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A smorgasbord of requirements
This credit requires compliance with a varied group of items that cumulatively help keep pollutants out of the indoor air. These requirements include self-closing doors on janitors' closets, MERVMinimum efficiency reporting value. 13 filtration on mechanical equipment, and entryway trackoff systems.
Compliance will require the coordination of team members—including the mechanical engineer, architect, plumbing engineer, and contractor—and also impact project design and operations. The basic requirements are:
- Permanent entryway walk-off systems at least 10 feet long (up from 6 feet in previous versions of LEED) at all regularly...
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14 Comments
MERV 13 filters on fan coil units
Numerous CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide responses and LEED Interpretations previously denied the credit where fan coil units recirculating room air for supplemental cooling in high load spaces were equipped with MERVMinimum efficiency reporting value. 8 filters and where the ventilation air was supplied directly to the space by central systems with MERV 13 filters. Language added to these responses now indicates that revised credit language for LEED 2009 removes the requirement to provide MERV 13 filters on return air. MERV 13 filtration is only required on outdoor air. Is there any reason to expect a credit application under v2.2 with fan coil units only recirculating room air and equipped with MERV 8 filters will be denied?
Fantastic question. Found another grey area in LEED. Do addenda for 2009 credits apply to credits in v2.2.
IMO you should be able to comply with the latest ruling in this case, because in this case the credits are very similar between 2009 and v2.2. Consider adding a narrative.
Can 10' requirement be met by a combination of mats?
Due to space constraints, our vestibules were not able to be a full 10' wide between our doors, thus the recessed walkoff mats aren't 10'. Does anyone see any issue with supplimenting the distance with a roll-off mat (properly maintained of course) laid out at the other side of the vestibule? The end result would be more than 10', but it would have a couple inch "break" as you passed through the door from the vestibule into the lobby.
Renee- that shouldn't be a problem at all- we have had several similar situations and a combined length has always been accepted.
IEQc5
What does the Average Pressure Differencial mean and where would I find that info on the plan set for this credit?
Thanks!
Look for a copy room or janitor's closet. You want to find the amount of air that is regularly exhausted from those rooms. If air is also supplied into the space you need to subtract that number to find the total exhaust.
An ASHRAE equation for Pressure (∆P) in PA is:
Q=165.5*A*√∆P
Here is an example scenario:
3 foot wide closed door with a 0.5" undercut
A=0.125 ft
∆P=5 (required for LEED)
Solve for Q (Air Flow in CFM)
Q=165.5*0.125*√5 = 46.3 CFM
In order to ensure this room has a negative 5 PA differential pressure to an adjacent space you need to have roughly 50 CFM total exhaust (Exhaust CFM - Supply CFM). Area of the room is irrelevant for this equation but for LEED and local building codes you may also need to ensure that you have at least 0.5 CFM/SF exhaust.
The door also needs to be self-closing to achieve this credit.
Walk-off mat size
The requirement for walk-off mats is vague in regards to size of mat required. I think they are typically 4'x6' or in that range, does the 10 foot requirement only apply to permanently installed entryway systems? Thanks.
Hi Will, the requirement seem very vague to me. If you're using a rollout mat, the 10-foot requirement still applies. If that weren't the case, that would be a major loophole in this credit.
Permanent entryway walk-off systems at least 10 feet long
Q #1: We are working on design of 10-story school in downtown of the major US city. Design calls for roof play yard. Do we need to apply 10 feet rule for re-entry doors leading to elevator lobby?
Q #2: Design of another urban school calls for roof garden - do we need permanent walk-off system rules apply to re-entry from the garden?
Yes- you should plan for 10' of walk-off system at the building entries from both of these exterior spaces. The idea is to contain particles, dust and dirt before they can get in the building and since you have the opportunity to pick up dirt and debris on the roofs, walk-off surface is required.
Receiving Room Doors
Our LEED-Schools project has a Receiving Room with a roll-up door and a man door. Are the entryway systems required at both the roll-up and the man door?
There is also a Receiving Office located within the Receiving Room. Will this room need to be physically separated from the Receiving Room via deck-to-deck partition or a gypsum board ceiling? Should a self-closing door be specified here?
Thank you!
We do not typically provide entryway systems at overhead doors- just man doors.
The receiving room does not need to be separated from the receiving office unless it meets the requirement of hazardous gas or chemical areas.
Courtyard Classrooms
All of my classrooms are entered directly off of a courtyard. So do I really need 10' of walk off mat per classroom? If so, I am thinking I will need to punt on this one. Just looking for some feedback - thanks.
The requirement is for "regularly used" entries to have the track-off mat; however that terms is not well defined. However, in this case it sounds like those entrances are regularly used and would be subject to the requirement.
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