Intention:
- Reduce wastewater generation
- Reduce potable water demand
- Increase the recharge of local aquifers
Implementation:
- Treatment system cycle: transport –> store –> treat –> dispose
- Option 1: Reduce potable water use by 50%
- use water conserving fixtures
- reuse non-potable water for flushing
- reuse on-site treated water
- Option 2: Treat and reuse 50% of wastewater on-site (to tertiary standards)
- treated water must be treated by:
- biological systems
- constructed wetlands
- high efficiency filtration system
- treated water must be treated by:
- For calculations, consider:
- Occupants: students, customers, visitors, FTE
- Male to Female water usage ratio: 1 to 1
- male:
- water closet = 1
- urinal = 2
- female:
- water closet = 3
- use per day
- male:
- usage rate
- occupancy
- number of workdays
Codes/Standards Applied:
- none
Extra Credit:
- Reduce (option 1) or Treat (option 2) 100% (instead of 50%) of potable or wastewater, respectively
Submittal Phase:
- design
Links from Reference Guide:
Other Water Efficiency Credits
20 Comments On This Post
for the option 2: how does it mean “to teriary standard”?
Tertiary Standards is a term usually used to define the requirements for recycled water that will be used for non-drinking applications. It may be, for example, the California “code” for recycled water.
Basically, its just making sure to treat the water per the applied codes. You don’t have to worry about those exact codes, though, for the exam.
I hope this helps!
Good luck!
What is the difference between WE 2 and CE3? They seem very similar by using high efficencey fixtures? Please explain.
WE 2 is among several credits that point out that “FTE calculations for the credit must be used consistently for all LEED-NC credits.” But it also says “In buildings with multiple shifts, use the number of FTEs from all shifts, since this credit is based on annual consumption.” In another credit (I forget where… one of the parking credits, I think–SS 4.3 or 4.4), it says to use the shift with the highest number of FTEs and to take shift overlap into account.
So how do you do this consistently?
(can anybody tell that I’m days away from taking the exam and am nit-picking the reference guide now….?)
@ Melissa,
I think its like this:
For things that deal with “static items”, like bike storage areas and parking spots, which will not change after project completion, you use the “highest number” FTE calculation. This is different than flushing and water fixtures, because how many times water is used, which is the thing we are concerned about here, is dependent on the number of people using it at various times, and to calculate this in a quantifiable way through LEED, it has to be done on an annual consumption basis.
Hope this isn’t confusing you. You are getting nit-picking with the reference guide, which is definitely a good sign. Good luck on your exam and best of luck to you!
-Pat
Within an hour of asking this question, I took a greenexamprep practice test with a question about calculating the FTE for a project with no parking requirement. And I got it wrong (sigh…).
Sorry..i just got home from work =/
I didn’t get it wrong because you failed to answer my question, I got it wrong because I forgot the fact that I had just read the words “use only the highest-volume shift in the FTE calculation.”
these FTE calculations are still throwing me! they are obviously different for SS and WE! to test my understanding, is the following correct?
under SS:
– calculate FTE using the highest volume shift where multiple shifts. but shift overlaps to be considered, when determining peak building users.
under WE:
– use FTE from all shifts (ie. sum)
– where transient occupancy, use transient occupancy number that is representative of daily average
– where both FTE and transient: water use to be calculated separately for each fixture for each occupancy type to represent unique use patterns.
correct?
Hi pat,
I’m curiouse about the exemplary performance criteria of reducing potable water by 100%! How is it possible to not use any potable water. Everyone has to drink, does bottled water not count?
I just took the test yesterday and passed with a pretty good score (thanks a great deal to this site!) and just wanted you guys to be sure you know all about this particular credit in case you get the same test I did. I had studied up pretty well on storm-water but my test concentrated on this credit instead. Mainly, know those strategies – for everything!!
Just found a question on the University of Florida exam that had a tricky question–wanted to share with the group. It asks about what credits a company might be eligible for if they treat gray water to secondary standards… It did not qualify for WEc2 because secondary is less than tertiary. For those of us not familiar with water testing standards (like me), this distinction is something to watch for.
For the purpose of the LEED exam only, is wastewater from a “kitchen” sink classified as “graywater” or “blackwater”?
This came up in a recent study group and the Reference Guide was of little help. By definition (page 137, third ed), not definitive for purposes of the exam. Also, pg. 405, blackwater (kitchen sinks) determined by local/state codes. Pg. 411, graywater (kitchen sinks) determined by UPC or IPC. Some states YES, some states NO.
I know I’ve seen the question on a sample exam where you were given several choices for blackwater fixtures. What answer does LEED want to see?
Also read somewhere that you need to “guess” what LEED wants to see as the answer, not necessarily what the actual answer should be…this has helped me considerably.
If there are three other correct answers do not pick Kitchen sinks.
If you picked two correct answers and kitchen sinks, water closets and urinals are your remaining answers then select kitchen sinks,
If you have to chose between kitchen sinks and kitchen sinks with garbage grinders… avoid the garbage disposal selection.
If you have to guess do not chose Kitchen sinks as greywater.
Tyler from 3 months ago, hope you figured out this distinction, but this credit is in regards to water used for sewage conveyance…go to WE3x for other water use reduction credits.
can you explain or tell me where to find the flow rate calculations for different fixtures. Also to clarify, transient users are calculated in the WEC2, correct?
A three stories office building with a capacity for 500 occupants has about a half male, half female demograohic. AS a base line case assume 260 anual workdays and a total daily volume of 2100 gallons, and no provisions for recycled wastewater. How many gallons of rainwater must be harvested per year to be directed to the wcs and urinalsfor flushing in order for the project to achiven WEc2 innovative wastewater technologies??
A. 2100 gallons
B. none
C. 546,000 gallons
D. 278,000 gallons
does anyone know why the answer is D and not C?
The requirement for WEc2 is to reduce demand by 50% — using the given info to calculate the baseline, the design case would need at least 273,000 gallons in order to achieve this credit. If the question asked for Exemplary Performance, then I believe it would be 546,000 gallons (100% reduction).
Thakyou very much Sara!!! that’s true!!! I forget the reduce demand by 50%
[…] Innovative Wastewater Technologies […]