Requirement Summary
This measure can be claimed if there is a black water recycling system that treats all the wastewater produced from all internal uses including from the toilets and kitchen. This recycled water must be reused on the project site. End uses may include flushing toilets, the HVAC system, cleaning the building, or irrigation of landscaping.
Intention
To reduce the use of water from the municipal supply and reduction of load on the local water and sewage infrastructure, a black water recycling system can be used.
Approach/Methodologies
When this measure is claimed, EDGE automatically calculates the potential supply of black water from the building and applies a reduction in municipal water demand across the end uses that can benefit from it. These include flushing toilets, cleaning of the building, the HVAC system, and irrigation of landscaping. The EDGE software assumes that most of the black wastewater from the building is collected, treated and stored properly to meet ongoing demand. If the quantity of treated black water is insufficient, then only a portion of the demand is shown to be met by the treated water.
A water balance model must be produced by the design team to demonstrate the potential for water recycling.
The recycled water must be reused for flushing toilets, with the remainder directed towards other uses. Where this water is not used for toilet flushing, the project must provide additional documentation that the system is indeed replacing municipal water supply. For example, if the recycled water is being used for irrigation only, then the project must demonstrate that (a) the landscaped area requires municipal water (in addition to just natural rainwater), and (b) the system is designed to serve the landscape, thus replacing water from the municipal supply. This can be done with drawings of the plumbing layout at the design stage, and with pictures that show the planned piping system connected to the irrigation system at the post-construction stage.
Grey water is included in black water, so there are no additional savings from a grey water system when a black water system is selected.
Potential Technologies/Strategies
Treated water must be in accordance with local or international health and sanitary code requirements (whichever is more stringent).
When recycling the water, a dual piping system must be used to separate the recycled water from the main.
In some cases, the black water treatment plant could be centralized for a combination of buildings within the development. In these cases, the central plant must fall within the site boundary of the project, or be managed by a company within the control of the site owner. This is to ensure continuity of sustainable management and future access to the system for maintenance.
If the black water treatment plant is located off-site, then a contract with the management company in charge of the water treatment must be provided as part of the documentation at the post-construction stage.
Some jurisdictions may not permit the use of recycled black water; in such cases this measure cannot be claimed.
Relationship to Other Measures
This measure affects the building energy use because the energy use of the water pumps required for the operation of the system is included in “Other” Energy use.
Assumptions
The base case assumes that there is no black water harvesting. The improved case assumes that all black water is re-used in the building for flushing water closets and urinals, landscaping, the HVAC system and cleaning (“Other”).
Compliance Guidance
| Design Stage | Post-Construction Stage |
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At the design stage, the following must be used to demonstrate compliance:
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At the post-construction stage, the following must be used to demonstrate compliance:
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