Inputs for Indoor Water Use are:
- Baseline Flow Rate: the assumed water consumption rate of code-compliant fixtures and fittings.
- Low Flow Rate: a reduced water consumption rate based on the selection of low-flow fixtures. Typically, a low-flow fixture will reduce water consumption by at least 20% when compared to conventional fixtures. The EPA WaterSense group has published a table (below, units in gal/flush) of Typical Flow Rates for each primary indoor water use fixture.
Indoor Water Use Fixtures: Permanently installed plumbing fixtures with running water.
- Toilets: a sanitary plumbing fixture used for human waster removal. Also known as a water closet.
- Urinals: a sanitary plumbing fixture for urination only.
- Showers: a plumbing fixture used for bathing.
- Kitchens: plumbing fixture used in common spaces. Includes kitchen sinks and drinking fountains. Exclude faucets used exclusively for filling operation, i.e. Janitorial faucets.
- Lavatories: plumbing fixture used in bathrooms. Also know as a washbowl or basin. Includes both public and private bathrooms.
- Greywater (%): untreated waste water which has not come into contact with toilet waste. Greywater is considered not suitable for human consumption, but can be treated and a substitute water source for laundry equipment, toilet flushing, and outdoor irrigation.
- Fixtures not included in the Indoor Water Use Tool:
- Clothes washers
- Dish Washers (standard or compact)
- Pre-rinse Spray Valves
- Ice Machines
- Utility sinks
Calculation Method and Results
The Indoor Water Use calculation method follows (BD+C) LEED v4.0 WE p2,c2 - Indoor Water Use Reduction credit, and AIA's COTE TopTen Toolkit: Measure 4 - Design for Water tool, section 1 - Indoor Water Use.
The four indoor water use related results are Indoor Reduction, Indoor LEED Points, Indoor WUI, Indoor Water Use by Building Type, and Indoor Water Use Breakdown bar graph. The difference between a baseline fixture flow rates and low flow rates determine indoor water use reduction. The LEED Rating systems for indoor water use reduction is on a 1 to 6 point scale and based on a %reduction threshold, table below.
WUI, or Water Use Intensity, is the amount of gallons by building area required used for daily operations. Water Use by Building type is the amount of water, measured in gallons per year, used for each building template. Mixed-use projects will have multiple buildings types inside a single project, so cove.tool will explain how much water is being used for each section. Last, cove.tool graphs annual indoor water use by fixture in the breakdown bar graph. This is calculated by occupant density to determine number of fixtures, days of operation by using user defined schedules, and user determined fixture flow rates. Note that Duration of Use and Uses per Day are taken from "LEED v4.0 - WE p2, Table 8 &9: Nonresidential and Residential default fixture uses" and default gender ratio is 50:50.
Q1. Can I use cove.tool's water tool for LEED points?
A1. Yes! It can be used for Integrative Process Credit and understanding how many anticipated points can be achieve by building design, but LEED requires a more detailed tracking tool for credit compliance. This water tool is for planning and concept testing. Our intention is to get this to compliance level in subsequent updates. Stay tuned!
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