This prerequisite requires teams to design water-efficient landscapes, and encourages a multi-faceted and integrated approach. Outdoor water use is impacted by vegetation type, vegetation density, overall planted area, and irrigation efficiency, so consider all of these variables in approaching prerequisite compliance.
Minimizing turf grass, installing native and drought-tolerant plants, and using efficient irrigation systems will typically align with meeting the prerequisite requirements.
A landscape design that does not require permanent irrigation is the most straightforward way to earn this prerequisite, as long as programming and operations and maintenance practices align with a non-irrigated landscape.
The type of irrigation that can be assigned to certain vegetation types is pre-determined in the calculator, limiting user ability to make adjustments that might better reflect the design conditions. This is likely based on EPA’s assumptions about potential changes to the irrigation system and future use. 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). has not provided a work-around for this yet, so if you are concerned about the methodology not accurately reflecting project conditions to a degree that impacts your ability to meet the prerequisite, consider submitting 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 proposing an alternative compliance path.
There is no minimum landscape areaThe landscape area is the total site area less the building footprint, paved surfaces, water bodies, and patios. to earn the prerequisite or the credit.
One could argue that this discourages landscaping, but according to USGBC, hardscapes are addressed and, one could argue, discouraged by other credits, so this is considered a fair approach.
To reduce outdoor water consumption.
Reduce outdoor water use through one of the following options. Nonvegetated surfaces, such as permeable or impermeable pavement, should be excluded from landscape areaThe landscape area is the total site area less the building footprint, paved surfaces, water bodies, and patios. calculations. Athletic fields and playgrounds (if vegetated) and food gardens may be included or excluded at the project team’s discretion.
Show that the landscape does not require a permanent irrigation system beyond a maximum two-year establishment period.
Reduce the project’s landscape water requirement by at least 30% from the calculated baseline for the site’s peak watering month. Reductions must be achieved through plant species selection and irrigation system efficiency, as calculated by the Environmental Protection Agency (EPA) WaterSense Water Budget Tool.
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.
Under Option 1 are vegetated (green) roofs considered as part of the landscape that requires (or does not require) a permanent irrigation system? Under Option 2 are vegetated roofs to be included in the calculations? This is for both the Prerequisite and the Credit for Outdoor Water Use Reduction.
Good question. Is your vegetated roof used as a food garden? If so, the reference guide says this vegetation can be included or excluded at the project teams discretion. However, if the vegetated roof is not used exclusively for growing food, it would need to be included in both the credit and prerequisite.
I hope that helps!
there is a minimum of green area (landscape) to comply with the outdoor water use reduction?
in v3 I understand should be at least 5% of LEED Boundary.
There is no minimum landscaped area required to comply with the Outdoor Water Use prerequisite or credit. If the site does not require irrigation the project will automatically earn the prerequisite and points for the credit. Ensure you choose the right option within the prerequisite/credit that fits the irrigation needs of your project. Option 1 is better for projects that do not need permanent irrigation beyond an establishment period, and Option 2 should be chosen if there are irrigation needs on site outside of an establishment period.
I hope this helps!
I got the following question/comment from a reader who is a landscape architect. Does anyone have any thoughts? Here is the comment:
The concern is that this tool was designed for a homeowner. Since we work on large commercial projects such as an airport campus, there are fundamental problems with how the calculator works.
For example: To avoid needing irrigation, we have planted our turf areas with a species that is native to the area (Florida) and does not require irrigation. However the calculator makes us treat this area as spray irrigation (the most inefficient) rather than rotors, or better yet, recognizing that we are selecting species that do not need irrigation. The rational is that someone may sell the house and put in irrigation.
Obviously, no one will be selling an airport. Since the overall goal for this section is to reduce 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, the process should recognize that we are selecting a turf species that does not require irrigation and give us credit for it and not penalize us by making us calculate it as the most inefficient irrigation allowed. It should at the bare minimum allow us to use the calculations for rotors, since this is the common method for large commercial projects.
USGBC needs to modify the way this is calculated for large jobs and campus wide certifications.
curious if you have heard back from USGBC or anyone else regarding the use of the Watersense tool for large/non-residential projects.
I got a reply Deborah-
Robyn, can you share what it was? thanks!
My apologies Tristan - Debra and I know each other so I knew she would reach out to me offline.
That said below is an explanation of the challenge and the steps towards resolution.
