Air changes per hour

[subairg]

Hi,
How to calculate air changes per hour of room?. any standard values are there in ashare?

Thanks!!!
Subair.g

[B G Scott]

Yes there are recommendations, what is you particular application?
The air change rate is dependant on the type of application, ie. industrial, commercial, residential etc.

[Sandro Baptista]

...And it's not an exact science...far from that. It depends on of whom and how the room is used.

[Windy Allah]

Hi subairg,

This is a basic formula that I use for sizing up a room. I normally use it with conjunction with Heat load calc. (L x W x H x AR x 1000) = L/s
3600
AR for domestic 10 to 12 AR
for commercial 12 to 15 AR
for Evaporative 30 to 35 AR

[Sandro Baptista]

Hi subairg,

This is a basic formula that I use for sizing up a room. I normally use it with conjunction with Heat load calc. (L x W x H x AR x 1000) = L/s
3600
AR for domestic 10 to 12 AR
for commercial 12 to 15 AR
for Evaporative 30 to 35 AR

hmmm...for big cold rooms that is too much. That should be only valid to small rooms.

[sterl]

Refrigeration Load section of the ASHRAE Refrigeration Handbook goes through this in quite a bit of detail....Largely based on the method of Gosney & Olama.

In a very large, cold storage type building with minimal doors, low traffic good vapour barriers and stable sheathing: it will work out to less than one air change in 24-hours.

Some small walk ins and "baby" blast type freezers, it can be upward of 10 per hour...Overalll effect depends on building interior height compared to door height, pressure effects due to such things as ceiling ventilation, orientation of evaporators particularly on inside of a CSW and so on.