Credits WE 3.1 & WE 3.2 are the same except for the percent (%) reduction. If one completes the requirements and implementation for WE 3.2 – Water Use Reduction – 30%, they would also receive a point for WE 3.1. Thus, earning two points toward LEED accreditation for the project. The posts for WE 3.1 and WE 3.2 are exactly the same except for the percent reduction.
Water Use Reduction – 20%
Intention:
- Maximize water efficiency
- Reduce burden on municipal water supply
- Reduce burden on wastewater system
Implementation:
- Method: Use special fixtures and sensor/metering controls.
- ( fixture/flowrate in Gallons Per Minute [GPM] )
- Shower/2.5 (lowflow/1.8)
- Lavatory/2.5 (lowflow/1.8) (ultra lowflow/0.5)
- Kitchen Sink/2.5 (lowflow/1.8)
- Faucets/2.5
- Aerator/2.5
- Water Closet/1.6 (lowflow/1.1)
- Dual Flush Water Closet/1.6 (lowflow/0.8)
- Composting Toilet/0.0
- Urinal/1 (lowflow/0.5)
- Non-Water Urinal/0.0
- For calculations, consider:
- DO NOT include irrigation water
- Only applicable for the following fixtures:
-
- water closets
- urinals
- lavatory faucets
- showers
- kitchen sinks
- Daily Residential Usages:
- 1 person 5 uses per day of flush and flow fixtures
- Also use high-efficiency fixtures above, dry fixtures, occupant sensors.
- Consider reusing stormwater and graywater for non-potable uses.
Codes/Standards Applied:
- Energy Policy Act 1992 (different from the EPA)
Extra Credit:
- For both WE3.1 & WE3.2: 40% (instead of 20% or 30%) reduction of water usage
OR
- Process and non-regulated water use savings is at least 10%
Submittal Phase:
- design
Links from Reference Guide:
- Composting Toilet Reviews
- Terry Love’s Consumer Toilet Reports
- Water Efficiency Manual for Commercial, Industrial, and Institutional Facilities
- Water Measurement Manual: A Water Resources Technical Publication
- Water Wiser: The Water Efficiency Clearinghouse
Other Water Efficiency Credits
41 Comments On This Post
I think exemplary performance for these credits is 40% reduction, not 100%. My first edition of the NC 2.2 reference guide has no reference to the 10% process and non-regulated water use savings. Sorry if I’m clogging your blog!
Haha it’s ok. Someone made the same comment on 3.2, but I forgot to change 3.1 (from 100% to 40%). The 10% savings, however, IS in the second edition. I doubt it will be on the test though, but now you know. Thanks for backchecking my website for me, haha!
Keep em coming!
Hi Pat,
In WEc3.1 you have
For calculations, consider:
* Male to Female water usage ratio: 1 to 1
1. male:
o water closet = 1
o urinal = 2
2. female:
o water closet = 3
o use per day
and WEc3.2 you have Daily Residential Usages:
* 1 person 5 uses per day of flush and flow fixtures
Hi Pat,
I just think it is important to clarify that the 1:1 ratio of male and female user is in the commercial/institutional projects only. My impression is that when calculating FTE, the ratio of man and woman is assumed as 1:1. It is easy to take the 5 flush per day calculation for every situation while it is only good for residential projects.
I realize this is a pretty basic questions, but how do you calculate FTE’s??? Do you use occupancy requirements from the building codes?
thanks….Jeff
FTE is based on an eight hour workday. So, if you have 10 employees that work 2 hours a day, you would multiply 10 x 2 and divide that by 8 for a typical 8 hour workday
Margie,
How is the number of employees determined? Is it as simple as asking the owner how many employees will occupy the space? Or do you have to use the occupancy numbers from the code?
thanks…..Jeff
For residential WEC2 states that the number of residents is used as the occupancy number. I’m guessing that for commercial it’s based on actually asking the owner for occupancy numbers. Is doesn’s say anything about code.
i just found an example problem for WEC@. It uses a two-story office building with a capacity of 300 occupants. so i guess for commercial projects its based on building capacity.
What is the difference between WE 2 and CE3? They seem very similar by using high efficencey fixtures? Please explain.
Mark:
As I understand it, WE2 reduces the use of water used for waste-water purposes. WE3 reduces the _overall_ use of water which can be viewed as a more general/encompassing credit.
There is a lot of overlap but hopefully that just makes it easier to qualify for both credits.
