An earlier comment said that, "LEED Interpretation #10098 seems to be saying that, if your entry system is at the exterior &/or less than 10 feet long, you will need to write a darned good justification explaining how your alternative approach is every bit as good as (and better than) the prescribed 10-foot indoor system".
What about providing half of the walk-off on the exterior through a grate or scored paving for larger particulates that you never want entering the building, and the other half as a finishing area/mat to clean the particulates that were not already taken off just outside the entrance? This method is advocated by the Living Building Challenge and seems to make sense from both a maintenance and cleanliness point of view.
If provided with documentation of this half-exterior / half-interior walk-off system, would this justify the alternative approach for the #10098 exception?
Michelle Halle Stern
Senior Sustainability ConsultantGreenwood Consulting Group
120 thumbs up
August 14, 2015 - 4:05 pm
It's worth a try with plenty of support including precedent with LBC. The worst that can happen is the reviewers could reject it. It sounds like you don't plan to put a 10' mat inside regardless.
Aaron Levine
Architectural DesignerSagan Piechota Architecture
1 thumbs up
August 14, 2015 - 5:32 pm
Thanks for the reply, Michelle. Do you know of projects with alternative walk-off systems that have been granted this exception for reference?
Michelle Halle Stern
Senior Sustainability ConsultantGreenwood Consulting Group
120 thumbs up
August 14, 2015 - 7:27 pm
I am not aware of any specific projects. Document any research that shows the benefit of a grate outside versus having a 10' entryway on the inside. Are you sure you can't install a 10' rollout mat on the inside and contract for weekly cleaning? Or a combination of grate and rollout mat indoors, I would is acceptable.
Aaron Levine
Architectural DesignerSagan Piechota Architecture
1 thumbs up
August 17, 2015 - 6:36 pm
Yeah, it's not really an option for our project.
On a related note, do you have any guidance on how scored stone can act as a substitute for grating as a part of the walk-of distance? We have stone at our entry way and rather than inserting a grate would prefer to keep our material the same. Thanks again!
Michelle Halle Stern
Senior Sustainability ConsultantGreenwood Consulting Group
120 thumbs up
August 18, 2015 - 11:39 am
Go back to the credit intent, which is to source control fo indoor contaminants to prevent occupant exposure. 80% of contaminants, specifically particulates, come into a building from feet upon entry. You are clearly attempting something that departs significantly from the credit requirements. In this case I recommend you design the best possible solution that addresses the intent, fully justify how your solution meets the credit intent, and wait to see what the reviewers say. This argument will be much stronger if you find research, examples, or expert opions. Focus less on whether what you do will be acceptable to reviewers, and more on the best solution to protect building occupants.
Aaron Levine
Architectural DesignerSagan Piechota Architecture
1 thumbs up
August 18, 2015 - 12:49 pm
Thanks for your comments! We are not attempting to depart from the credit requirements as they relate to keeping dirt out of a building and building air, which is the intent.
We are simply trying to understand the logic behind the method for achieving this result, as we have found varied recommendations for walk-off surfaces that deviate from LEED, such as those recommended by the Living Building Challenge (LBC) under their "Health and Happiness" petal. It's helpful to know what is/is not possible before bringing our recommendations to the client.
Thanks again, Michelle!
Jon Clifford
LEED-AP BD+CGREENSQUARE
LEEDuser Expert
326 thumbs up
August 20, 2015 - 6:24 am
Why not?
To use an alternate compliance path, LEEDonline requires a narrative to justify the approach. The first step to ANY such narrative should be to address WHY the prescribed approach is “not an option.” Next, describe the alternative used, and finally, provide “justification that this path meets the credit intent and requirements.” As Michelle suggests, provide research, empirical data, or other evidence comparing your strategy to the prescribed approach.
I have not sought this path, but I have used the outline above to draft “darned good” justifications for other credits.
If you choose to pursue an alternative approach, you may wish to submit a formal inquiry describing your proposal prior to implementation to confirm that it is acceptable.
Jon Clifford
LEED-AP BD+CGREENSQUARE
LEEDuser Expert
326 thumbs up
August 19, 2015 - 10:19 pm
To best understand LI#10098, read it in its entirety, as well as the related IEQc5 Rulings that it supersedes: http://www.usgbc.org/leed-interpretations?keys=10098. Recognize that LI#10098 applies only under extraordinary circumstances such as existing conditions that restrict the available space. (See the July 23 post farther down this page.) If your project has constraints that preclude the required mat, these may be your “WHY.”
The link above includes several older, more flexible rulings that once allowed configurations similar to what you describe. These strategies may still be acceptable if you first meet the “physical impediments” criteria in LI#10098.
Also at the link above, LI#6093 is an ancient Ruling, not applicable to LEED-2009, but it describes three criteria for evaluating entry systems that may still be relevant when comparing strategies. (Beware: Parts of this Ruling are seriously outdated.) LEEDv4 also emphasizes cleanability.