EBOM 2009 WEc4: Cooling Tower Water Management

HI Jiri,

Unfortunately, it seems that way. If the project does not have cooling towers, then I believe that WEc4 cannot be pursued.

Hi Anshul,

I believe that all cooling towers in the building should be included for WEc4, including mechanical services cooling towers.

Hi Micheal,

There is a related credit in the LEED Pilot Credit Library that can be pursued as one of your ID points for a New Construction project. Its called PC 17: WE - Cooling Tower Makeup Water.

Find PC17 and info on how to use the Pilot Credits here:
http://www.usgbc.org/DisplayPage.aspx?CMSPageID=2104

From my experience, that should be fine. Anybody else have thoughts?

Hi David,

In this situation I would provide information on the training available to whoever it is on your team who contracts with and oversees the work done by the outside maintenance contractor.

Another idea would be to ask what training the vendor provides to its clients. Often, the person maintaining the chemical treatmentChemical treatment includes the use of biocidal, conditioning, dispersant, and scale-inhibiting chemicals to control biological growth, scale, and corrosion in cooling towers. Alternatives to conventional chemical treatment include ozonation, ionization, and exposure to ultraviolet light. will work with the client to understand what they are to do between their visits and when to call if there is a problem, etc. I think that is "training" but not as formal.

My guess is USGBC is interested in the long term performance of the treatment system, to make sure it is performing at the level intended.

To document training for a building with partially outsourced maintenance, we submitted training certificates from the specialist to the on-site engineers noting dates within the performance period. However, the credit is pending, "more details on the duration, frequency, and subjects of staff training as it relates to cooling tower maintenance."
Be sure you include all those variables in your written plan.

Anderson, first I would note that it's the WEc4.2 form that you're referring to.

Second, I think the issue you're having is the "Meter Coverage(% of Total
Cooling Towers)" entry. I put in 100% for both numbers, potable and nonpotable, and got the correct output. Perhaps you have different numbers entered there.

Jean, that's a complex question. I would say it has a lot to do with the building, its size and heating/cooling loads, efficiency of relevant equipment, etc.

If you don't have a cooling tower you're not eligible for these two points, but I wouldn't let that influence design and operation decisions.

This is a massive generalization, but when chillers are the selected system, smaller chillers will be better air cooled, and larger chillers better water cooled. There are all sorts of other factors like load profile, because air cooled (which are often screw or scroll compressors) have very good part load performance, where centrifugal chillers tend to have better full load performance for base loading.

So,it really all depends on the project, and should be examined carefully during the energy modeling early in the project. There are other options when you have a water cooled system such as heat recovery chillers and water-side economizerAn economizer is a device used to make building systems more energy efficient. Examples include HVAC enthalpy controls, which are based on humidity and temperature. too.

I know what you're saying...I've read loads of articles in ASHRAE journal, basically all saying that the efficiencies of Chilling Equipment should really be modelled and not read out of the back of ASHRAE 90.1, exactly because, as you say, the environmental loads, outdoor humidity, size, part loading and many other factors hugely impact on it's efficiency.

I've also read articles testing air cooled and water cooled solutions on specific and divers problems trying to extrapolate trends...basically saying that "well, it depends".

That's why I first felt like this existing building was unduelly penalized for having air cooled chillers.

I'm not going to try and fuddle in a cooling tower where it doesn't fit, don't worry. I just know that there is usually reason behind these things from the USGBC. It could be as simple as that the majority of chillers in the USA are water cooled and this water (probably potable) is being thrown away. I remember how shocked I was to here how late the USA was at bringing in laws forbidding (controlling) the use of potable ground water for cooling in power plants (mostly also cooling towers). It was like 40% of potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. was used in cooling towers in power plants, even right next to the see. Water is obviously way to cheep.

Thanks for the input.

Yes, we just did a large rainwater capture project, and in preparing for a presentation, I learned that one of the major users of fresh water (not always treated, but definately non-salt) was power plants, and many were once-through!

In general, if the chiller is in good shape, it would be rare that switching a water cooled unit for the air cooled unit would pay back economically...there are many more energy efficiency measures that should be tried first.

