Pilot-Credits PC17: Cooling Tower Water Use

  • Orginated in LEED-EBOM

    This is a modified version of the Cooling Tower credits originally in LEED for Existing Buildings: Operations & Maintenance.

    Credit Submittals

    General

    1. Register for Pilot Credit(s) here.
    2. Register a username at LEEDuser.com, and participate in online forum
    3. Submit feedback survey; supply PDF of your survey/confirmation of completion with credit documentation

    Credit Specific

    New Construction, Retail – NC, Schools, Core & Shell and Healthcare Projects:

    Provide the following:

    1. A water analysis measuring as a minimum the five control parameters measured in ppmParts per million. or mg/l.
    2. Verification that sidestream filtration will be provided
    3. Proof of a meter on both the make-up and discharge from the tower.
    4. Location of conductivity meterA device that measures the amount of nutrients and salt in water. Also know as a EC meter..
    5. Diagram showing meter locations, sand filter.
    6. Drift eliminators specified on the tower achieving efficiencies of 0.2% or greater for counter flow or 0.5% or greater for cross flow systems.
    7. Narrative describing the water treatment system and the number of cycles which the cooling tower can achieve without exceeding the control parameters.  The narrative should also include the predicted acceptable corrosion rates for each pipe material within the condenser water system.

    Existing Buildings: Operations & Maintenance Projects:

    Provide the following:

    1. A water analysis measuring as a minimum the five control parameters measured in ppm or mg/l.
    2. Narrative describing the water treatment system and the number of cycles which the cooling tower can achieve without exceeding the control parameters.  The narrative should also include the predicted acceptable corrosion rates for each pipe material within the condenser water system.

    Additional Questions

    None

  • USGBC

    Excerpted from LEED 2009 for New Construction and Major Renovations

    WE Pilot Credit 17: Cooling tower water use

    Intent

    To conserve water used for cooling tower makeup while controlling microbes, corrosion, and scale in the condenser water system.

    Pilot Credit Closed

    This pilot credit was closed to new pilot credit registrations on 3/1/2015. It is now available in the LEED Innovation Catalog for ongoing use by project teams as an innovation point rather than a pilot credit.

    Requirements

    * This credit language is drawn from the LEED v4 draft. Where other point totals are noted, this pilot credit is worth 1 point in total. *

    For cooling towers and evaporative condensers, conduct a one-time potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. analysis, in order to optimize cooling tower cycles. Measure 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 ppmParts per million.
    Total alkalinity 1000 ppm
    SiO2 100 ppm
    Cl- 250 ppm
    Conductivity 2000 µS/cm





    ppm = parts per million

    µS/cm = micro siemens per centimeter

    Calculate the 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. 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
    Maximum number of cycles achieved without exceeding any filtration levels or affecting operation of condenser water system (up to maximum of 10 cycles) 1
    Achieve a minimum 10 cycles by increasing the level of treatment in condenser or make-up water

    OR Achieve the number of cycles for 1 point and use a minimum 20% recycled nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents.
    2



    General Pilot Documentation Requirements

    Register for the pilot credit

    Credits 1-14

    Credits 15-27

    Credits 28-42

    Credits 43-56

    Credits 57-67

    Credits 68-82

    Credits 83-103

    Credit specific

    Provide the following:

    1. A water analysis measuring as a minimum the five control parameters measured in ppm or mg/l.
    2. Narrative describing the water treatment system and the number of cycles which the cooling tower can achieve without exceeding the control parameters. The narrative should also include the predicted acceptable corrosion rates for each pipe material within the condenser water system.
    Additional questions:

    none

    Changes
    • Changes made for 2nd Public Comment (08/01/2011):

      Separate language for EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. projects to conform with new EBOM rating system structure

      Added Healthcare as an applicable rating system type.

      Clarification of cooling tower analysis process which requires a one time potable water analysis, following by an assessment of the maximum number of cycles appropriate to the project, along with additional measures to improve cooling tower efficiency.


    • Changes made for 3rd Public Comment (03/01/2012):

      Removed CI & Retail CI from applicable rating systems

      Removed equipment requirements from EB:O&M

      Separated EBOM & BD+C submittal requirements to reflect change to EBOM requirements.


