No Potable Use or No Irrigation
Intention:
- Limit or eliminate potable water (drinking water) use for landscape irrigation.
- Limit or eliminate use of natural surfaces for landscape irrigation.
Implementation:
- Option 1: do not use any potable water
- Option 2: do not use any irrigation system
- For landscaping, use following methods:
- Captured Rainwater
- Recycled wastewater
- Recycled graywater
- Treated water
- Minimize site area by:
- limiting turf areas
- using landscaping that doesn’t require permanent irrigation systems
- temporary irrigation ok (for plant establishment) if removed after 1 year of installation
- mulching & mowing
Codes/Standards Applied:
- none
Extra Credit:
- none
Submittal Phase:
- design
Links from Reference Guide:
- Graywater Systems, Compost Toilets, & Rain Collection
- The Irrigation Association
- Texas Evapotranspiration Association
- Texas Water Development Board Web Site
- Water Wiser: The Water Efficiency Clearinghouse
Other Water Efficiency Credits
- WE 1.1 – Water Efficient Landscaping – Reduce by 50%
- WE 1.2 – Water Efficient Landscaping – No Potable Use or No Irrigation
- WE 2 – Innovative Wastewater Technologies
- WE 3.1 – Water Use Reduction – 20% Reduction
- WE 3.2 – Water Use Reduction – 30% Reduction
44 Comments On This Post
Thanks for pervious answer.
If one project’s landscape can have no potable water use(means reduce by 100% > 50%), so it can get the both WE1.2 credit and WE1.1 credit. Is this right?
Thanks
Pat,
I found this answer. WE1.2 is the additional point to WE1.1. So once achieve WE1.2 should also achieve WE1.1.
Thanks
In the Reference Guide, they show example calculation tables for both the baseline case and the design case. Is it required to complete these tables for your project and submit them as part of the credit submittal process? The submittal template and the reference guide do not specifically say that they are required, but then why do they show the examples? Just for clarification of calculation method?
Does green roof irrigation count for the water efficiency credit? For instance, if everything on a site will be non-irrigated except the roof. Is it possible to still get eh WE 1.1 and 1.2 credits?
Pat,
As part of a CIR – WE c1 Ruling on 12/13/2007, the answer includes…
It should be noted that, in addition to using only non-potable water for irrigation, the project must demonstrate a 50% reduction in total irrigation water consumption from a baseline case in order to earn both WEc1.1 and WEc1.2.
This should contribute to answer fully Chen’s question
Any comments?
Anyone know where the .6233 in Equation 3 comes from?
And do they leave CE out of Equation 5 because conventional irrigation systems don’t use controllers? (i.e. Son, go out and turn on the hose.)
Gary
I would guess that leaving the CE out of EQ5 is basically giving you a chance to get some advantage out of using a controller. Much like a lot of the differences btw design/baseline cases in EAc1, where they allow the baseline building to be somewhat generic instead of making you model all of your design-case energy savings into the baseline.
Thanks Melissa. Any ideas about the .6233?
Gary
Nope. That one is a complete mystery to me.
Thanks anyway.
When are you taking the exam? Soon right?
Gary
tomorrow! I feel like my brain is full.
Good luck you two! Thanks for asking/answeing questions – you’re helping more than yourselves!
Again, good luck!
Thanks! Looking at other peoples’ questions is really helping me (I think. I hope.)–it leads me to go back and look again at a lot of the info., and definitely makes me think about aspects that I wouldn’t have considered otherwise.
Can someone explain to me what is meant by the baseline rate for the water use reduction precentage?
Cheers!
Ref. Guide v. 2.2, p. 123 Step 2 says to set the Species factor, density factor and Irrigation Coeficient to average values representative of conventional equipment and design practices. Use the same Kmc and ET0 as for the Design Case. Re-solve equation 5. (notice you leave out the CE).
Hope this explains it.
Gary
the submittal sample template from the usgbc website effectively asks for 4 options under WE1 (for WE1.1 and 1.2):
1. The landscaping and irrigation systems have been designed to reduce irrigation water consumption from a calculated baseline case (1 point).
