 60 psi | 4 lpm 8.5 lpm at 4 bar (58 psi), private applications only (hotel or motel guest rooms, hospital patient rooms) 2.0 lpm at 4 bar (58 psi), all others except private applications 1 liter per cycle for metering faucets |
Residential kitchen faucet | ||
Residential showerheads | 2.5 (gpm) at 80 (psi) per shower stall**** | flow rate ≤ 6.1 lpm (no pressure specified; no performance requirement) |
* EPAct1992 standard for toilets applies to both commercial and residential models. ** in addition to Epact requirements, the american society of Mechanical Engineers standard for public lavatory faucets is 0.5 gpm at 60 psi (2.0 lpm at 4 bar (58 psi)) (asME a112.18.1-2005). this maximum has been incorporated into the national uniform plumbing Code and the international plumbing Code. *** EPAct 1992 standard for toilets applies to both commercial and residential models. **** residential shower compartment (stall) in dwelling units: the total allowable flow rate from all flowing showerheads at any given time, including rain systems, waterfalls, bodysprays, bodyspas and jets, must be limited to the allowable showerhead flow rate as specified above (2.5 gpm) per shower compartment, where the floor area of the shower compartment is less than 2,500 square inches (1.5 square meters). for each increment of 2,500 square inches (1.5 square meters) of floor area thereafter or part thereof, an additional showerhead with total allowable flow rate from all flowing devices equal to or less than the allowable flow rate as specified above must be allowed. Exception: showers that emit recirculated nonpotable water originating from within the shower compartment while operating are allowed to exceed the maximum as long as the total potable water flow does not exceed the flow rate as specified above. |
- Commercial Steam Cookers
- Commercial Dishwashers
- Automatic Commercial Ice Makers
- Commercial (family-sized) Clothes Washers
- Residential Clothes Washers
- Standard and Compact Residential Dishwashers
Alternative Compliance Paths (ACPs)
Europe ACP: Water Use Baseline
Projects in Europe may use the values defined by European Standards. [view:embed_resource=page_1=4887966] See all forum discussions about this credit »What does it cost?
Cost estimates for this credit
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Learn more about The Cost of LEED v4 »Frequently asked questions
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We provided new showers in our project to comply with the alternative transportation credit. Should they be considered in WEp1 calculations? 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.) |
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Our project is a factory with historically a 95% male workforce. The restroom design accounts for this. Can I argue that the male/female gender ratio is different than 50/50?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.) |
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Addenda
Add the following to eligible fixtures section:
"For healthcare projects, fixtures used for clinical use related to medical procedures, such as surgical scrub sinks and exam rooms sinks, in hospitals and medical office buildings are excluded from the water use calculations. Medication room sinks, utility room sinks, and other exam/procedure/observation room sinks for clinical use are also excluded. Should exam/procedure/observation room sinks be used primarily for hand-washing, they may be included in the water use calculations at the project team’s discretion under the public lavatory category. If included, project teams should provide a narrative explaining the usage assumptions for these sinks.
Lavatories in hospital inpatient bathrooms and inpatient rooms are considered private. The inpatient lavatory and water closet should use the default residential usage assumptions (of five times per day per residential occupant), unless specific project conditions warrant an alternative. Lavatories in hospital inpatient rooms (outside the bathrooms) are considered private if used by patients and/or staff similarly to a residential lavatory, or can be exempt if they are used by staff primarily for medical or clinical use.
Nutrition station (pantry) sinks and hospital staff lounge sinks should be included in the water use calculations under the kitchen sink category."
This is an inquiry about the calculation of the FTE in relation to our project in Zurich, Switzerland. In the LEED Reference Guide on page 53 the calculation of the FTE is based on a 8-hour working day. That means that an 8-hour occupant has an FTE value of 1.0. The standard working day in Switzerland contains 8.5 hours of work.In a FTE calculation on the basis that is provided in the LEED Reference Guide the normal working day of one single person would have the FTE value of 1.0625. As a consequence of the, in case of 1000 people fulltime staff this FTE calculation would have additional number of 63 FTE in comparion to an FTE value of 1.0.Is it possible to calculate the FTE value for this project with an 8.5 instead of 8 hour day, so that we would have the FTE value of 1.0 for a standard 8.5 hour-working day?
The project team has inquired if projects in Switzerland may use 8.5-hours as their working day instead of 8-hours as in the US. Each full-time employee based on Swiss and US labor laws works an 8.5-hour day, which includes a half-hour unpaid lunch break and two 15-minute paid breaks. In order to maintain the baseline for projects everywhere when calculating FTE occupancy, all Swiss projects, including those industries that have an overtime work culture for full-time employees, should still use the 8.0-hour work day in their FTE calculations. Applicable internationally.
Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?
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
Should prison fixtures be included or excluded from WEp1 and WEc3 (WEc1 in CI) Water Use Reduction calculations?
Beginning with projects registered after 7/1/2012, prison water closets (toilets), urinals and safety showerheads must be included in water use reduction calculations for fixtures and fittings. This LI overturns the older LI 5033 (applicable to projects registered before 11/1/2011) and expands on the language of LI 10120 (applicable to projects registered between 11/1/2011 and 7/1/2012). Fixture use assumptions for prisoners follow the default fixture assumptions for residential occupants. Accordingly, lavatory faucets, toilets, and showerheads serving prisoners must follow the residential fixture requirements, baselines, and daily usage assumptions for the purposes of this prerequisite/credit. Internationally applicable.***Update 1/1/13: This LI is applicable to LEED NC v2.2
Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?
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.
10/1/13 notes: link resource and edit ruling: 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.
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 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."
Are swimming pools excluded from the calculations for WE Prerequisite 1?
This is correct as the prerequisite only covers fixtures specified in the Reference Guide and regulated by one of the standards listed. These fixtures and fixture fittings include water closets, urinals, lavatory faucets, showers, kitchen sink facets, and pre-rinse spray valves. Applicable internationally.
Can a LEED-NC project without eligible water fixtures be exempt from WEp1 Water Use Reduction?
A project without eligible water fixtures in the LEED-NC project boundary is exempt from WEp1. Should such a project wish to pursue points under WE Credit 3, they may do so by evaluating WEc3 performance based upon all of the fixtures that are necessary to meet the needs of the project occupants, even if they are located outside the project boundary.
**Update October 1, 2012: Has been made applicable to LEED for Schools v2007 and v2009.
**Update October 1, 2013: Applicable credits were updated. This ruling does not apply to Core and Shell projects.
Can children\'s toilets be exempt from the prerequisite because there are no low-flow options available?
There are children\'s toilets available that are 1.6 gpf. The project team must decide what is best for the clientele, but baby toilets cannot be exempt from the credit. Applicable internationally.
We are currently designing a new County Justice Center. The project consists of 193,338 gsf and will house the county jail, Courts and office space for the County Attorney, Community Corrections, Sheriff and Court Administration. The facility comprises an occupant load of 1,879 - 587 of which are attributable to the jail portion of the facility including the inmate population, staff and visitors. During the design development process, the project team has determined that the project will be able to achieve over 40% water efficiency for the project in the courts and office space of the project. However, due to the product availability, maintenance requirements and the behavioral nature of the inmate population we have determined that the project will be unable to use low flow fixtures for the jail portion of the building. Use of low flow fixtures will place an unreasonable burden on the construction project and negatively impact the ongoing operations and maintenance of the project. Not being able to use these fixture types will negate the water efficiency achieved in other portions of the building. We respectfully request that the jail portion of the facility be exempt from the water efficiency calculations and that these strategies be applied only to the Courts and Offices areas of the project.
In the definitions section of EPAct 1992 (Section 123, B) "water closet" and "urinal" fixtures installed in prisons are excluded. Also, the definition of "showerhead" excludes safety showerheads. Thus, these fixtures do not fall in the scope of this credit, and do not need to be included in the calculations for WEc3. Applicable Internationally.***This LI has been overturned by LI 10120, for projects registered after 11/1/2011, and LI 10216, for projects registered after 7/1/2012***Update 1/1/13: This LI has been made applicable to LEED NC v2.0, v2.2, and Schools v2007.
Does a single-occupant lockable bathroom in a commercial establishment count as "private" for flush & flow rate calculations?
The project team is requesting a ruling on whether restrooms at a commercial establishment that are only usable by one individual or family at a time are considered private or private-use facilities. The facilities that are usable by one individual or family at a time at a commercial establishment are not considered private or private-use facilities. The private or public categories for lavatory faucets are based on the UPC and IPC Standards for plumbing fixtures, and are referring to the anticipated uses and performance expectations of such faucets. Public restroom faucets are used almost exclusively for hand washing or simple rinsing, compared to lavatory faucets in homes and in other private bathrooms that are used for various purposes. Therefore the single occupancy restroom facilities at a commercial establishment are not private-use facilities and the baseline case must be calculated according to the public lavatory faucet baseline flow rate. Applicable internationally.
The installation of bedside patient care units, which is a combined toilet and lavatory, is required for some patient rooms. Can the patient care unit be excluded from the calculations since there are no low-flow options available?