    • Changes made for 5th Public Comment (1/15/2013):

      Updated tables to align with 5th Public Comment changes to LEED v4 WEc3.

      Removed additional BD+C documentation requirements that correspond to WEp2 from v4 draft.



Organizations

LEED Pilot Credit Library

The homepage for the LEED Pilot Credit Library. The LEED Pilot Credit Library is intended to facilitate the introduction of new prerequisites and credits to LEED. This process will allow USGBC to test and refine credits through LEED 2009 project evaluations before they are sent through the balloting process for introduction into LEED.

Articles

Foundations of LEED

Background for the LEED Pilot Credit Library is provided in this foundational document.

30 Comments

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Christina Nybergh LEED AP BC+D Skanska Talonrakennus Oy
Oct 05 2016
LEEDuser Member
57 Thumbs Up

Experiences about ACP Pilot Credit – No Cooling Tower (WEpc94)?

Project Location: Finland

Hi,
anyone got any experience with the Alternative Compliance Path WEpc94 – No Cooling Tower? http://www.usgbc.org/node/5586086?return=/pilotcredits/all/v4
(This pilot credit is an alternative compliance path to the LEED v4 credit Cooling tower water use for the maximum number of points under each credit)

The requirement:
Projects may earn full credit if all conditions are met:
• the baseline system designated for the building using ASHRAE 90.1-2010 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

Credit Specific Documentation
Provide documentation showing that the project meets all requirements including:
• Documentation showing that the project is designated as systems 7 or 8 under ASHRAE 90.1-2010 Appendix G Table G3.1.1
• Documentation (site plan or mechanical system plan, energy model or other) showing that the project design case does not include a cooling tower or other system that uses the latent heat of the evaporative cooling of water, and is not connected to a District cooling system..
Documentation should be uploaded under the Cooling Tower Water Use credit form in LEED Online.

We documented according to all of the requirements above but the inspection team still denied this credits with the following comment:

The LEED Form states that the project does not have cooling towers. However, not all credits are applicable to all
projects. A pilot alternative compliance path may be available for this credit to certain project types without cooling towers. For more information, please visit the Pilot Credit Library.

Any ideas of why the credit was denied when we documented according to requirements?

Best,
Christina

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Izabela Kwiecinska Gleeds Polska Apr 07 2017 LEEDuser Member 13 Thumbs Up

Hi Christina,
It's been a while since your comment. Do you have more clarification why the ACP was denied?
I am working on the same credit and don't know if it's worth to try...
Best,

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Janice Rogers Design Manager/LEED Manager Kirlin Builders
Jun 30 2016
Guest
35 Thumbs Up

Never Have Cooling Towers

Project Location: United States

We do small renovations and have never installed or replaced a cooling tower. Do I still have a "no" credit even if I can't meet the criteria of the credit because we don't have the equipment? Seems unfair.

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Phuc Do Senior Electrical Engineer Aurecon
Mar 11 2015
Guest
15 Thumbs Up

Cooling tower cycles

Project Location: Australia

Hi all,

Our project is using Munters cooling tower in which the cooling tower cycles measured continuously and the dump cycle adjusted accordingly. Therefore, the requirement for measuring the water quality is not necessary (its continuously measured).

Does anyone have experience with this system and know if this is acceptable to GBCIThe Green Building Certification Institute (GBCI) manages Leadership in Energy and Environmental Design (LEED) building certification and professional accreditation processes. It was established in 2008 with support from the U.S. Green Building Council (USGBC). or not?

Thanks.

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Kath Williams LEED Fellow 2011, Principal Kath Williams + Associates
Sep 12 2013
LEEDuser Member
2374 Thumbs Up

Basic learning...

For a "non-engineer," could someone please explain what I'm hearing on the project testing this pilot credit--operator concern that cooling tower won't perform as designed and water-testing analysts advice NOT to operate at levels recommended in this pilot credit? Again, I need the basics and the questions to ask????