I do think water is too cheap, and it does not take into account the social and infrastructure cost to a city, such as urban areas with combined storm and sewer systems. But that is a different thread. One thing we seem to include in more projects is rainwater capture for cooling tower makeup, which can help reduce chemical treatmentChemical treatment includes the use of biocidal, conditioning, dispersant, and scale-inhibiting chemicals to control biological growth, scale, and corrosion in cooling towers. Alternatives to conventional chemical treatment include ozonation, ionization, and exposure to ultraviolet light. costs. So, sometimes it is good to look at smaller systems even if you cannot support a large system for flushing.

Scott, you may be aware of this, but the DES guide for EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. came out about two weeks ago and is on the USGBC site. I would check that for the guidance you need.

Tristan;

I did see that, and opened it with great excitment, but alas, it only covers EA credits! So this is still an open question. However, as you read that document, I have to believe that applying credits to a DES where appropriate, with documentation of course, should be accepted.

Tristan and Scott,
I tried to answer the answer myself with your comments above BUT.... if we currently utilize our local utilities' DES for purchased chilled water, can we pursue this credit by working with the utility on their chemical management?

At this point we just do not know. The project we have that may pursue this is very long term and no decision has been made, so we may not know for a while.

My opinion, and it is only that, is if your provider can provide documentation that the comply with credit, then that should pass through to anyone that uses that service.

Hopefuly USGBC will clarify at some point, or someone will try it and report it here!

S, this is fairly uncharted territory. USGBC hasn't offered guidelines on what they're looking for. I am, however, looking for a sample and will post it here if I get it.

Oh well thank you Mr.Tristan!

Ashley, thanks for joining the forum. However, we're generally not wild about people posting here promoting their own services without at least adding some value in terms of tips on earning the credit, lessons learned, probing questions, or sample documentation.

We're also not big fans of general statements about how many credits a technology can get that aren't backed up with specifics. Many such claims are very overblown (no pun intended... you know cooling towers... :).

Care to add some real value here in terms of any of the above?

Thanks Tristan, I appreciate your feedback. I am new to the LEEDuser and noticed someone else was interested in this technology from a previous discussion.

I wasn't looking to promote as much as try to get some feedback on this technology and others like it for sustainable solutions to water conservation.

Cool,  it's good to have you here.

Any hot tips on using this technology to earn WEc4?

I would be interested to hear whether this technology has been submitted for EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. WEc4. It sounds like the same system we are submitting for an ID point under NC 2.2, referencing the CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide/Interpretation originally submitted for a different non-chemical treatmentChemical treatment includes the use of biocidal, conditioning, dispersant, and scale-inhibiting chemicals to control biological growth, scale, and corrosion in cooling towers. Alternatives to conventional chemical treatment include ozonation, ionization, and exposure to ultraviolet light. system.

The system we are using is a proprietary technology which one case-study article called 'zero liquid discharge'. It eliminates chemical corrosion, scale and biocide treatments, and eliminates regular blow-down. It's an intriguing system, and I'm looking forward to seeing how it performs on our project.

From what I've learned about the system so far, using it for WEc4.1 shouldn't be problematic, though it would require a 'special circumstances' narrative, since this system eliminates the need for some of the requirements of the credit.

However, I don't see how the technology, in and of itself, would have any bearing on WEc4.2 (per the other thread), since the elimination of water used for blow-down is still only a minor portion of the total water used by an evaporative cooling tower, whereas WEc4.2 requires at least 50% of makeup water to be from nonpotable sources.

From what you are describing, you are using a very innovative system that would in fact qualify for credit WEc4.1. If any of your makeup water is from a non-potable source you may also be able to qualify for 4.2 and possibly 4.3 as well. It would be great for LEED Users if you could share the system name. Good job!

You do understand things correctly, and raise a good question. It's kind of like EQc4.3 in earlier versions of LEED-NC, where you could only earn the point if you used carpet, so in some cases teams were adding small areas of carpet just to earn the point. Not exactly productive.

In that case, the credit was changed through a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide and in LEED 2009. LEED-EBOMEBOM is an acronym for Existing Buildings: Operations & Maintenance, one of the LEED 2009 rating sytems. definitely has some kinks; maybe this issue will be revisited in 2012.

Another note on this...you can only earn the irrigation credits if you actually have some amount of vegetation on your site (something to irrigate). An absence of vegetation itself results in the same situation as with the cooling towers - the points are off the table.