All fixtures that are covered by the EPAct 1992 must be included in the credit calculations, even if there are no low-flow options available. The use of these fixtures by only the patients in a limited area can be factored into the calculations.
Can the jail portion of a prison facility be excluded from the water efficient toilet requirements of this credit due to the lack of product availability, maintenance requirements and the behavioral nature of the inmate population?
There are now a sufficient number of stainless steel jail type toilets on the market at the 1.28 gpf level or below to make compliance with this prerequisite reasonable. Therefore, the jail portion of a prison facility is not exempt from the credit baseline and design calculations for LEED 2009 projects. Applicable Internationally.***This LI overturns LI 5033, for projects registered after 11/1/2011, and projects registered after 7/1/2012 must refer to LI 10216, which provides additional clarifications on this issue.***Update 1/1/13: This LI is applicable to LEED NC v2.2
We are seeking clarification on the use of municipally provided non-potable water for achieving WEc3 under the LEED NC version 2.2 rating system. Use of municipally supplied non-potable water meets the intent of limiting or eliminating the use of potable water and reduces the burden on municipal water supplies. However, currently, the Reference Guide does not give clear direction with concern to WEc1, WEc2 & WEc3 and municipally supplied water: WEc1 states that water savings can be claimed through the use of "water treated and conveyed by a public agency specifically for non-potable uses." WEc2 states that water savings can be claimed through the use of "municipally treated wastewater." WEc3, however, makes no statements as to whether municipally supplied recycled water can count towards water saving calculations. However, the synergies between WEc2 and WEc3 calculations leads one to conclude that municipally supplied wastewater can be used for both credit calculations. Our project will be using municipally supplied non-potable reclaimed water for both irrigation and sewage conveyance (toilet flushing). Can you please clarify whether municipally supplied reclaimed water can be used to achieve both WEc3.1 and WEc3.2?
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 10, 2006
Municipally reclaimed water is not applicable to WEc3 achievement. This credit focuses on fixture efficiency and on-site water reuse. Applicable Internationally.
Should prison fixtures be included or excluded from WEp1 and WEc3 (WEc1 in CI) Water Use Reduction calculations?
Beginning with projects registered after 7/1/2012, prison water closets (toilets), urinals and safety showerheads must be included in water use reduction calculations for fixtures and fittings. This LI overturns the older LI 5033 (applicable to projects registered before 11/1/2011) and expands on the language of LI 10120 (applicable to projects registered between 11/1/2011 and 7/1/2012). Fixture use assumptions for prisoners follow the default fixture assumptions for residential occupants. Accordingly, lavatory faucets, toilets, and showerheads serving prisoners must follow the residential fixture requirements, baselines, and daily usage assumptions for the purposes of this prerequisite/credit. Internationally applicable. Internationally applicable.***Update 1/1/13: This LI is applicable to LEED NC v2.2
For campus projects, can wastewater treatment facilities located outside of the LEED project boundary but within the campus boundary qualify as on-site for the purposes of this credit?
"Update October 20, 2016: Campus projects may continue to utilize a wastewater treatment facility located outside of the LEED project boundary as long as it is within the campus boundary for Option 2 in WEc2: Innovative Wastewater Technologies. Treated water must be infiltrated or used on-site by the project. The only change to this ruling is that the campus treated wastewater can also apply in WEc3: Water Use Reduction, if reused in the project’s flush fixtures. See the updated “Water Use Reduction Additional Guidance” document.
Original ruling April 1, 2013:
Yes, campus projects may utilize a wastewater treatment facility located outside of the LEED project boundary as long as it is within the campus boundary for Option 2. Treated water must be infiltrated or used on-site by the project.
Please note that a campus scale wastewater treatment facility located outside of the LEED project boundary would be considered a municipally supplied non-potable water source for all other Water Efficiency credits, and would not be considered an on-site non-potable water source in WEp1 Water Use Reduction. Applicable Internationally."
Can untreated groundwater, unsuitable for drinking, contribute towards WE credits 1, 2, and 3 as a non-potable water source for irrigation and sewage conveyance?
This approach does not meet the intent of the WE credits. Although the local groundwater may not be suitable for drinking straight out of the ground, it still represents an important source of potable water. Applicable internationally.