Based on my conversations with National and my continued understanding of the credit intent, a special approach was taken towards credit compliance. The utilization of the calculator was utilized and uploaded as part of the documentation for the credit.
Though needed, it is not the only piece of documentation needed and as with all things USGBC it is the outcome and not the path to get there that is important. The team recommended a strong narrative justifying credit intent along with a clarification of how the calculator should be used. I have found that a strong narrative can be a vital part of the compliance documentation process.
Large project challenges -
Most larger projects utilize turf grass (sod) to be able to provide stabilization for large open space areas developed that do not have structures on them, as a cost effective means of addressing the areas. On the other hand, the calculator is being used to encourage projects to utilize ground cover and other stabilization means (implementing good LIDLow-impact development: an approach to managing rainwater runoff that emphasizes on-site natural features to protect water quality, by replicating the natural land cover hydrologic regime of watersheds, and addressing runoff close to its source. Examples include better site design principles (e.g., minimizing land disturbance, preserving vegetation, minimizing impervious cover), and design practices (e.g., rain gardens, vegetated swales and buffers, permeable pavement, rainwater harvesting, soil amendments). These are engineered practices that may require specialized design assistance. practices), to reduce the need for water at all (whether reused or potable). Larger projects can have a huge number of acreage that have to be destabilized in order to accommodate underground utilities and roadwork that can be cost prohibitive to many of the alternate strategies.
The water sense calculator (as stated above) is for smaller lots where the calculator assumes will be very public and well viewed. Even if an owner states they will not irrigate these areas, having a space close to your building or house that is brown or in poor health doesn't leave a great impression on those looking at it. Because of this many owners who originally intended not to use irrigation put them in after they see how bad the turf grass will become. It is because of this that the calculator states that you must include irrigation on any landscaped area.
To address this challenge, the following steps were taken -
1. The LEED v4 calculator was used - This calculator is more applicable then the one direct from Water Sense version.
2. The calculator was run twice;
Once with the prescribed irrigation type for no landscaping and once with no irrigation selected. An average of the two was used to support percentages achieved.
3. A detailed narrative was included along with owner support stating that in the area in question, that the turf was being used for stabilization and not beautification. Brown grass was acceptable and would not need remediation or future consideration of irrigation.
Keep in mind that on this project, strict Low Impact Development strategies were evaluated and used in most building local areas. Only in the large stabilization areas did conflict present itself and that is what allowed for credit intent conformance without perfect calculator compliance.
I hope this helps our readers to better understand the challenge and the solution.
Wow, thanks for the detailed followup! This will be helpful for others.
does anyone try to use the spreadsheet updated on 4/5/2016?
In the "Baseline Calculation" sheet, errors occur at anytime I tried to fill in a value under "Monthly Rainfall" or Monthly ET0".
Macros are enabled and I'm wondering if I'm missing something or if there is some problem within the spreadsheet.
Thanks in advance for your help. I really appreciate it!
Are you using the EPA Watersense water budget tool that you can download at this link?:
Try downloading the latest version and let me know if that addresses the problem.
the project I'm working on is in Italy so it is recommended to use the LEED v4 Outdoor Water Use Reduction Calculator you can find at this link;
I heard other people who have encountered the same problem, I hope It will be fixed soon.
Thank you for your suggestion.
I downloaded the calculator from USGBC (updated 4/5/2016) and did not encounter an error when entering rainfall and ETO. If you continue to encounter errors, please let me know and I will do my best to bring this to the attention of the USGBC. In the meantime, other than lacking the option to enter data in SI or IP units, the EPA Watersense calculator appears to be equivalent, so you could convert the data and use this.
Thank you Alan, I unlocked the spreadsheet just to understand where was the problem and I found that the Excel function "RANK" under the hidden column G was not recognized by the Excel Italian version which required the same function to be written in Italian...
Anyway, thank you for your support.
I am performing the calculation for the Water Outdoor Prerequisite, with both excel for a Project located in Italy (Rome):
1. Water budget tool (downloaded from EPA)
2. v4_Outdoor Water Use Reduction Calculator
I get a negative value for LWRLandscape water requirement: the amount of water that the site landscape area(s) requires for the site's peak watering month., I suppose that for this reason I don't need any irrigation, is it true? Does anyone have experience on that?
