Warehouse Ventilation

[globe trekker]

Greetings to you all again!

I am seeking assistance in a new Warehouse addition project.

Here's the specifics: New Warehouse addition will be 19,970 sq. ft. NET (interior),

21,150 sq. ft. GROSS (exterior), ..all S-1 occupancy group ( automotive accessories),

..bldg. height (at the ridge) will be 19 ft.

The plans indicate 2 - 4 ft. x 4 ft. mechanical ventilation fans installed on one end

only of the bldg. No heating or cooling of this warehouse space will be provided,

only the ventilation fans.

I am trying to determine if these 2 ventilation fans meet the minimum requirements

for ventilating this addition. No other means to ventilate are indicated. I am

unsure of the formula / math to use to determine compliancy.

Can someone who is familiar with this type of application please assist. Your

formulas would be nice to see & review!

We are using the 2006 Edition of the I-codes.

Thanks!

.

 

[steveray]

See IMC 403.3......and get the specs on the fans....

Storage

—

Repair garages, enclosed

parking garagesd

—

1.5 cfm/ft2

Warehouses

—

1.5 cfm/ft2

 

[globe trekker]

Thanks "steveray" for the input! My 2006 IMC, Table 403.3 only requires 0.50 cfm/ft.2 for

Warehouses.

.

 

[klarenbeek]

Check your table again. Its only .05 CFM/ ft.2 for warehouses. That will make a big difference.

 

[steveray]

Hunh...it cut and pasted funny out of public e codes....

 

[globe trekker]

klarenbeek,

You are correct! My bad for the typo mistake.

Can you enlighten me (and others) some more on the formulas I should be using?

Essentially, I have a total of 32 sq. ft. of openings for exhausting only. I do not

see any intake openings elsewhere on the project plans.

Thanks!

FWIW, with the info I posted in the OP, I have 19 ft. ridge height x 19,700 sq. ft.

of floor area = 374,300.0 cu. ft. to ventilate.

Please help a mathematically challenged individual!

.

 

[steveray]

9850 cfm = 19700x0.5

 

[klarenbeek]

All it is is 19,700 (floor area sq. ft) X .05 = 985 cfm exhaust. A 1000 cfm fan should be able to handle it (on basic projects like this we'll go off the nameplate rating), and then gravity makeup air with a backdraft damper should be fine. Code only requires ventilation based on square footage, not cubic. If there are enough overhead door openings to the outside to equal 4% of floor area to provide natural ventilation, mechanical ventilation is not even required.

 

[globe trekker]

klarenbeek,

Thanks for the follow-up! This 19,700 sq. ft. addition will be attached to an existing area

of the warehouse, by one roll-up door, and having 2 exterior egress doors ONLY.

The RDP is showing 2 - 4' x 4' louvered exhaust openings, ..side by side essentially.

No other doors or openings are indicated on the plans!

.

 

[Dr. J]

A couple of concerns:

No other doors or openings are indicated on the plans!

See IMC 501.3: "...adequate make-up air consisting of supply air, transfer air or outdoor air shall be provided to satisfy the deficiency. The calculated building infiltration rate shall not be utilized to satisfy the requirements of this section."

Need a positive means of make-up air. Just a louver would do it. IECC 502.4.4. requires a damper at both the exhaust and outside air. A BDD won't work to prevent infiltration on the outside air inlet because the air WANTS to go in. Damper must be motorized. BDD can work on exhaust because it will allow air out, but not in.

The 0.05 cfm/sf is for outside air, not exhaust. And further, per IMC 403.1 this outside air must be delivered to within 6' of the floor. Yes, exhaust will induce outside air into the building, but the designer needs to show that the outside air makes it to within 6' of the floor. Roof mounted exhaust and roof mounted intake won't cut it. This can be solved by having the designer determine a ventilation effectiveness (see ASHRAE 62 or 2009 IMC TABLE 403.3.1.2), and increasing the outside air (exhaust) accordingly.

No heating or cooling? Freeze protection? Note the system must be on whenever occupied (IMC 401.3). Either operating all the time during business hours, or cycled via an occupancy sensor (probably a whole bunch of occupancy sensors to "see" around all the wares housed there). Manual switch does not cut it.