Our project is an Army standard Company Operations Facility (COF) which consists of office and warehouse modules. The Army standard design for this building type requires both the office and warehouse modules, and while these components are typically combined under one roof, the standard allows for a detached configuration based on site conditions and user preference. For this project, the detached configuration will be used with a conditioned warehouse module detached from (but adjacent to) the office module. In accordance with the Army Standard for COF facilities, the warehouse module is not permitted to have restroom facilities since they are provided in the office module and the Army mandates the consolidation of plumbing fixtures in one location. The absence of dedicated toilets or fixtures in the warehouse module may prevent it from meeting the Water Efficiency prerequisite 1 under LEED NC if registered as a standalone building. Can the separate office and warehouse modules for this project be registered as one building?
UPDATE 10/1/2012 - This Ruling has been retracted because it is project-specific. It is no longer applicable as of 10/01/2012. It can only be used by Army standard Company Operations Facilities projects registered or submitted for review between 7/1/12 and 8/30/12. Similar project types will be evaluated on a case by case basis.The project team is inquiring if the Army standard Company Operations Facility (COF) which consists of office and warehouse modules can be considered a single building even for instances where the components may be detached. Yes, the Company Operations Facility can be considered a single building. The fact that the components of the COF are tied together and only a single set of plumbing fixtures is provided between the components indicates that they operate as a single building even when detached.
Can reverse osmosis reject water be used as an innovative wastewater source? Reverse osmosis water is often used in lab, hospital and other process water settings.
Yes, on-site reverse osmosis reject water is an acceptable non-potable water source. Applicable internationally.
Summary: Interpretation ruling pertaining to establishing the calculation baseline for Water Reduction Credits 3.1 & 3.2 when on-site tests have been conducted, and demonstrate that the supply water pressure levels (psi) to the fixtures are substantially below the 80 psi referenced within the Energy Policy Act of 1992. Context: The scope of the project incorporates new construction of four residential halls on a college campus, which house more than 250 students and staff. Three of the buildings are three stories, and the other is four stories. Description: The residence halls are incorporating a range of fixtures that are below the flow rates within the Energy Policy Act of 1992 (dual flush toilets, and faucets within the kitchens, kitchenettes, bathrooms & apartments). The showers in the residence hall are the largest water consumer (by a large %) within the residence hall buildings. To begin to understand the water amount actually used on the project, the owner conducted some initial on-site tests to determine the supply pressure to the plumbing fixtures, and how that translated into the actual flow. On-site tests for one of the buildings have been conducted on the flow rates of the shower heads with the following results: Fixture type currently installed = 2.5 gpm 1st floor: 52 psi static, 2.10 gpm 2nd floor: 46 psi static, 1.92 gpm 3rd floor: 41 psi static, 1.79 gpm 4th floor: 37 psi static, 1.85 gpm Question: o Would the design case account for the lower psi (reduced water use) by multiplying the \'Water Use\' column within the calculation template by the percentage of supply/baseline? For example for a shower on the first floor the \'Water Use" would be multiplied by 65% (52/80) or by just including 2.10 gpm as the flow rate for the fixture on this floor? o What is the appropriate methodology for establishing the calculation baseline when the water pressure supply rate (psi) is substantially lower than the 80 psi outlined as the baseline flow rates under the Energy Policy Act of 1992?
[Note: this ruling was revised on 9/1/04.] The underlying assumptions used for calculating projected water use savings should remain consistent between the baseline and design case. Supply water pressure varies across the United States and within individual buildings (as you note in your inquiry). Flow rates at 80 psi are used for the calculations in this credit for consistency and to reward use of efficient fixtures. It is recommended that all projects use the flow rates reported by the manufacturer at 80 psi for comparison with the Energy Policy Act of 1992 flow rates. If you wish to use on-site tests to report the most accurate volume of water use, you must be consistent throughout all fixtures and test both baseline and design fixtures. It is not acceptable to use flow rates at 80 psi for some fixtures and actual flow rates for other fixtures. Measurement can also be used to account for the benefits of whole-building strategies, e.g., flow restrictors at the water service entrance. Applicable Internationally.