Pat,
I have had this question twice now and I still can not figure out the answer. It states there is a women’s restroom in a commercial building with dual-flush water closets and either ultra or low flow lavatories and requests you to calculate the fixture count for the day. The answers consist of # of regular flush water closets, # of dual-flush water closets and # of lavatories. I can’t find any information in the study guide to provide the answer. I assume it is a trick question like most of them are. Let me know if you have any insite.
Thanks,
i’m not entirely understanding your question, but basically you assume 3 uses a day for m/f. 2 for urinal, 1 w/c. my guess for dual-flush would be one use and 2 for standard.
A project for a new library has achieved a 25 % reduction in water use. How many points will the project earn for achieving these goals.
A.0 B. 1 C.2 D.3
i picked B since a 20% reduction can earn WE credit 3.1(1pt)
However, the answer is A (according to green building education service)
It’s explanation was
A 20% reduction can earn WE Credit 3.1 (1pt). This project has achieved a 25% reduction.
A 30% reduction would have earned WE Credit 3.2 (2 pt)
So does that mean reduction percentage from 21 to 29 has zero points??
This doesn’t make any sense to me. Which answer is correct? Help ! thx.
cornell,
where did u get this question from…is this the entire question???
can u send me the link.i will show this to an expert.
Thanks
Pat,
I have a confusion on this 10% saving for ID credit, this 10% is calculated on total process water requirement as per some baseline data or any other figure.
Kindly clarify.
Dipankar
Is the baseline case supposed to be defined by the Energy Policy Act of 1992, or are the guidelines provided in EPAct the ones that are used to achieve the credit?
Ok. My question has to do with the Template. It doesnt give you a place to specify how MANY flush or flow fixtures… so here’s my question. is the calculation based solely on FTE? so if all 10 employees were using one WC or two it would not matter?? Since it is looking at water usage it should be the same wheter it was one restroom or two right???
21. You are required to provide what data for compliance with WE Credit 3, Water Use
Reduction? (Choose three)
A) ___ Dishwasher flow rates
B) ___ Number of fixtures
C) ___ Lavatory flow rates
D) ___ Fixture model and manufacturer
E) ___ Default baseline reduction of 20%
F) ___ Male-to-female ratio, in special occupancy situations
answer cdf i get c, but why d and f? are those the right answers?
Can someone answer this?
If you are able to get a point for WEc2, dont’ you then automatically qualify for 2 points for WEc3?
akoak,
No, because i believe WE2 reduces the use of water used for waste-water purposes. WE3 reduces the overall use of water.
By trying to get we2 you can achieve to get we3 easier… i guess
asma,
Dishwashers are not regulated by EPAct, so do not qualify for WE3.
Number of fixtures does not determine water use, the occupancy and therefore the number of uses per fixture type does.
Lavatory fixtures are regulated by EPAct, so does qualify for WE3.
Fixture model and manufacturer is data LEED requires with each fixture type (verification of specified flow rate?).
Question applies to WE3.1 and WE3.2, 20% applies only to WE3.1.
M/F ratio of 1:1 is assumed (in all credits I believe), but you are able to specify ratio in special cases.
Those tricksters. I imagine I will still get this question wrong when I take the test.
If 40% reduction of water usage (qualified for EP) is achieved, how many points (3 or 4 points) will be earned for WE 3 Water Use Reduction?
WE 3.1: 1 point earned for sure.
WE 3.2: 1 point earned for sure.
Exemplary Performance:
1 point for WE 3?
OR
1 point for WE 3.1 and another 1 point for WE 3.2?
Could anyone please let me know? Thanks.
Richard: you can only get 1 ID credit for exemplary performance in WE3, same as SS4, even though it is mentioned under each individual credit. Also, it sounds like you are making the same mistake I was awhile back. Achieving 40% here does not automatically give you a bonus point. You have to apply the WE3 bonus credit to one of 4 max ID1 credits. Sorry, if you already knew that…just making sure.
Wes,
Since you mentioned EP for SS 4. I have a question.
For SS 4.1 – 4.4, an extra ID point can be earned by creating a comprehensive transportation management plan. For SS 4.1 only, there is another way to earn ID point by doubling the threshold of the base credit. (Reference Guide page 51).
Can I earn an ID point with the transportation plan from SS 4.2 – SS 4.4, AND an ID point with doubling the threshold from SS 4.1?
Thanks.
No because only one ID credit is earned for each MAIN credit…. that means if 4.1 has achieved requirments for EP and so has 4.2- 4.4 you will only recieve one ID point for SSc 4
this section of LEED came up a lot for me in the exam.
(What’s the difference between flow volume and flow rate?)
