Our project are factory, the ventilation system use exhaust fans combined with louvre / open door to tranfer outside air direct from outside.
To monitor, we consider that is natural ventilation case so we suggest owner/MEP designer install CO2 sensor at between 3 and 6 feet above the floor combined with audible alarm when CO2 concentration exceeds the setpoint by more than 10%.
Recently, in our projects, LEED Reviewers don't approve CO2 monitor, they require exhaust fans greater than 1000 CFM (1700CMH) must be provided with monitoring devices.
It is correct?
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Kelsey Wotila
Foresight Management6 thumbs up
April 12, 2023 - 12:23 pm
Has anyone come across an answer to this? Is an exhaust fan with outdoor air intake louver considered mechanical or natural ventilation?
Candice Rogers
PresidentPaladin, Inc
21 thumbs up
April 12, 2023 - 12:34 pm
Since it requires a fan to draw ventilation air, it is mechanically ventilated. Natural ventilation would only rely on passive strategies - such as convection induced from process heat.
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
495 thumbs up
April 12, 2023 - 12:47 pm
I agree with Candice.
When electricity is needed for ventilation it is no longer "natural".
Kelsey Wotila
Foresight Management6 thumbs up
April 13, 2023 - 8:14 am
Thanks, Dave and Candice. Saw some posts that seemed to hint otherwise and got confused.
Afogreen Build
www.afogreenbuild.comGreen Building Consultant
219 thumbs up
July 25, 2023 - 5:36 am
Hi Kelsey,
Yes, agree with Candice and Dave,
It can be mechanical ventilation because it has fan to draw air. As define in ASHRAE STANDARD 62.2-2016, natural ventilation is define as ventilation occurring as a result of only natural forces, such as wind pressure or differences in air density, through intentional openings such as open windows and doors.
While, mechanical ventilation is the active process of supplying air to or removing air from an indoor space by powered equipment such as motor-driven fans and blowers.
Best regard – Afogreen Build Team
Afogreen Build
www.afogreenbuild.comGreen Building Consultant
219 thumbs up
July 25, 2023 - 5:36 am
Hi Kelsey,
Yes, agree with Candice and Dave,
It can be mechanical ventilation because it has fan to draw air. As define in ASHRAE STANDARD 62.2-2016, natural ventilation is define as ventilation occurring as a result of only natural forces, such as wind pressure or differences in air density, through intentional openings such as open windows and doors.
While, mechanical ventilation is the active process of supplying air to or removing air from an indoor space by powered equipment such as motor-driven fans and blowers.
Best regard – Afogreen Build Team