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Requirements
Employ strategies that in aggregate use less water than the water use baseline calculated for the building (not including irrigation). The minimum water savings percentage for each point threshold is as follows:
% Reduction | Points |
---|---|
30% | 2 |
35% | 3 |
40% | 4 |
Commercial Fixtures, Fittings, and Appliances | Current Baseline (Imperial Units) | Current Baseline (Metric units) |
---|---|---|
Commercial Toilets | 1.6 gallons per flush (gpf)* Except blow-out fixtures: 3.5 (gpf) |
6 liters per flush (lpf) Except blow-out fixtures: 13 lpf |
Commercial Urinals | 1.0 (gpf) | 4 lpf |
Commercial Lavatory (Restroom) Faucets | 2.2 gallons per minute (gpm) at 60 pounds per square inch (psi), private applications only (hotel or motel guest rooms, hospital patient rooms) 0.5 (gpm) at 60 (psi)** all others except private applications 0.25 gallons per cycle for metering faucets |
8.5 liters per minute (lpm) at 4 bar (58 psi), private applications only (hotel or motel guest rooms, hospital patient rooms) 2.0 lpm at 4 bar (58 psi), all others except private applications 1 liter per cycle for metering faucets |
Showerheads | 2.5 (gpm) at 80 (psi) per shower stall **** | 9.5 lpm at 5 bar (58 psi) |
For projects with commercial pre-rinse spray valves, the flow rate must comply with the asME a112.18.1 standard of 1.6 gpm or less. |
Residential fixtures, fittings, and appliances | Current baseline (imperial units) | Current baseline (metric units) |
---|---|---|
Residential toilets | 1.6 (gpf)*** | 6 liters per flush (lpf) Except blow-out fixtures: 13 lpf |
Residential lavatory (bathroom) faucets | 2.2 (gpm) at 60 psi | 4 lpm 8.5 lpm at 4 bar (58 psi), private applications only (hotel or motel guest rooms, hospital patient rooms) 2.0 lpm at 4 bar (58 psi), all others except private applications 1 liter per cycle for metering faucets |
Residential kitchen faucet | ||
Residential showerheads | 2.5 (gpm) at 80 (psi) per shower stall**** | flow rate ≤ 6.1 lpm (no pressure specified; no performance requirement) |
* EPAct1992 standard for toilets applies to both commercial and residential models. ** in addition to Epact requirements, the american society of Mechanical Engineers standard for public lavatory faucets is 0.5 gpm at 60 psi (2.0 lpm at 4 bar (58 psi)) (asME a112.18.1-2005). this maximum has been incorporated into the national uniform plumbing Code and the international plumbing Code. *** EPAct 1992 standard for toilets applies to both commercial and residential models. **** residential shower compartment (stall) in dwelling units: the total allowable flow rate from all flowing showerheads at any given time, including rain systems, waterfalls, bodysprays, bodyspas and jets, must be limited to the allowable showerhead flow rate as specified above (2.5 gpm) per shower compartment, where the floor area of the shower compartment is less than 2,500 square inches (1.5 square meters). for each increment of 2,500 square inches (1.5 square meters) of floor area thereafter or part thereof, an additional showerhead with total allowable flow rate from all flowing devices equal to or less than the allowable flow rate as specified above must be allowed. Exception: showers that emit recirculated nonpotable water originating from within the shower compartment while operating are allowed to exceed the maximum as long as the total potable water flow does not exceed the flow rate as specified above. |
- Commercial Steam Cookers
- Commercial Dishwashers
- Automatic Commercial Ice Makers
- Commercial (family-sized) Clothes Washers
- Residential Clothes Washers
- Standard and Compact Residential Dishwashers
Alternative Compliance Paths (ACPs)
Europe ACP: Water Use Baseline
Projects in Europe may use the values defined by European Standards. [view:embed_resource=page_1=4887966]XX%
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Add the following to eligible fixtures section:
"For healthcare projects, fixtures used for clinical use related to medical procedures, such as surgical scrub sinks and exam rooms sinks, in hospitals and medical office buildings are excluded from the water use calculations. Medication room sinks, utility room sinks, and other exam/procedure/observation room sinks for clinical use are also excluded. Should exam/procedure/observation room sinks be used primarily for hand-washing, they may be included in the water use calculations at the project team’s discretion under the public lavatory category. If included, project teams should provide a narrative explaining the usage assumptions for these sinks.
Lavatories in hospital inpatient bathrooms and inpatient rooms are considered private. The inpatient lavatory and water closet should use the default residential usage assumptions (of five times per day per residential occupant), unless specific project conditions warrant an alternative. Lavatories in hospital inpatient rooms (outside the bathrooms) are considered private if used by patients and/or staff similarly to a residential lavatory, or can be exempt if they are used by staff primarily for medical or clinical use.
Nutrition station (pantry) sinks and hospital staff lounge sinks should be included in the water use calculations under the kitchen sink category."
This is an inquiry about the calculation of the FTE in relation to our project in Zurich, Switzerland. In the LEED Reference Guide on page 53 the calculation of the FTE is based on a 8-hour working day. That means that an 8-hour occupant has an FTE value of 1.0. The standard working day in Switzerland contains 8.5 hours of work.In a FTE calculation on the basis that is provided in the LEED Reference Guide the normal working day of one single person would have the FTE value of 1.0625. As a consequence of the, in case of 1000 people fulltime staff this FTE calculation would have additional number of 63 FTE in comparion to an FTE value of 1.0.Is it possible to calculate the FTE value for this project with an 8.5 instead of 8 hour day, so that we would have the FTE value of 1.0 for a standard 8.5 hour-working day?
