(1-2 points)
Intent
To conserve water used for mechanical processes and cooling tower makeup while controlling microbes, corrosion, and scale in the condenser water system.
Requirements
Option 1. Cooling Tower Water Use (1-2 points except CS, 1-3 points CS)
For cooling towers and evaporative condensers, conduct a one-time potable water analysis, measuring at least the five control parameters listed in Table 1.
Table 1. Maximum concentrations for parameters in condenser water
Parameter | Maximum level |
---|---|
Ca (as CaCO3) | 1000 ppm |
Total alkalinity | 1000 ppm |
SiO2 | 100 ppm |
Cl- | 250 ppm |
Conductivity | 2000 µS/cm |
µS/cm = micro siemens per centimeter
Calculate the maximum number of cooling tower cycles by dividing the maximum allowed concentration level of each parameter by the actual concentration level of each parameter found in the potable makeup water analysis. Limit cooling tower cycles to avoid exceeding maximum values for any of these parameters.
Table 2. Points for cooling tower cycles
Cooling tower cycles | Points (all except CS) |
Points (CS) |
---|---|---|
Maximum number of cycles achieved without exceeding any filtration levels or affecting operation of condenser water system |
1 | 1 |
Meet the maximum calculated number of cycles to earn 1 OR Meet the maximum calculated number of cycles to earn 1 |
2 | 2 |
Meet the maximum calculated number of cycles to earn 1 OR Meet the maximum calculated number of cycles to earn 1 |
-- | 3 |
Projects whose cooling is provided by district cooling systems are eligible to achieve Option 1 if the district cooling system complies with the above requirements.
OR
Option 2. No Cooling Tower (2 points)
For projects without cooling towers or evaporative condensers, projects may earn full credit if all conditions are met:
- the baseline system designated for the building using ASHRAE 90.1-2016 Appendix G Table G3.1.1 includes a cooling tower (systems 7 & 8)
- the project design case does not include a cooling tower
- the design case mechanical system does not use the latent heat of the evaporative cooling of water.
- the project does not receive any cooling from a District cooling system
All other system types are ineligible for credit.
OR
Option 3. Process Water Use (1-2 points except CS, 1-3 points CS)
Demonstrate that the project is using minimum 20% recycled alternative water to meet process water demand for 1 point, or using minimum 30% recycled alternative water to meet process water demand for 2 points. Ensure that recycled alternative water is of sufficient quality for its intended end use.
Minimum percentage of recycled alternative water used should be based on water use during the month with the highest water demand.
Process water uses eligible for achievement of Option 3 must represent at least 10% of total building water use. Eligible subsystems may include:
- Boilers
- Humidification systems
- Other subsystems using process water
Projects whose cooling is provided by district cooling systems are eligible to achieve Option 3 if the district cooling system complies with minimum thresholds for recycled alternative water use.
CS projects:
Demonstrate that the project is using minimum 20% recycled alternative water to meet process water demand for 1 point, using minimum 30% recycled alternative water to meet process water demand for 2 points, or using minimum 40% recycled alternative water to meet process water demand for 3 points. Ensure that recycled alternative water is of sufficient quality for its intended end use.
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