Hi all,
We are working on a warehouse project which is implementing a strategy for supplying the outdoor air by using a roof exhaust unit and forcing the supply of OA through the intake louvers; so the outdoor airflow would be induced by the negative pressure generated by the extraction, but we are not sure if this strategy can comply with the Minimum Indoor Air Prerequisite and ASHRAE 62.1-2010:
Could this be considered an acceptable strategy (as long as we get the minimum OA rates per the VRP) under mechanical ventilation system?
If so, how can we keep compliance with filters and outdoor air monitoring requirements? Or could we use the exception under 6.2.1 Outdoor Air treatment:
Exception: Systems supplying air for enclosed parking
garages, warehouses, storage rooms, janitor’s closets,
trash rooms, recycling areas, shipping/receiving/distribution areas
Or would this need to be considered under a Natural Ventilation strategy?
Any insight is appreciated. Thank you,
Santiago Avila
Junior Sustainability EngineerMay 5, 2022 - 4:22 pm
Hello, can someone help me with this please?
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
540 thumbs up
May 7, 2022 - 8:24 am
What you have described is a compliant mechanical ventilation strategy.
Regarding the outdoor are monitoring requirements of the prereq:
If constant volume then balance outdoor air to design minimum, or higher, and install a current tranducer on the exhaust fan OR airflow switch OR similar monitoring device.
If variable volume then provide a direct airflow measuring device capable of measuring the minimum airflow rate. The device must measure the minimum airflow rate with an accuracy of +/-10% of the design minimum airflow rate. An alarm must indicate when the airflow rate varies by 15% or more from the airflow setpoint.
Please note that the reference guide language does not require an alarm on constant volume systems.
Hope this helps!
Santiago Avila
Junior Sustainability EngineerMay 11, 2022 - 1:19 pm
Thanks for your answer, it helps a lot! Do you know if this strategy needs to comply with filters requirements for OA intakes?
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
540 thumbs up
May 11, 2022 - 3:24 pm
EQp Minimum IAQ Performance does not include any filter requirements.
EQc Enhance IAQ Strategies include filter requirements. It is my guess that MERV 13 filters on outdoor air intakes would not meet the credit requirements since a louver is not considered "HVAC equipment". Design-side, I don't think they'd work due to the pressure drop. OA would most likely be pulled in from overhead doors, man doors, and leaks in the envelope OR cause a pressurization issue.
good luck!
Francesco Passerini
engineer90 thumbs up
May 11, 2022 - 5:06 pm
EQp Minimum IAQ Performance requires filter M6 if the project team is demonstrating compliance with ASHRAE 62.1 and if the building is in not attainment area.
There are intake vents where filters can be applied.
Regards
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
540 thumbs up
May 11, 2022 - 5:50 pm
Francesco, you are absolutely correct!
thank you for adding to this thread.
I would also agree that filters can be applied at the intake vents to demonstrate prereq compliance.
Santiago Avila
Junior Sustainability EngineerMay 17, 2022 - 12:45 pm
Thanks!