The project team has inquired if projects in Switzerland may use 8.5-hours as their working day instead of 8-hours as in the US. Each full-time employee based on Swiss and US labor laws works an 8.5-hour day, which includes a half-hour unpaid lunch break and two 15-minute paid breaks. In order to maintain the baseline for projects everywhere when calculating FTE occupancy, all Swiss projects, including those industries that have an overtime work culture for full-time employees, should still use the 8.0-hour work day in their FTE calculations. Applicable internationally.
Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?
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
Should prison fixtures be included or excluded from WEp1 and WEc3 (WEc1 in CI) Water Use Reduction calculations?
Beginning with projects registered after 7/1/2012, prison water closets (toilets), urinals and safety showerheads must be included in water use reduction calculations for fixtures and fittings. This LI overturns the older LI 5033 (applicable to projects registered before 11/1/2011) and expands on the language of LI 10120 (applicable to projects registered between 11/1/2011 and 7/1/2012). Fixture use assumptions for prisoners follow the default fixture assumptions for residential occupants. Accordingly, lavatory faucets, toilets, and showerheads serving prisoners must follow the residential fixture requirements, baselines, and daily usage assumptions for the purposes of this prerequisite/credit. Internationally applicable.***Update 1/1/13: This LI is applicable to LEED NC v2.2
Can municipally supplied treated seawater for toilet flushing be used as a strategy for earning WEp1 and WEc1 Water Use Reduction?
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.
10/1/13 notes: link resource and edit ruling: 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.
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 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."
Are swimming pools excluded from the calculations for WE Prerequisite 1?
This is correct as the prerequisite only covers fixtures specified in the Reference Guide and regulated by one of the standards listed. These fixtures and fixture fittings include water closets, urinals, lavatory faucets, showers, kitchen sink facets, and pre-rinse spray valves. Applicable internationally.
Can a LEED-NC project without eligible water fixtures be exempt from WEp1 Water Use Reduction?
A project without eligible water fixtures in the LEED-NC project boundary is exempt from WEp1. Should such a project wish to pursue points under WE Credit 3, they may do so by evaluating WEc3 performance based upon all of the fixtures that are necessary to meet the needs of the project occupants, even if they are located outside the project boundary.
**Update October 1, 2012: Has been made applicable to LEED for Schools v2007 and v2009.
**Update October 1, 2013: Applicable credits were updated. This ruling does not apply to Core and Shell projects.
Can children\'s toilets be exempt from the prerequisite because there are no low-flow options available?
There are children\'s toilets available that are 1.6 gpf. The project team must decide what is best for the clientele, but baby toilets cannot be exempt from the credit. Applicable internationally.
We are currently designing a new County Justice Center. The project consists of 193,338 gsf and will house the county jail, Courts and office space for the County Attorney, Community Corrections, Sheriff and Court Administration. The facility comprises an occupant load of 1,879 - 587 of which are attributable to the jail portion of the facility including the inmate population, staff and visitors. During the design development process, the project team has determined that the project will be able to achieve over 40% water efficiency for the project in the courts and office space of the project. However, due to the product availability, maintenance requirements and the behavioral nature of the inmate population we have determined that the project will be unable to use low flow fixtures for the jail portion of the building. Use of low flow fixtures will place an unreasonable burden on the construction project and negatively impact the ongoing operations and maintenance of the project. Not being able to use these fixture types will negate the water efficiency achieved in other portions of the building. We respectfully request that the jail portion of the facility be exempt from the water efficiency calculations and that these strategies be applied only to the Courts and Offices areas of the project.
In the definitions section of EPAct 1992 (Section 123, B) "water closet" and "urinal" fixtures installed in prisons are excluded. Also, the definition of "showerhead" excludes safety showerheads. Thus, these fixtures do not fall in the scope of this credit, and do not need to be included in the calculations for WEc3. Applicable Internationally.***This LI has been overturned by LI 10120, for projects registered after 11/1/2011, and LI 10216, for projects registered after 7/1/2012***Update 1/1/13: This LI has been made applicable to LEED NC v2.0, v2.2, and Schools v2007.
Does a single-occupant lockable bathroom in a commercial establishment count as "private" for flush & flow rate calculations?
