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The EPA WaterSense methodology and calculator allows only certain types of irrigation to be assigned to certain vegetation types. Why is this and won’t it skew results?

What if we just have a little green area on our rooftop? Is there a minimum amount of landscaped area to earn the prerequisite and credit?

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NC-v4 WEp1:Outdoor water use reduction

Water Sense Calculator

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Robyn Dowsey
Owner
Eco-Build Strategies LLC
LEEDuser Basic Member
15 thumbs up

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 Thanks

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Mon, 10/26/2015 - 21:31

Hi Robyn, 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!
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Robyn Dowsey
Owner
Eco-Build Strategies LLC
LEEDuser Basic Member
15 thumbs up

Tue, 10/27/2015 - 19:01

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.
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Ben Stanley
Senior Sustainability Manager
WSP - Built Ecology
LEEDuser Expert
188 thumbs up

Tue, 11/03/2015 - 18:55

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 irrigation 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

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