The big question for this credit is how your team will demonstrate compliance. Though this credit is similar to the LEED 2009 credit that addresses landscape irrigation use, the v4 iteration stipulates different compliance paths depending on the conditions of your building’s systems.
The first and easiest path is when landscaping does not require irrigation. If not, the credit is yours via Option 1.
If your landscaping does require irrigation there are two separate paths to compliance, depending on whether or not you have irrigation metering installed. (Teams should also know that projects with no landscape areaThe landscape area is the total site area less the building footprint, paved surfaces, water bodies, and patios. automatically meet Option 1 and earn the credit.)
For Option 2, if your site doesn’t have an irrigation meter, you need to calculate the expected landscape irrigation reduction using the EPA WaterSense Water Budget Tool. Most landscapes that use basic water conservation strategies such as low water vegetation, 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., and WaterSense controllers are likely to meet the 40% reduction threshold. The catch is that the project must also install an irrigation meter before the performance period ends in order to earn the credit.
If your site already has an irrigation meter you must pursue Option 3, and it will likely be much harder to demonstrate compliance with the credit threshold. In this case your performance is calculated based on a straight reduction from your historic metered water usage. If your team has made efficiency improvements to the irrigation system recently, this credit may be good to pursue.
The required savings can be achieved via any of the available water reduction strategies listed in the LEED Reference Guide, including alternative water sources.
Teams can choose to use the EPA or USGBC tool to complete the calculations for Option 2. This is confirmed on the v02 form for this credit posted on USGBC’s website.
No, there is no minimum amount of vegetation identified in the Rating System or Reference Guide. In fact, the Reference Guide states that projects that have no landscape area automatically meet the requirements.
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.
If landscape irrigation is not submetered, use Option 2.
Show that the landscape does not require a permanent irrigation system beyond a maximum two-year establishment period.
Use the existing landscape to calculate the landscape water requirement using the EPA WaterSense Water Budget Tool.
Install an irrigation meter.
The baseline is established using the annual average of at least 3 years of consecutive data out of the last 5 years.
Points are earned according to Table 1.
Demonstrate a reduction in outdoor water use over the most recent 12 months compared with the established baseline. Points are earned according to Table 1.
Complete documentation for achievement of WEc - Outdoor Water Use Reduction on the LEED v4 O+M:EB Platinum StopWaste.org headquarters office building at 1537 Webster Street, Oakland, CA. Project documentation was shared with LEEDuser through cooperation with that organization, and the LEED consultant, BuildingWise LLC
This calculator is recommended for use by teams for projects outside of the U.S.
Project teams can use The WaterSense Water Budget Tool to comply with section 4.1.1 of Version 1.2 of the WaterSense New Home Specification, or to ensure a measure of efficiency and regional suitability for the amount of water applied to a landscape based on local climate data.
i am working on the project where project team use the STP Non 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 for irrigation purpose. so i am reducing the 100% potable water. can i sufficient to achieve this credit.
If the STP non-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. qualifies as an alternative water source per the reference guide language then yes, this approach would work to achieve the credit.
I noticed the worksheet has some errors:
a) "Baseline Calculation" tab: the Watering Demand column is subtracting rainfall from ETo, instead of ETo being subtracted from rainfall
b) "Baseline Calculation" tab: Cells E22-E24 look incorrect - they are the minimum instead of the maximum
c) "Landscape Water Requirement" tab: Looks like the Average Monthly Rainfall for Peak Watering Month is referencing the lowest month
Is there someone to check the worksheet thoroughly and make corrections?
I'll try to address your questions below:
a) Based on the most recent v4_Outdoor Water Use Reduction Calculator I downloaded from the resource page, the watering demand column appears to have the correct subtraction method. I see the ETo being subtracted from the rainfall to calculate the watering demand (D10 - C10 = E10).
b) I see in the spreadsheet formula that they are pulling a minimum, but it is pulling the data from some hidden columns that I can't see. I've entered in some examples from previous projects and it seems to pull the correct peak watering month based on the rainfall and ETo data.
c) Depending on if the formula for peak watering month in the "Baseline Calculation" tab is correct, this also appears to be correct once I enter in some sample data.
Let me know if this helps or if you have any other questions.
The resources link for this credit directs us to use the ETo software calculator from the FAO website:
Previously I have used the WaterSense website to get ETo data, but after pressing the "go" button, the data does not pop up anymore:
In lieu of the software, would it be acceptable to use this source to gain ETo data? After entering the latitude and longitude of your site, the ETo is provided with fewer steps than the software. It looks like it uses the Penman-Monteith equation like the above software does, but without the ample technical jargon.
Are there any concerns with using the IWMI to get ETo data to satisfy this credit?
We have started to utilize the IWMI Online Climate Summary website for several pieces of climate information, one being ETo. I definitely agree with your statement about this website being much simpler to use than other sites, and their methodology is solid. You should be fine using the IWMI site for your ETo data.
If we install subsystem metering for the irrigation systems to comply with WE credit Water Metering can we still select Option 2 (No irrigation meter installed: Calculated water budget).
Alternatively, we cannot select Option 3 (Irrigation meter installed) because historical data are not available since the subsystem metering was installed only prior to commencement of the performance period. Any thoughts?
If you do not have the historical meter data for the required three years, then you can pursue Option 2. The calculated water budget would be utilized for the initial certification and Option 3 would be utilized for recertification.
You can find this in the reference guide under Step 4 of the step-by-step guidance.
Thank you Edward!
Does the 30% reduction need to be accomplished through landscape efficiency first and then add up alternative water sources, or may this be accomplished through any landscape irrigation means (alternative water sources, irrigation controls)?
The 30% and 40% reduction can be accomplished through any means, including alternative water sources, smart irrigation controls, or just by reducing the overall irrigation needs by adjusting the landscape design. There's no requirement to achieve one method before additional savings can be applied.
Does reclaimed water used for irrigation need to be submetered?
It is not required to submeterSubmetering is used to determine the proportion of energy or water use within a building attributable to specific end uses such as tenant spaces, or subsystems such as the heating component of an HVAC system. reclaimed water that is utilized for irrigation. However, if you are claiming the use of alternative water in the calculations, you will need to provide proof supporting this amount. LEED states that they need to see calculations or other supporting documentation to confirm any use of alternative/reclaimed water. This documentation could be meter readings if the reclaimed water is submetered. SubmeteringSubmetering is used to determine the proportion of energy use within a building attributable to specific end uses or subsystems (e.g., the heating subsystem of an HVAC system). the reclaimed water will ensure your numbers are the most accurate, just know that you will probably need at least a years worth of data to establish a good baseline. The reference guide also provides calculations if you are collecting rainwater. If you happen to be collecting water from other sources (cooling tower blowdownAlso referred to as bleed-off; the removal of makeup water from a cooling tower or evaporative condenser recirculation system to reduce concentrations of dissolved solids that can cause mineral buildup., condensate, other sources), you will need to provide your own calculations that can backup what you are claiming in the calculator.
Hopefully this helps you out a little bit. Depending on what kind of reclaimed water system you have in place, you have a couple options when it comes to claiming this reduction in the calculations.
Is this still relevant for v4 EMOB?
Reclaimed water used for irrigation is submetered from potable building use.
Do we just need to provide the submetered irrigation numbers for one year?
I would say a year's worth of irrigation numbers at a minimum, but three years would be ideal.
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