Coefficient for pervious and gid pavers?

Nell Boyle

LEEDuser Basic Member

32 thumbs up

October 4, 2010

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Amy Rider

Sustainability Manager

KEMA Services

LEEDuser Basic Member

110 thumbs up

Thu, 10/14/2010 - 22:38

The coefficient depends on the kind of pavers. I would say a "grasscrete" paver with 1/3 vegetation and 2/3 concrete would have a weighted average of 0.66(0.95*2/3 + 0.10*1/3). Pervious concrete or pavers filled with gravel would be more similar to brick (0.85) in terms of overall permeability.

brian lutey

VP of Green Building

ozinga rmc

LEEDuser Basic Member

11 thumbs up

Mon, 05/21/2012 - 15:23

Amy, How did you come up with a coefficient of 0.85 for pervious concrete? While there can be a great deal of variablility between materials in market areas, the normal range is 500 - 200+ inches per hour permeability. This would seem to equate much closer to zero than to 0.85. Is there testing data that can be required? ASTM C 1707 is a permeability test for pervious concrete used to determine when maintenance is required.

Amy Rider

Sustainability Manager

KEMA Services

LEEDuser Basic Member

110 thumbs up

Tue, 05/29/2012 - 16:53

Hi Brian, 0.85 is the runoff coeffecient for brick pavement listed in the reference guide. For most products I assume that testing data isn't required, but if you are using something that greatly exceeds the permeability expectations of similar products you may wish to provide supporting documentation.