The project team is requesting a ruling on whether restrooms at a commercial establishment that are only usable by one individual or family at a time are considered private or private-use facilities. The facilities that are usable by one individual or family at a time at a commercial establishment are not considered private or private-use facilities. The private or public categories for lavatory faucets are based on the UPC and IPC Standards for plumbing fixtures, and are referring to the anticipated uses and performance expectations of such faucets. Public restroom faucets are used almost exclusively for hand washing or simple rinsing, compared to lavatory faucets in homes and in other private bathrooms that are used for various purposes. Therefore the single occupancy restroom facilities at a commercial establishment are not private-use facilities and the baseline case must be calculated according to the public lavatory faucet baseline flow rate. Applicable internationally.
The installation of bedside patient care units, which is a combined toilet and lavatory, is required for some patient rooms. Can the patient care unit be excluded from the calculations since there are no low-flow options available?
All fixtures that are covered by the EPAct 1992 must be included in the credit calculations, even if there are no low-flow options available. The use of these fixtures by only the patients in a limited area can be factored into the calculations.
Can the jail portion of a prison facility be excluded from the water efficient toilet requirements of this credit due to the lack of product availability, maintenance requirements and the behavioral nature of the inmate population?
There are now a sufficient number of stainless steel jail type toilets on the market at the 1.28 gpf level or below to make compliance with this prerequisite reasonable. Therefore, the jail portion of a prison facility is not exempt from the credit baseline and design calculations for LEED 2009 projects. Applicable Internationally.***This LI overturns LI 5033, for projects registered after 11/1/2011, and projects registered after 7/1/2012 must refer to LI 10216, which provides additional clarifications on this issue.***Update 1/1/13: This LI is applicable to LEED NC v2.2
We are seeking clarification on the use of municipally provided non-potable water for achieving WEc3 under the LEED NC version 2.2 rating system. Use of municipally supplied non-potable water meets the intent of limiting or eliminating the use of potable water and reduces the burden on municipal water supplies. However, currently, the Reference Guide does not give clear direction with concern to WEc1, WEc2 & WEc3 and municipally supplied water: WEc1 states that water savings can be claimed through the use of "water treated and conveyed by a public agency specifically for non-potable uses." WEc2 states that water savings can be claimed through the use of "municipally treated wastewater." WEc3, however, makes no statements as to whether municipally supplied recycled water can count towards water saving calculations. However, the synergies between WEc2 and WEc3 calculations leads one to conclude that municipally supplied wastewater can be used for both credit calculations. Our project will be using municipally supplied non-potable reclaimed water for both irrigation and sewage conveyance (toilet flushing). Can you please clarify whether municipally supplied reclaimed water can be used to achieve both WEc3.1 and WEc3.2?
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 10, 2006
Municipally reclaimed water is not applicable to WEc3 achievement. This credit focuses on fixture efficiency and on-site water reuse. Applicable Internationally.
Should prison fixtures be included or excluded from WEp1 and WEc3 (WEc1 in CI) Water Use Reduction calculations?
Beginning with projects registered after 7/1/2012, prison water closets (toilets), urinals and safety showerheads must be included in water use reduction calculations for fixtures and fittings. This LI overturns the older LI 5033 (applicable to projects registered before 11/1/2011) and expands on the language of LI 10120 (applicable to projects registered between 11/1/2011 and 7/1/2012). Fixture use assumptions for prisoners follow the default fixture assumptions for residential occupants. Accordingly, lavatory faucets, toilets, and showerheads serving prisoners must follow the residential fixture requirements, baselines, and daily usage assumptions for the purposes of this prerequisite/credit. Internationally applicable. Internationally applicable.***Update 1/1/13: This LI is applicable to LEED NC v2.2
For campus projects, can wastewater treatment facilities located outside of the LEED project boundary but within the campus boundary qualify as on-site for the purposes of this credit?
"Update October 20, 2016: Campus projects may continue to utilize a wastewater treatment facility located outside of the LEED project boundary as long as it is within the campus boundary for Option 2 in WEc2: Innovative Wastewater Technologies. Treated water must be infiltrated or used on-site by the project. The only change to this ruling is that the campus treated wastewater can also apply in WEc3: Water Use Reduction, if reused in the project’s flush fixtures. See the updated “Water Use Reduction Additional Guidance” document.
Original ruling April 1, 2013:
Yes, campus projects may utilize a wastewater treatment facility located outside of the LEED project boundary as long as it is within the campus boundary for Option 2. Treated water must be infiltrated or used on-site by the project.