A negative value for LWRLandscape water requirement: the amount of water that the site landscape area(s) requires for the site's peak watering month. likely indicates an error in data entry to the calculator. The values for both LWA and LWR should both be 0 or higher. With additional information, we may be able to help you pinpoint the source of the error.
Does the storage of rain water contribute to achieve this prerequisite?
The project will irrigate the outdoor vegetation only with rain water. Nevertheless, the water reduction in term of water volume, in comparison with the baseline, is only 16%.
Is it acceptable?
Unfortunately, the v4 reference guide states, "Additional savings gained by using alternative water sources and smart sensor technologies are addressed in the WE Credit Outdoor Water Use Reduction. No credit is given for alternative water sources in this prerequisite." You will need to meet the 30% reduction using the EPA WaterSense tool and then the alternative water sources can be used to demonstrate compliance with the WE Credit Outdoor Water Use Reduction.
Hope that helps!
Hello everybody. In our project we do not have outdoor water use except for irrigation. Knowing that only the municipality recycled water is used for irrigation, does this secure 2 points of the credit (i.e. 100% outdoor water use reduction)?
Though I'm sure one of the LEED User family will respond to you I wanted to provide my understanding and some thoughts on the matter. From your question I assume you are seeking certification under V3. If V3 then the my understanding is that the reclaimed water would meet the 2 point requirement without any modification to the design. That said before your team moves forward with that understanding it might be fun to take some queues from the new version of LEED v4. The new version of LEED helps team understand that just using reclaimed water really isn't helping our overall objectives to reduce impact. It asks them to stretch their muscles and really develop a low impact landscape design, using low water tolerant plantings, reduce turf areas, incorporate sheet flow and terrain features into their design so that they can reduce water even if it is reclaimed water is being used. By creating a basic palate that requires less water no matter what the water source is. Unfortunately even reclaimed water is a precious resource. Keep in mind most reclaimed water is developed with a carbon footprint that uses energy and other resources even if it isn't potable. For V4 the reclaimed water option would achieve the credits but not the new pre-requisite. If you haven't read or learned about the new version yet its worth looking into as it really caters to international certifications such as yourself.
Hope this is helpful
Thank you Robyn. Sure your reply is helpful for me.
Actually we are seeking LEED V4 not 3, and it seems I posted my question here by mistake as it should be in the relevant credit not prerequisite.
And yes I have not quite learned what is new in LEED V4 and I have to do. Thanks for warming me up :)
Now to sum up what I understood:
- The credit is concerned with water reduction in general regardless whether it is potable or not.
- Using recycled water only in irrigation does not mean 100% reduction of water use.
- What contribute to the credit is water reduction resulted from using native plants and efficient irrigation system. This reduction to be calculated with comparison to the water use baseline.
The calculator says that acceptable irrigation types for landscaped turf grass is only drip and fixed spray but allows rotors in the drop down- can rotors be used or not - Kind of urgent
The calculator is very unclear, however, because all irrigation types are checked as appropriate for turfgrass in Table 4 I would assume that the rotor is also appropriate. Because it has the same efficiency as many of the other irrigation techniques it would seem odd for them to un-include the rotor. In previous versions of LEED rotors were allowed to be used for irrigation, and I don't believe that has changed. I think the calculator error was merely an oversight.
Hope that helps!
Thank you Kimberly
Unfortunately we still have interpretation issues
The water sense calculator says that non-irrigated turf still must be shown within irrigation type
if you put in the fixed-spray which is the only option allowed for non-irrigation and use the rotor heads as you have suggested for the irrigated areas then irrigated becomes less impactful than non-irrigated
This seems to be the opposite of what we want teams to do
Here is a better explanation:
The reference guide and the calculator seems to dictate that there are specific types of irrigation allowed for different plant types for both irrigated and non-irrigated areas
In our case the turf grass areas are both irrigated and non-irrigated areas
The irrigated turf area is using rotor heads listed as an EU of 70 and the non-irrigated area if we use the assumption box must show fixed spray with an EU of 65. In addition, the rotor heads being used on the project are not listed in the appropriate irrigation types in landscaped areas as an option - only fixed or micro spray but is an option in the calculator drop down options so we are confused what to use.
Since the reference guide specifically (page 261) states that no area that is landscaping can show zero water use, my thought would be to pick another approved option with a 70EU but either way that would make the non-irrigated area more water intensive than the irrigated area which doesn’t make sense.
