Hi to all,
I am confused regarding the minimum indoor air quality calculation. In my case, I have one single zone system and several spaces with 100% outdoor air systems, the project is aiming for a 30% outdoor airflow improvement. In the minimum indoor air quality calculator there is a formula for calculating the breathing zone outdoor airflow (Rp*Pz+Ra*Az)*1.3 required. However, the definition of the breathing zone according to ASHRAE 62.1 is very clear: the region within an occupied space between planes 3 and 72 in. (75 and 1800 mm) above the floor and more than 2 ft (600 mm) from the walls or fixed air-conditioning equipment.
Is this applicable for single-zone and 100% outdoor air systems?
Could somebody clarify to me where I have to take this breathable zone into consideration in my calculations?
Thanks
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
November 13, 2023 - 1:46 pm
It does not make a difference to your calculations. OPnly the zone area and population are taken into account for the ventilation rate. Once you have that, you can apply effectiveness. For a single zone you won't have diversity or unused air going into your calc.
Julio Fernandez Amodia
5 thumbs up
November 13, 2023 - 3:49 pm
Hi Andrew,
Thank you for your response. So, when is required to take into account the breathable zone? Why ASHARE 62.1 is so specific if it is not to be considered in any of the calculations?
Thanks
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
November 13, 2023 - 4:02 pm
I think that there could be cases where your zone area may exclude portions that a person could not occupy the breathable zone.
Nagaraj Sankar
November 13, 2023 - 10:28 pm
Hi users,
1)One of our Production building project having fresh air supply with fresh air louver opposite to the exhaust fans which is present in the office spaces of the building how can account this in fresh air calculator.
2)And how can I account the fan power of exhaust either in fresh air fan power or exhaust fan power.
3) How can I justify this system will met the requirement of 30% fresh air supplied to an individual space.
4)And by what system I need to choose (Gross Floor Area - 1,50,000)
Please guide me anyone having experience on this , It brings me an another learning ,
Thanks in advance
Julio Fernandez Amodia
5 thumbs up
November 14, 2023 - 5:08 am
Hi Andrew,
Could you provide an example?
Thanks
Andrew Mitchell, P.E.
PrincipalMitchell Gulledge Engineering, Inc.
LEEDuser Expert
126 thumbs up
November 14, 2023 - 8:16 am
If you had a high density storage facility, you could make an argument that the population can be reduced by the area that is all storage and not occupiable. It's not a route I have taken, but I could see the argument being made.
Dave Hubka
Practice Leader - SustainabilityEUA
LEEDuser Expert
495 thumbs up
November 14, 2023 - 8:43 am
good idea Andrew!....unfortunately i tried a similar route with no success.
we had a factory with extremely large and permanent equipment. i tried to claim the floor area taken up by such equipment as "unoccupiable" and exclude it from the factory floor area in my vent calcs. GBCI did not allow this exclusion.