The links below contain guidelines for achieving each goal, including recommended processes for each design phase.
* Regional Priority (RP) credit for the following zip codes: 02134 (Allston, MA), 02138, 02139 (Cambridge, MA)
WE Prerequisite 1: Water Use Reduction
WE Prerequisite 1 ROADMAP
| Design Phase | Recommended Approach: Activities | Recommended Approach: Responsibilities |
|---|---|---|
| Pre-Design | Set the goal of at least a 40% potable water reduction. | Client |
| Conceptual Design | Review WEp1 requirements. Calculate baseline water use based on FTE count and EPAct of 1992 requirements. Calculate the design case with fixtures that exceed EPAct of 1992 requirements. | Engineers |
| Schematic through Construction Documents | Calculate design use for sewage conveyance. Include water-efficient plumbing fixture requirements in the project specifications. Specify dual-flush toilets, low-flow lavatories with automatic faucets, and waterless urinals. If applicable, specify water-efficient kitchen dishwashers or washing machines. Consider composting toilets. See the Technologies & Products section for products and systems used at Harvard. | Engineers |
| Schematic Design | Consider using rainwater for flushing toilets. A dual-plumbing system is necessary for greywater reuse. Identify the amount of water that could be collected from interior greywater, or stormwater, for flushing toilets. | Architect/Engineers |
| Construction Documents | Complete LEED Online Letter Template and provide submittal requirements. | Engineers or OFS |
| Construction Documents to Construction | Ensure dual-flush toilets, low-flow lavatories with automatic faucets, and waterless urinals are specified. Ensure submittals are reviewed and approved per the specifications requirements. | Engineers |
| Construction Documents | This credit is a Design Submittal and should be submitted to the USGBC after construction documents are complete. | OFS or LEED Consultant |
| Construction | Review Contractor submittals to ensure that water efficient fixtures are selected. | Engineers |
Design Intent and Sustainability Principles
Potable water is a limited natural resource, and increasing water efficiency in buildings conserves this resource and reduces the burden on municipal water supply and wastewater systems.
Financial Considerations
Water-saving fixtures, such as dual-flush toilets, waterless urinals, low-flow faucets and showerheads are comparable in price to standard fixtures, and have been used in numerous Harvard buildings. See the Technologies & Products section for more details.
LEED Requirements
See updated Credit Interpretation Rulings issued by the U.S. Green Building Council.
LEED-CI Version 3
"Employ strategies that in aggregate use 20% less water than the water use baseline calculated for the building (not including irrigation).
Calculate the baseline according to the commercial and/or residential baselines outlined below.1 Calculations are based on estimated occupant usage and must include only the following fixtures and fixture fittings (as applicable to the project scope): water closets, urinals, lavatory faucets, showers, kitchen sink faucets and prerinse spray valves.
| Commercial Fixtures, Fittings, and Appliances | Current Baseline |
|---|---|
| Commercial toilets | 1.6 gallons per flush (gpf)* Except blow-out fixtures: 3.5 (gpf) |
| Commercial urinals | 1.0 (gpf) |
| 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 |
| Commercial prerinse spray valves (for food service applications) |
Flow rate ≤ 1.6 (gpm) (no pressure specified; no performance requirement) |
| Residential Fixtures, Fittings, and Appliances | Current Baseline |
|---|---|
| Residential toilets | 1.6 (gpf)*** |
| Residential lavatory (bathroom) faucets | 2.2 (gpm) at 60 psi |
| Residential kitchen faucet | |
| Residential showerheads | 2.5 (gpm) at 80 (psi) per shower stall**** |
|
* EPAct 1992 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 (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. For each increment of 2,500 square inches 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. |
|
1 Tables adapted from information developed and summarized by the U.S. Environmental Protection Agency (EPA) Office of Water based on requirements of the Energy Policy Act (EPAct) of 1992 and subsequent rulings by the Department of Energy, requirements of the EPAct of 2005, and the plumbing code requirements as stated in the 2006 editions of the Uniform Plumbing Code or International Plumbing Code pertaining to fixture performance.
The following fixtures, fittings and appliances are outside the scope of the water use reduction calculation:
- Commercial Steam Cookers
- Commercial Dishwashers
- Automatic Commercial Ice Makers
- Commercial (family sized) Clothes Washers
- Residential Clothes Washers
- Standard and Compact Residential Dishwashers"
- LEED 2009 for Commercial Interiors Rating System, page 9-10
LEED-CI Version 2.0
"Based on tenant occupancy requirements, employ strategies that in aggregate use 20% less water than the water use baseline calculated for the tenant space (not including irrigation) after meeting Energy Policy Act of 1992 fixture performance requirements."
- LEED-CI Version 2.0 Reference Guide, page 104
LEED Submittals
LEED-CI Version 3
- "Determine the type and number of occupants
- Retain manufacturers' data showing the water consumption rates, manufacturer, and model of each fixture and fitting.
- List plumbing fixtures by usage group, if applicable.
- Define each usage group used."
- LEED-CI Version 3 Reference Guide, page 106
(Complete descriptions of documentation requirements are on LEED-Online)
LEED-CI Version 2.0
“Provide the LEED Letter Template, signed by the MEP engineer or responsible party, declaring that the project uses 20% less water than the baseline fixtures performance requirements of the Energy Policy Act of 1992.
“Provide the spreadsheet calculation demonstrating that water-consuming fixtures specified for the stated occupancy and use of the building reduce occupancy-based potable water consumption by 20% compared to baseline conditions."