Please note that a campus scale wastewater treatment facility located outside of the LEED project boundary would be considered a municipally supplied non-potable water source for all other Water Efficiency credits, and would not be considered an on-site non-potable water source in WEp1 Water Use Reduction. Applicable Internationally."
Can untreated groundwater, unsuitable for drinking, contribute towards WE credits 1, 2, and 3 as a non-potable water source for irrigation and sewage conveyance?
This approach does not meet the intent of the WE credits. Although the local groundwater may not be suitable for drinking straight out of the ground, it still represents an important source of potable water. Applicable internationally.
Our project is an Army standard Company Operations Facility (COF) which consists of office and warehouse modules. The Army standard design for this building type requires both the office and warehouse modules, and while these components are typically combined under one roof, the standard allows for a detached configuration based on site conditions and user preference. For this project, the detached configuration will be used with a conditioned warehouse module detached from (but adjacent to) the office module. In accordance with the Army Standard for COF facilities, the warehouse module is not permitted to have restroom facilities since they are provided in the office module and the Army mandates the consolidation of plumbing fixtures in one location. The absence of dedicated toilets or fixtures in the warehouse module may prevent it from meeting the Water Efficiency prerequisite 1 under LEED NC if registered as a standalone building. Can the separate office and warehouse modules for this project be registered as one building?
UPDATE 10/1/2012 - This Ruling has been retracted because it is project-specific. It is no longer applicable as of 10/01/2012. It can only be used by Army standard Company Operations Facilities projects registered or submitted for review between 7/1/12 and 8/30/12. Similar project types will be evaluated on a case by case basis.The project team is inquiring if the Army standard Company Operations Facility (COF) which consists of office and warehouse modules can be considered a single building even for instances where the components may be detached. Yes, the Company Operations Facility can be considered a single building. The fact that the components of the COF are tied together and only a single set of plumbing fixtures is provided between the components indicates that they operate as a single building even when detached.
Can reverse osmosis reject water be used as an innovative wastewater source? Reverse osmosis water is often used in lab, hospital and other process water settings.
Yes, on-site reverse osmosis reject water is an acceptable non-potable water source. Applicable internationally.
Summary: Interpretation ruling pertaining to establishing the calculation baseline for Water Reduction Credits 3.1 & 3.2 when on-site tests have been conducted, and demonstrate that the supply water pressure levels (psi) to the fixtures are substantially below the 80 psi referenced within the Energy Policy Act of 1992. Context: The scope of the project incorporates new construction of four residential halls on a college campus, which house more than 250 students and staff. Three of the buildings are three stories, and the other is four stories. Description: The residence halls are incorporating a range of fixtures that are below the flow rates within the Energy Policy Act of 1992 (dual flush toilets, and faucets within the kitchens, kitchenettes, bathrooms & apartments). The showers in the residence hall are the largest water consumer (by a large %) within the residence hall buildings. To begin to understand the water amount actually used on the project, the owner conducted some initial on-site tests to determine the supply pressure to the plumbing fixtures, and how that translated into the actual flow. On-site tests for one of the buildings have been conducted on the flow rates of the shower heads with the following results: Fixture type currently installed = 2.5 gpm 1st floor: 52 psi static, 2.10 gpm 2nd floor: 46 psi static, 1.92 gpm 3rd floor: 41 psi static, 1.79 gpm 4th floor: 37 psi static, 1.85 gpm Question: o Would the design case account for the lower psi (reduced water use) by multiplying the \'Water Use\' column within the calculation template by the percentage of supply/baseline? For example for a shower on the first floor the \'Water Use" would be multiplied by 65% (52/80) or by just including 2.10 gpm as the flow rate for the fixture on this floor? o What is the appropriate methodology for establishing the calculation baseline when the water pressure supply rate (psi) is substantially lower than the 80 psi outlined as the baseline flow rates under the Energy Policy Act of 1992?
[Note: this ruling was revised on 9/1/04.] The underlying assumptions used for calculating projected water use savings should remain consistent between the baseline and design case. Supply water pressure varies across the United States and within individual buildings (as you note in your inquiry). Flow rates at 80 psi are used for the calculations in this credit for consistency and to reward use of efficient fixtures. It is recommended that all projects use the flow rates reported by the manufacturer at 80 psi for comparison with the Energy Policy Act of 1992 flow rates. If you wish to use on-site tests to report the most accurate volume of water use, you must be consistent throughout all fixtures and test both baseline and design fixtures. It is not acceptable to use flow rates at 80 psi for some fixtures and actual flow rates for other fixtures. Measurement can also be used to account for the benefits of whole-building strategies, e.g., flow restrictors at the water service entrance. Applicable Internationally.