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Kath Williams LEED Fellow 2011, Principal, Kath Williams + Associates Oct 31 2013 LEEDuser Member 2374 Thumbs Up

This pilot credit was denied based on the submitted documentation. For purposes of education, here are the final review comments.

"A revised LEED Credit Form has been provided stating that the project has registered for Pilot Credit 17: Cooling Tower Makeup Water. A one-time potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. analysis has been conducted measuring the five control parameters in ppmParts per million. or mg/l (calcium (Ca); total alkalinity; silica (Si);
chloride (CI); and conductivity). The cooling tower cycles have been calculated and limited to avoid exceeding maximum values the credit parameters. The system and metering credit criteria have also been incorporated. The following documentation has been provided: 1) a water analysis measuring the five control parameters (measured in ppm or mg/l); 2) confirmation of the location of the
conductivity meterA device that measures the amount of nutrients and salt in water. Also know as a EC meter.; 3) the diagram showing meter locations; and 4) a narrative describing the water treatment system and the number of cycles which the cooling tower can achieve without exceeding the control parameters. Additionally, a project team representative has registered with LEEDuser, and the feedback survey has been completed. A copy of the Cooling Tower Water Use found on USGBC
website has also been provided.
However, the provided narrative does not include information regarding the predicted acceptable corrosion rates for each pipe material within the condenser water system. The documentation does not demonstrate credit compliance."

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Kenner Kingston Director of Sustainability Architectural Nexus
May 16 2013
LEEDuser Member
67 Thumbs Up

Sand Filter

The credit requirement #5 asks for a "diagram showing meter locations, sand filter.:
Is a sand filter required to meet the credit?

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USGBC IP Account U.S. Green Building Council May 16 2013 LEEDuser Member 598 Thumbs Up

A sand filter is not required - here is the newest version of the pilot credit - http://www.usgbc.org/node/2606869?return=/pilotcredits if you registered for the credit befor 1/15/2013 and would prefer to use the older version of the credit, you can just document that there is a side stream filtration system.

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Charles Chaloeicheep Built Ecology / WSP Group
May 14 2013
Guest
45 Thumbs Up

Pipe Corrosion Rates

How do you determine the predicted acceptable corrosion rates for each pipe material in the condenser water system?

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Sara Greenwood Green Building Consultant Cadmus Group
Apr 15 2013
LEEDuser Member
236 Thumbs Up

Providing verification that there will be side stream filtration

Our project is pursuing an ID point for Pilot Credit 17 under the LEED-NCv2009 rating system. In reviewing the requirements, we had submitted an inquiry regarding "verification that there will be side stream filtration" and whether a cutsheet would suffice and if a sand filter is required as part of the side stream filtration system?

GBCIThe Green Building Certification Institute (GBCI) manages Leadership in Energy and Environmental Design (LEED) building certification and professional accreditation processes. It was established in 2008 with support from the U.S. Green Building Council (USGBC). did respond to our inquiry and stated: "1. A cut sheet is a sufficient submittal to verify that side stream filtration is provided in the project.
2. No, a sand filter is not required to be part of the side stream filtration system."

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Edward Malesevich Sustainability Advisor Transwestern Sustainability Services
Mar 13 2013
LEEDuser Expert
390 Thumbs Up

One-Time Potable Water Analysis

When the credit requirements ask for a "one-time" potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. analysis to be conducted, what sort of time-frame is required for this to be completed? If I'm working on an EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. project, does the analysis have to be completed during the performance period? The credit doesn't necessarily state when the analysis has to be completed, or how long the results are valid until another test would have to completed.

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USGBC IP Account U.S. Green Building Council Mar 13 2013 LEEDuser Member 598 Thumbs Up

Edward - For EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating systems. projects, the potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. analysis should be done within the last 5 years (5 years of submitting for certification) - the goal is to get an idea of what type of water the cooling tower is using in terms of dissolved solids, and how that water and system can be optimized, so the analysis doesn't need to be done very frequently in order to get to the result. Here's the EBOM pilot credit language, which mirrors the v4 draft proposal.

