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Guideline S.8: Building Water Efficiency
Intent
To minimize municipal potable water or harvested groundwater (well water) use in buildings to conserve water resources and minimize water and wastewater treatment infrastructure impacts and cost.
Required Performance Criteria
- Reduce municipal potable water or harvested groundwater use in building by 30% compared to code (1992 Energy Policy Act requirements) for any fixture types referenced by those requirements. The criteria may be met by any combination of the following: selection of low or no flow fixtures, use of alternatively sourced water, or other strategies. Major Renovation projects may limit performance criteria application to the number of fixtures included in the renovation scope, however, even if no fixture replacement was planned in the renovations scope, for any plumbing fixtures within the renovated area: faucets in the renovated area must be upgraded with low-flow faucet aerators, and showerheads must be upgraded with low-flow showerheads. In order to verify compliance with this guideline during building operation, it is necessary to sub-meter indoor water consumption separately from irrigation.
Recommended Performance Criteria
- Reduce municipal potable water or harvested groundwater use in building by 50% compared to code (1992 Energy Policy Act requirements) for any fixture types referenced by those requirements. The criteria may be met by any combination of: selection of low or no flow fixtures, use of alternatively sourced water, or other strategies. Major Renovation projects may limit performance criteria application to the number of fixtures included in the renovation scope.
Use Worksheet S-8 Building Water Calculator to calculate building water use for base and design. This also shows EPA required flow and flush fixture rates, and example fixture performance values.
Implementation in the Design Process:
In Predesign and early design, develop a water efficiency improvement goal meeting or exceeding the guideline requirements.
Through the design process adapt the water efficiency goal, document it in the program, and communicate the water efficiency goal to all design team members. The water efficiency goal should also be documented in the specifications for the project.
Provide annual water use calculations showing the reduction in water use compared to code. Use the total daily water requirements from the Minnesota Plumbing Code and the Energy Policy Act as the basis of the calculations.
In the project’s construction documents confirm or revise calculations from the design development phase and specify compliant appropriate fixtures. Clearly indicate the water efficiency goal. Review submittals and verify compliance with specifications and confirm installation onsite.
Documentation
Documentation required for this guideline includes a completed Appendix S8 – Building Water Calculator. This evaluates the reduction from a base-case water scenario for regulated fixtures.
Design:
- S.8A: Base-case indoor water consumption.
Final Design:
- S.8A: Base and design case indoor water consumption, and alternatively sourced indoor water used, and completed Building Water Calculator documenting 30% reduction from base case.
- S.8B: Calculations from S.8A documenting 50% reduction from base case.
Closeout:
- S.8A: Updated base and design case indoor water consumption, and alternatively sourced indoor water used, updated completed Building Water Calculator documenting 30% reduction from base case, and verification that site contractor understands the requirements and intents of this guideline.
- S.8B: Calculations from S.8A documenting 50% reduction from base case.
Occupancy – Submitted annually for ten years:
- S.8A and S.8B: Indoor water consumption (collected through B3 Benchmarking) and verification that the building operator understands the intent of this guideline.