Recomended air changes in air conditioned process area.

[chemuss]

Hi,

Can anyone help me or point me in the right direction in regards to air change requirements for refrigerated process areas. I have a 30m L x 30m W x 4.5m H processing room with about 40 workers. I need to find out how many air changes required for this space with this many occupants. The room runs at +8 degrees celsius and has three 3m L x3m H rapid roller doors. The workers are in there worst case scenario 16 hours being a double shift. Any help would be appreciated. Thanks.

[Magoo]

Hi.
your local building code requirements will require something along the lines of 10 litres per minute fresh air per person in an enclosed work space area, being refrigerated space better to have a positive air supply and spill air to outside along those lines, a few pa pressurization will be good. Pressurization will eliminate bugs and flies, and fowl/faul air influx. Can be a huge part of heat load though so take into account with heat loads.

[chemuss]

Thanks,

I will check out the 10 litres per minute, I thought it might have been 10 litres per secound but that sounds a bit excessive.

[r.bartlett]

10 l/s in the uk.

[Magoo]

Hi r.bartlett
I think you are correct, an international standard requirement, adds huge loads to cooling system anyway.

[r.bartlett]

Hi r.bartlett
I think you are correct, an international standard requirement, adds huge loads to cooling system anyway.

Use HRV and the effect is neutral.

[hookster]

General Ventilation in the Workplace regulation 6 states that the fresh air supply rate to your workplace should not normally fall below 5 to 8 litres per second, per occupant.

CIBSE is 8 litres per second

10 litres per second is usually specified by recommendation for office environments

The minimum standards are of course affected by door opening rates, pollutants, forklifts etc etc
I am with Magoo design with <5 Pa positive air pressure with full openings and you will easily exceed requirements with an excellent impact on your energy operating conditions

Or you can look at monitoring work space conditions and boost ventilation as and when required.

HRV (heat recovery ventilation) can reduce energy impact but as to being neutral I have to disagree.

[NewmanRef]

HRV (heat recovery ventilation) can reduce energy impact but as to being neutral I have to disagree.[/QUOTE]

HRV is usually about 70% efficient.

[install monkey]

if its fitted in aus then its going to increase the cooling load in summer- 40 deg outside dumped in to a conditioned space but also give free cooling in winter

[chemuss]

Good feed back guys. I will gain free cooling in the cooler months. Instead of sucking air from directly outside I will look at sucking air from an air conditioned corrodor which backs onto processing coolroom. I found a ebm ec fan m/n : K3G250-AV29-B2 that might do the job. It moves about 2000 cubic meters/hr of air. Maybe a bit over sized but occupants fluctuate now and then.