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April Eisenhauer Mechanical Engineer ccrd
Jan 31 2013
Guest
108 Thumbs Up

LEED HC WEc4.2 vs Pilot Credit 17

A long-term healthcare project I have been working on that was registered under LEEDv2.2 recently got resistance for submitting LEED HC WEc4.2 as an ID credit. Our review came back requiring us to switch to Pilot Credit 17. At this point it is not a big deal since we comply with all of the requirements and it is just the paperwork required to provide the clarification, but can anyone confirm why we got the resistance in the first place and why our original submission was not acceptable? It sounds like everything about the submission was correct; they just wanted us to revise it to Pilot Credit 17. How are project teams supposed to know if a Pilot Credit is more appropriate than a credit from a different rating system?

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Tristan Roberts LEED AP BD+C, Executive Editor – LEEDuser, BuildingGreen, Inc. Jan 31 2013 LEEDuser Moderator

April, I don't know what kind of "resistance" you got, but here's my best guess: the PC17 language is more up-to-date with where USGBC sees a cooling tower water credit going—the PC17 language is more recent than HC WEc4.2. So perhaps someone thought that as long as you were doing an innovation credit, they might as well have you use this new language that's being piloted, and thus it's a win for the project and a win for LEED development rather than just the former. The requirements are also intended more broadly for BD&C, and not just HC.

This is pure conjecture, mind you, but I think it's plausible.

As a general rule, I would advise teams to consider the Pilot Credit Library as a first place to go when considering innovation credits, because of the feedback that it provides to the LEED development process.

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April Eisenhauer Mechanical Engineer, ccrd Feb 01 2013 Guest 108 Thumbs Up

Makes sense. Really the only resistance we got was that the credit was bounced back during review so we had to provide some additional documentation. I think it will be accepted this go-around.
Thanks for your thoughts! I think I will look through the Pilot Credit Library for my next project.

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Susan Walter Specifications Director, Populous Feb 01 2013 LEEDuser Expert 22869 Thumbs Up

I wonder if it also has something to do with the nature of your project. Is is all new construction or renovation? My other thought was the difference between a v2.2 project and v3. The GBCIThe Green Building Certification Institute (GBCI) manages Leadership in Energy and Environmental Design (LEED) building certification and professional accreditation processes. It was established in 2008 with support from the U.S. Green Building Council (USGBC). often sees renovation projects in hospitals as more aligned with CI or CS than HC as well.

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April Eisenhauer Mechanical Engineer, ccrd Feb 04 2013 Guest 108 Thumbs Up

Susan, our project is new construction - healthcare facility. I had heard that you could submit credits approved in newer versions of LEED as ID credits which is why we pursued that one from LEED HC. I was just surprised that we had to re-issue it as a Pilot Credit instead. Again, it wasn't really a big deal since we met all of the requirements either way.
Good thought, though. Some rating systems align better than others.

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Jonathan Weiss
Sep 07 2012
LEEDuser Member
2636 Thumbs Up

Sidestream filter?

The credit requirements do not call for a sidestream filter, but the documentation requirements list that we should confirm that a sidestream filter is being provided. Why is that?

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Batya Metalitz Technical Director, LEED, USGBC Sep 10 2012 LEEDuser Expert 4055 Thumbs Up

You're correct that the credit requirements do not call for a sidstream filter. They are filtration systems alongside the cooling tower that filter a small percentage of the water at a time. They are fairly common on high performance cooling towers, but are not a requirement. Instead, please describe the filtration system utilized or provide a narrative explaining why this system does not include filtration. We're mainly looking to see the process by which the system is protected from corrosion and build-up.

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WAGNER OLIVEIRA SILVA CTE
May 22 2012
Guest
711 Thumbs Up

One-time potable water analysis

In the new version of Pilot credit Revised at 1/3/2012 they ask to be done one-time potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. analysis. How do we do if our project already covers 100% makeup water with non-potable water?

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Batya Metalitz Technical Director, LEED, USGBC Sep 04 2012 LEEDuser Expert 4055 Thumbs Up

Hi Wagner, that's a good question. If the project isn't using any potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. for cooling tower makeup, then I think the most appropriate thing would be to do an analysis of your non-potable water source for the same purpose - to show that it can be cycled through multiple times without creating build up or performance problems.

