Hi All,
I have a very foundatmental question:
In the Outdoor Water User Reduction Calculation, we have to fill in the landscpe area of different plant type: trees, shrubs, groundcover, turfgrass. My question is how to determine the area of "trees", by its cross-section area of tree truck? coverage of canopy? or roots? And it is mostlikely that the there will be shrubs or groundcover under the canopy, what plant type should be classified in those area (e.g. area covered by both shrubs and tree canopy).
Thanks a lot!
Emily Purcell
Sustainable Design LeadCannonDesign
LEEDuser Expert
370 thumbs up
January 5, 2022 - 6:07 pm
I have never really found a good answer to this one! In my experience, the landscape architect doing the calculation has most often used the groundcover (i.e. shrubs or turf grass) and left the tree category out of the form entirely. If there are trees standing alone in street grates, they would use the ground area of the grate as "trees." But I don't believe there is any hard and fast rule about this, and I have never had a review comment saying that area should be classified differently.
One note, this can create inconsistency with the open space / habitat restoration credits! For example, if I have 1000 sq ft of turfgrass with trees planted in it, the landscape calculator might say "1000 sq ft of turfgrass" while the open space calculator says "1000 sq ft of mixed vegetation." I haven't had that be an issue in a review as long as I make a note of it and explain the reason.
emily reese moody
Sustainability Director, Certifications & ComplianceJacobs
LEEDuser Expert
476 thumbs up
January 5, 2022 - 6:30 pm
Hey all,
You could pretty safely refer to the guidance under the Heat Island Effect credit, which states the following for calculating SF (pg 202 of the PDF, or Table 3: Nonroof Strategies):
"Assume 10-year canopy width at noon (i.e., in plan view, plant canopy width has no extending shadows, regardless of time of year)"
It was previously 5 years in v2009. I think I've only been dinged on it once when we got a little too creative with determining the shaded area.