Ventilation rate, person and area

[317069]

Hello,
1- a 1000sq.ft of office space with 4 occupants needs [(5*4)+(1000*0.06)]= 80 cfm of outdoor air.
2- a 2000sq.ft of office space with 4 occupants needs [(5*4)+(2000*0.06)]= 140 cfm of outdoor air.
both spaces have the same height, same everything except the area.
I think the air in the 1000sq.ft space has more CO2 concentration than the air in the 2000sq.ft space. What do you think?

 

[cdxx139]

Yes, but the 2000 sf room has more furniture and potential for off gassing as an example. Ashrae 62 is for all indoor air quality, not just CO2.

knowledge is power

 

[317069]

I agree but not 100%, even it is not necessary to have more furniture, the subject of the outdoor air is to handle gases like Co, CO2, NO2..etc. not dust, dust could be handled by a filters, for example when you use vacuum to clean your furniture, you don't use outdoor air.

 

[317069]

also for gases, should it be related to the volume or area, let say 10'x10'x10' will have the same volume of 20'x10'x5' but double area, that mean double outdoor air

 

[Drazen]

co2 measured in closed space is a figure relative to outdoor co2 concentration. it comes only from breathing species like humans.

 

[EnergyProfessional]

IMC take area and people into account to account for both off-gassing and CO2.
Are you sure about the number of occupants? 500 ft2 per person? Are they super CEOs or something?

IMC and ASHRAE also prescribes how many ft² per person you have to assume. This is to take into account potential changes, and avoid bad assumptions. Like in your case those may be people with a lot of visitors.