Would that work in your case?

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WAGNER OLIVEIRA SILVA CTE Sep 10 2012 Guest 711 Thumbs Up

Hi Batya, first of all thanks for your reply.

This does not work in our case, since the non-potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. will be generated only when the building comes into operation.

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Batya Metalitz Technical Director, LEED, USGBC Sep 10 2012 LEEDuser Expert 4055 Thumbs Up

Hi Wagner, that would make the credit harder to achieve, but assuming that non-potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. is the only source you're planning to use on the cooling tower, I would assume there is some planning or calculation going into the setup. In that case, the documentation could show 1) how much non-potable water you expect to generate for cooling tower use (and what type, it would need to have low dissolved solids) 2) how you plan to deliver it to the system and 3) how you will meet the dissolved solids and cycles of concentrationConcentration ratio is the ratio of the level of dissolved solids in the recirculating water to the level found in the entering makeup water. A higher concentration ratio results from a lower bleed-off rate; increasing the ratio above a certain point, however, leads to scaling, and water savings diminish after a certain level. This ratio is also called the cycles of concentration. Cycles refers to the number of times dissolved minerals in the water are concentrated compared with makeup water, not to water flow over the tower or to on-off cycles. as outlined in the credit - perhaps filtration/treatment, or perhaps the source is very pure to begin with.

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Dana Murdoch
Jul 14 2011
Guest
1051 Thumbs Up

2009 for Schools

Can this PC17 be used for LEED 2009 for Schools??

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Tristan Roberts LEED AP BD+C, Executive Editor – LEEDuser, BuildingGreen, Inc. Jul 14 2011 LEEDuser Moderator

Yes, according to the main pilot credit guide from USGBC, LEED for Schools can use PC17.

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Jie Zhang
Apr 01 2011
Guest
112 Thumbs Up

questions of Install Drift Eliminators and minimum efficiencies

In the pdf download from usgbc.org, one of the credits requirements is 'install drift eliminators that achieve minimum efficiencies of 0.2% for counter-flow systems or 0.5% for cross-flow system'.
Anyone who knows this efficiencies? What doest it mean? And how to calculate or measure?
Thanks very much.

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Jie Zhang Apr 19 2011 Guest 112 Thumbs Up

Compared the LEED requirement of drift eliminator the minimum efficiencies are more higher than Chinese standard requirements.
Now what I want to know is how about the average level of drift eliminator in USA.
Another question is about the maximum level of conductivity. The unit of conductivity is μS/ml, however I do some study of this value that the unit is μS/cm. I wonder that it is just a printing mistake or the 'μS/ml' needs to convert to 'μS/cm'.
Thanks and hope for answer.

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Batya Metalitz Technical Director, LEED, USGBC May 25 2011 LEEDuser Expert 4055 Thumbs Up

The credit authors have looked over this credit and believe that the units for conductivity are correct with μS/ml, with ml being equal to cm3. They are also staying with the drift eliminator values listed in the credit. This credit is currently being revised though, and we'll have a new version out in July that may help to clarify.

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William Wong
Jan 26 2011
Guest
879 Thumbs Up

How long does the monthly monitoring last for?

One of the mentioned requirements is to report results of the amount of potable waterWater that meets or exceeds U.S. Environmental Protection Agency drinking water quality standards (or a local equivalent outside the U.S.) and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. used, microbiological levels, blowdownAlso referred to as bleed-off; the removal of makeup water from a cooling tower or evaporative condenser recirculation system to reduce concentrations of dissolved solids that can cause mineral buildup. and corrosion on monthly basis, but for how long after occupancy?

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Chrissy Macken Assistant Project Manager, LEED v4 , U.S. Green Building Council Feb 08 2011 LEEDuser Member 1954 Thumbs Up

Hi William -

Staff is going to check in with the Water Efficiency TAGLEED Technical Advisory Group (TAG): Subcommittees that consist of industry experts who assist in developing credit interpretations and technical improvements to the LEED system. on this one. For now, show that you have performed the test for a three month period. If you are an NC project, show a contract or some other intent to have ongoing monthly reports.

Does this make sense?

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