2. The irrigation water used on site is supplied by a non-potable source (1 point).
3. The landscaping and irrigation systems have been designed to reduce irrigation water consumption from a calculated baseline case, AND the irrigation water used on site is supplied by a non-potable source (up to 2 points).
4. The landscaping installed does not require permanent irrigation systems. Temporary irrigation systems used for plant establishment will be removed within one year of installation. (2 points).
options 1, 3 and 4 make sense to me in that they are in line with the reference guide (2.2, v.3), but option 2 seems to be an additional option, which in the current reference guide seems to have been rolled into option 3.
can anybody clarify? or have the templates been overhauled (and are only accessible if you have a live leed project)?
thanks.
Answer to Gary’s Sept. question about .6233 for others (since he by now has probably moved on) The .6233 is one square foot of one inch of water measured in gallons. There are about 7.48 gallons of water in a cubic foot so divide by 12 to get this number. buzz
Buzz,
Thanks for answering that question. I passed the exam Friday, Nov. 21, and I’m happy to say that there were no questions about that. Ha!
Thanks,
Gary
Has anyone noticed in the Reference Guide sample that they are not using the Conversion (.6233 gal/sf/in) to come up with TWAP? The answer they are coming up with in the sample isn’t in gallons but SF-In… does that make sense or should just forget about this .6233 business. I’m looking at V2.2 3rd edition page 123 and 124. I spent 30 minutes trying to solve the problem using equation 3 to find that they weren’t actually using that conversion factor. Is there an Errata out there for this?
Thanks,
Vernon
That’s TPWA…
Vernon,
If you are concerned about preparing for the exam, the exam won’t ask you to calculate that formula, nor will it ask you to regurgitate the .6233 “business.” Good luck.
Gary
Did somebody know how you get CE value for the equation on how to calculate TWPA?
Thanks
Isabel,
The way the Controller Efficiency (CE) is determined for WEc1 calculations, is explained in the Ref. Guide NCv2.2 (3rd. Ed)pg 122. You basically get this info. from the weather-based controller mnfr. or landscape architect. This factor is not shown in the examples in the ref guide. In preparing for the exam, I looked at very technical info. in The engineering guide to LEED by
L. Haselbach where I found the answer to your question. Is unlikely that the questions on the exam are this technical.
Good Luck!
Ernesto Infante
Hi,
One of the requirements for this credit is to minimize TURF? Can someone tell me why not to plat alot of TURF?
Stefan,
Per LEED NC Reference Guide Third edition page 119, it states under “2. Practical turf areas” as recommended design approach.
Reason behind it (I think) is turf need to be constantly irrigated & maintained frequently (as compared to native/adaptive plants), has higher “Specie Factor (ks)” on page 121 & 122 table 1; thus contributing to more demand of irrigation water use.
Dude,
Thank you so much for breaking it down for me. It makes sence. Thanks. However, in place of TURF, what can we use? For instance, should the entire landscaping be native/adaptive plants?
Hi Stefan,
As an alternative to turf/high maintenance ‘grass’, you can consider using ‘xeriscape’ which I believe was in one of the practice questions. More on xeriscape, you can get a quick read by
ttp://home.howstuffworks.com/lawn-garden/professional-landscaping/alternative-methods/xeriscaping2.htm
Maybe you can employ hardscaping area to reduce the turf area (which may contribute less irrigation but may affect stormwater runoff), but with all the LEED credits you should consider both good & bad synergies anyways.
I hope this can jog some idea to your question.
A practice exam states:
Which 3 might contribute to WEc1:Water Efficient Landscaping?
A. planting of hardwood trees to provide shade
B. use of native or adapted species
C. substitution of turf grass for other types of vegetation
D. reduction of total landscaped area
E. a combination of vegetated swales and rain capture
Correct Answers: A, B, E
Is C not a correct answer b/c it says “other types” and would only be correct if replaced w/ native/adapted species?
And for answer E, I understand the rain capture, but how does vegetated swales contribute. I don’t find anywhere in the manual where it talks about them under WEc1.
thanks Yuki. It helped alot. thanks for your time.