- LEED-CI Version 2.0 Reference Guide, page 104
Additional Resources
WEc1: Water Use Reduction *
WEc1 ROADMAP
| Design Phase | Recommended Approach: Activities | Recommended Approach: Responsibilities |
|---|---|---|
| Pre-Design | Set the goal of at least a 40% potable water reduction. | Client |
| Conceptual Design | Review WEc3 requirements. Calculate baseline water use based on FTE count and EPAct of 1992 requirements. Calculate the design case with fixtures that exceed EPAct of 1992 requirements. | Engineers |
| Schematic through Construction Documents | Calculate design use for sewage conveyance. Include water-efficient plumbing fixture requirements in the project specifications. Specify dual-flush toilets, low-flow lavatories with automatic faucets, and waterless urinals. If applicable, specify water-efficient kitchen dishwashers or washing machines. Consider composting toilets. See the Technologies & Products section for products used at Harvard. | Engineers |
| Schematic Design | Consider using rainwater for flushing toilets. A dual-plumbing system is necessary for greywater reuse. Identify the amount of water that could be collected from interior greywater, or stormwater, for flushing toilets. | Architect/Engineers |
| Construction Documents | Complete LEED Online Letter Template and provide submittal requirements. | Engineers or OFS |
| Construction Documents to Construction | Ensure dual-flush toilets, low-flow lavatories with automatic faucets, and waterless urinals are specified. Ensure submittals are reviewed and approved per the specifications requirements. | Engineers |
| Construction Documents | This credit is a Design Submittal and should be submitted to the USGBC after construction documents are complete. | OFS or LEED Consultant |
| Construction | Review Contractor submittals to ensure water efficient fixtures are selected. | Engineers |
Design Intent and Sustainability Principles
Potable water is a limited natural resource, and increasing water efficiency in buildings conserves this resource and reduces the burden on municipal water supply and wastewater systems.
Financial Considerations
Water-saving fixtures, such as dual-flush toilets, waterless urinals, low-flow faucets and showerheads are comparable in price to standard fixtures, and have been used in numerous Harvard buildings. See the Technologies & Products section for more details.
LEED Requirements
See updated Credit Interpretation Rulings issued by the U.S. Green Building Council.
LEED-CI Version 3
"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:
Percentage Reduction |
Points |
|---|---|
30% |
2 |
35% |
3 |
40% |
4 |
Calculate the baseline according to the commercial and/or residential baselines outlined below.1 Calculations are based on estimated occupant usage and must include only the following fixtures and fixture fittings (as applicable to the project scope): water closets, urinals, lavatory faucets, showers, kitchen sink faucets and pre-rinse spray valves.
| Commercial Fixtures, Fittings, and Appliances | Current Baseline |
|---|---|
| Commercial toilets | 1.6 gallons per flush (gpf)* Except blow-out fixtures: 3.5 (gpf) |
| Commercial urinals | 1.0 (gpf) |
| 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 |
| Commercial prerinse spray valves (for food service applications) |
Flow rate ≤ 1.6 (gpm) (no pressure specified; no performance requirement) |
| Residential Fixtures, Fittings, and Appliances | Current Baseline |
|---|---|
| Residential toilets | 1.6 (gpf)*** |
| Residential lavatory (bathroom) faucets | 2.2 (gpm) at 60 psi |
| Residential kitchen faucet | |
| Residential showerheads | 2.5 (gpm) at 80 (psi) per shower stall**** |
|
* EPAct 1992 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 (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. For each increment of 2,500 square inches 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. |
|
1 Tables adapted from information developed and summarized by the U.S. Environmental Protection Agency (EPA) Office of Water based on requirements of the Energy Policy Act (EPAct) of 1992 and subsequent rulings by the Department of Energy, requirements of the EPAct of 2005, and the plumbing code requirements as stated in the 2006 editions of the Uniform Plumbing Code or International Plumbing Code pertaining to fixture performance."
The following fixtures, fittings and appliances are outside the scope of the water use reduction calculation:
- Commercial Steam Cookers
- Commercial Dishwashers
- Automatic Commercial Ice Makers
- Commercial (family sized) Clothes Washers
- Residential Clothes Washers
- Standard and Compact Residential Dishwashers
- LEED 2009 for Commercial Interiors Rating System, page 11-12
LEED-CI Version 2.0
"Based on tenant occupancy requirements, employ strategies that in aggregate use 20% less water than the water use baseline calculated for the tenant space (not including irrigation) after meeting Energy Policy Act of 1992 fixture performance requirements."
- LEED-CI Version 2.0 Reference Guide, page 104
LEED Submittals
LEED-CI Version 3
- "Determine the type and number of occupants
- Retain manufacturers' data showing the water consumption rates, manufacturer, and model of each fixture and fitting.
- List plumbing fixtures by usage group, if applicable.
- Define each usage group used."
- LEED-CI Version 3 Reference Guide, page 106
(Complete descriptions of documentation requirements are on LEED-Online)
LEED-CI Version 2.0
“Provide the LEED Letter Template, signed by the MEP engineer or responsible party, declaring that the project uses 20% less water than the baseline fixtures performance requirements of the Energy Policy Act of 1992.
“Provide the spreadsheet calculation demonstrating that water-consuming fixtures specified for the stated occupancy and use of the building reduce occupancy-based potable water consumption by 20% compared to baseline conditions."
- LEED-CI Version 2.0 Reference Guide, page 113
Additional Resources
Updated: Wednesday, August 5, 2009 5:21 PM