😛
I think, as others have said, that given the amount of calculations that a typical LEED AP would do on a project for Water Efficiency credits, the exam spends some time on this area to make sure your knowledge is deep.
I just failed the exam getting a 167 out of 170. I had no real interest in getting accredited as it is not necessary for getting a project credited. Now I have to wait 7 days to reschedule a test that I thought was ridulously worded and intentionally tricky. Would someone please explain the benefits of being a LEED AP so that I might take this test. 1 point for being part of a project??
I need help with this qn.
An apartment complex is being renovated and turned into condominiums. The project team is considering reusing some of the water fixtures. To earn WE Credit 3 Water Use Reduction the existing showerheads would need a gpm rate of ____ and the water closets would need a gpf rate of _____
A 1.6, 1.6
B 1.6, 1.0
C 2.0, 1.28
D 2.5, 1.0
E 2.5, 1.6 (Answer, But WHY??)
Notes:
The fixtures for the project are required to meet the EPA Act of 1992. Then, the project must use 20% less water than the baseline calculated water use for the building. Each fixture does not have to use 20% less water to earn the credit. The aggregate use must be 20% or less (at a minimum for WE Credit 3.1).
Reenu.
This is from implementation; above.
I guess we need to memorise all mentioned fixtures above…
Implementation:
Method: Use special fixtures and sensor/metering controls.
( fixture/flowrate in Gallons Per Minute [GPM] )
Shower/2.5 (lowflow/1.8)
Water Closet/1.6 (lowflow/1.1)
Seems trivial, but I couldn’t give a clear answer to myself: What is the difference between WEc2 and WEc3.x – both are about reducing potable water use for sewage conveyance…
Can anyone tell me in essence what is the difference?
Thanks,
-Nadav
How can i get the results for the LEED 2.2 test?
In response to Pat on 8/19/08
Dual-Flush Water Closets and LEED Credits:
When dual-flush water closets are installed in the women’s rest rooms, the LEED calculation is based on women using the low-flush option three times a day and the full flush once a day.
http://www.psdmagazine.com/ASPE_memberpdf/20060304/PlumbingTechnologyoftheFuture.pdf
This is information that is not in the reference guide. Can anyone find another source to verify this? I find it strange that it is not equivalent to the male usage of urinal & toilet flushes.
Does any one have a sample question about this credit using flow and flush calculations?? or any one can explain this to me… =S I will be very grateful!!! =) tks
I found this question in a PPI exam: “The number of FTE building ocupants must be used consistently in calculation for which of the following LEED-NC credist? (choose two)
A) SSc4.2, alternative transportation
B) SSc4.4, alternative transportation
C) WEc3.1, Water use reduction
D) EAc1, Optimize Energy Performance
The answers are A, and B, but I think is something wrong because you use FTE calculations in WEc3.1 also and this could be an answer too or am I wrong?
http://www.gbci.org/DisplayPage.aspx?CMSPageID=22#Beta_Testing
CHECK THIS OUT!! if you are not certified still
@ Richard
You have to achieve 3 out of the 4 for SS credit 4 before you can apply for ID credits for SS c. 4
Arpita,
Where did you obtain that information from?(3 out of 4 to obtain ID credit for SS4)
Sorry Arpita please disregard my previous question!
I’m taking the exam tomorrow morning!!
I’m still having a hard time distinguishing between WEc2 and 3.1/3.2. Others have asked a similar question. I know that WEc2 has to do with “innovative wastewater technologies” and includes treating wastewater to tertiary standards, and WEc3 doesn’t deal with that. Let me put it this way:
How come if you reduce water use by 50% on WEc2 you don’t automatically get WEc3.1, 3.2 and exemplary performance for +40% reduction?
Anyone?
I believe the difference is,
Credit 2 option 1 wants you to reduce the amount of potable water turned into black water (building sewage) against a baseline by 50%
toilets and urinals involved.
Credit 3 wants you to reduce 20% potable water against the baseline
toilets and urinals involved AND
kitchen sinks, conventional lavs, showers
So it is more than likely that you would achieve atleast a 20 percent reduction (Credit 3) in water use if you met the requirements for Credit 2. With sinks, lavs and showers factored in, it may not be a sure thing that you would get a 30 or 40 percent reduction.
Its also possible to meet the requirements of Credits 3.1 + 3.2 and not meet the requirements of Credit 2.
These quotes are taken from pg 130 WE 2…
“For instance, water efficient water closets, urinals, shower heads and faucets not only reduce potable water demand but also reduce blackwater volumes created.”
“Thus, performance results will often overlap with those of WE Credit 3”
Hope this helps!
David