What are the prerequisites for Water Efficiency?
there are no prerequisites for WE
I came across “alternative mowing” can anyone help me please 🙁 how does it work?
Cassi-
The way i read it is that C is not correct because it is suggesting one replace other plants with turf grass- what one should do is the reverse (badly worded I think also)
I also dont understand about the swales. Anyone else?
Another sample question:
Points are awarded in WE Credit 1.2, Water Efficient Landscaping: No Potable Water Use or No Irrigation, for which of the following? (Choose 1.)
a.Drawings and a narrative documenting and describing a captured rain system; irrigation use reduced by 100%.
b.Cut sheets for high-efficiency irrigation equipment and calculations demonstrating potable water consumption by occupants
c.A design narrative of the landscape design and a description of why a permanent landscape irrigation system is not required
d.A water budget calculation demonstrating that occupancy-based potable water consumption has been reduced by 30%
Answer given is a. I dont understand why the answer is not c (ie- no irrigation. I dont see anywhere that drawings are required for submission for this credit.) Any thoughts?
Jessie-
Wow, i hope the questions on the test aren’t as unclear as this one. The only thing i can think of to explain why ‘A’ is better than ‘C’ is this:
Drawings aren’t required, but calculations ARE required. ‘A’ doesn’t specifically mention calculations, but it is implied by saying “reduced by 100%”… ‘C’ is just giving a narrative, but no calculations.
Does that make sense?
Melissa- What do you think you do if you have NO irrigation (which is the second option for 1.2. DO you think you still have to calculate all TWA etc and show that it is 0? That doesnt make sense to me . .
All but which of the following are regional issues for a design team to be aware of in implementing a rainwater harvesting system (choose 1)
a. Native vegetation
b. local precipitation levels throughout the year
c. local health codes
d. supply water quality
Ans: a.
Can anyone explain?
Stephanie:
Local precipitation affects feasibility of collecting a sufficient volume of rainwater (if it doesn’t rain often, the system won’t collect enough water to reduce potable water use;
Local health (and building) codes in some states prohibit the use of harvested rainwater systems (so it’s important to check before including in design).
Supply water quality must meet standards established by manufacturers for specific fixtures (if quality is unacceptable, it could compromise long-term performance).
All of this is discussed in WEc2 “Regional Issues” on pg. 136 of the Reference Guide, 3rd edition.
Thanks Sara!
Why does LEED give credit for “no” irrigation? Most plants (even natives) benefit from some supplemental irrigation from time to time.
Do they also give credit for “no” air-conditioning?
JDG,
WEc1 credits in general deal with issues concerning use of ‘potable water’ for irrigation. Reduce 50% and they will give you 1 points. Reduce 100% and they will give you 2 points.
EAc1 and EQ credits deal with strategies recognizing the use of ‘natural’ ventilation (no A/C.) instead of mechanical A/C.
My 2 cents
I’m confused, is there a minimum area required for landscaping? lets say I”m in an urban site and have two trees in the front of the building- if I only water them for one year does this qualify for 1.1 and 1.2?
Hello,
Thanks for all the helpful posts. I’ve found answers to many questions here. I have run across what seems to me to be a discrepancy in the LEED 2.2 Ref Guide WE c1.2 Calculations section w.r.t info in the same 1.2 Requirements section and hope someone can shed some light …
WE 1.2 Calculations (page 123 in Ref Manual) I would have expected to have dealt with the “OR” case of the Requirements, but instead say “If the Percent Reduction of Potable Water is 100% AND the Percent Reduction of Total Water is equal to or greater than 50%, WE Credit 1.2 is earned in addition to WE Credit 1.1.”
However, there is no mention in the Requirements section of WEc1.2 to reduce *total* water consumption by 50%. The last part of Requirement 1.2 talks about landscaping that doesn’t require any water after a year. The calculations don’t even mention this part of the 1.2 Requirements, and the 50% reduction in total water use is not a reflection of WE c1.1, since WE c1.1 is only dealing with *potable* water use.
Thoughts?
Thanks.
One simple question
Any type of grass including turf grass,
don’t meet the requirements of native and adapted vegetacion in all LEED credits?