It looks like the Watersense Water Budget Approach requires that non-irrigated turf areas be listed as using the fixed spray to account for the possibility that the property is sold and that irrigation could be subsequently installed. Since the rating system adopts the tool for the prerequisite, we're also adopting the required WaterSense methodology. Here's the language from the Water Budget Approach document from WaterSense.
"If irrigation systems are not being installed on the site by the builder, an irrigation type still must be designated for each plant type and any pools, spas, or ornamental water features. For low water-using trees, shrubs, and groundcover, standard drip irrigationDrip irrigation delivers water at low pressure through buried mains and submains. From the submains, water is distributed to the soil through a network of perforated tubes or emitters. Drip irrigation is a high-efficiency type of microirrigation. is assumed. For all other categories of vegetation, fixed spray irrigation is assumed. This is to account for the type of system that might be installed after the home is sold. For the same reason, if irrigation systems are only installed on a portion of the landscape (e.g., only on turfgrass but not on shrubs), the remaining portions of the designed landscape must use the same assumptions."
The Water Budget Approach mentions rotor irrigation specifically and so I don't see any issue with applying that irrigation type to the irrigated turf grass, despite the fact that rotor irrigation isn't listed in Table 4.
Here's a link to the Water Budget Approach http://www3.epa.gov/watersense/docs/home_final_waterbudget508.pdf
Both WEp1 and WEc1 state: "The following landscape types may be included or excluded from landscape calculations: vegetated playgrounds, athletic fields, food gardens, and urban agricultural areas." These types are not defined in the credit language itself; are they defined elsewhere?
I'm particularly interested in knowing what qualifies as a vegetated playground or athletic field. Average hours of use per [day/year/etc.]? Intent of the owner for how the space is used? Presence of permanent play equipment? Thanks for any guidance.
It doesn't appear that there's a set definition established, credit language indicates teams can choose to either include it or exclude based on their own reasonable definition/narrative.
What I am interested in and can't find an answer to is whether or not these excluded areas need to be also be excluded in other credits. This was the case in version 3, but in the version 3 reference guide there was also the language that stated specifically for school projects "...including playgrounds and athletic fields in this credit is optional. However, if such areas are included, they must be included in all other applicable credit calculations."
We have seen this go both ways (in version 3), where if a playground is excluded, we haven't been allowed to count that area in our open space credit. I can't find any similar language in the version 4 reference guide, so I am not sure whether I can expect to include or exclude our playground area in the open space credit.
I have two turf areas that will not be irrigated after establishment
My understanding is that for the water sense calculator you must model them with irrigation is they are landscaped
Is this true
Is this the only area on the site that will need irrigation? If so, I would recommend following Option 1 by demonstrating that the landscape does not require permanent irrigation beyond the establishment period. LEED sets the maximum establishment period to be 2 years.
If it is not the only landscaped area on site, the answer is yes, this area must be included in the water budget tool. However, the option can be chosen in the tool to note that those particular species need low levels of irrigation.
Hope this helps!
This is Josef Abboud from Atelier Ten
For outdoor areas within a renovation project scope (i.e. within the LEED boundary) but not scheduled for renovation or upgrade, do the water reductions required for this prerequisite apply?
Yes, for an NC project, the whole project scope is relevant for the prereq.
Hi! How is that projects outside USA may use the Excel (in the pr and cr resources) or the WaterSense tool if the Zip Code must be introduced?.
We have our own Eto Data and as we see we are not able to use de WaterSense Tool as it is only set for locations in USA and it does not work with International System which is as I remember well one of the exciting news about the globalization of LEED.
Thanks so much for any help provided.
The "International Tips" section of the LEEDv4 Reference Guide indicates that projects outside the U.S. should be able to input their ETo data directly into the tool. I downloaded the latest version of the tool from EPA's website (http://www.epa.gov/watersense/water_budget/) and Step 1B on the first tab asks for the average monthly reference ETo - you should be able to enter your value there regardless of your project's location.
I am gathering all the water use reduction points in v4. Besides the ones in Water Efficiency, are there any others that I am unaware of in sustainable sites, or energy and atmosphere, like activity pollution prevention as it relates to dust control? Thanks in advance for your help. I really appreciate it!
Check out IPc1. The most signficant water reduction credit in LEED v4, in my opinion.
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