Ventilation Requirements for Repair Garage

[ChrisConley]

Hello all,

I have a repair garage that requires ventilation to meet code. The code requirements for a repair garage are 1.5 cfm/ft2 as per ASHRAE 62.

This works out to 11,000 cfm of OA and a pretty large make-up air handler for the size of the building (around 7300 ft2)

ASHRAE 62, and the Canadian National Building Code, do allow for natural ventilation of spaces where the occupancy is less than one person per 430 ft2, which is the case for the repair garage in question.

Again, ASHRAE 62 states that if operable openings with a total area of or 4% of the floor space are provide the space can be considered naturally ventilated (I'm summarizing). The large overhead door will have an area of over 8% of the floor space so we should have no problems with that requirement.

The ASHRAE Standard's main concern seems to be controlling humidity (which is not a concern where I am) and not dealing with cold temperatures.

My question is (sorry it took so long to get here) is that although it seems to meet code, I'm uncomfortable providing natural ventilation only for a repair garage. I know that during winter (-40deg) no mechanic will open the garage door to ensure their space is well ventilated.

Has anyone else run into this situation? What has anyone else done to ventilate a repair garage?

 

[friartuck]

In mild climates, nat vent via openable doors is normal approach....however in 'freeze yer nuts weather' a different approach is needed.

LPG vehicles now require extra vigilence due to the gases high density which can cause a dangerous atmosphere. Low level vent is recommended (As well as high level)

Motorised louvres might be used here.

Floor mounted gas fired heaters are a no no again due to low lying gas vapours so high level radiant are best option or even underfloor htg.

Go to HSE in uk for assistanve in garage ventilation design (Free advice on web site)

Vent rate needs to be high, usually works out at least 3ac/hr though figures are available in CIBSE and ASHRAE guides based on engine size etc.



Friar Tuck of Sherwood

 

[imok2]

this may be of some help:

http://www.gov.on.ca/LAB/english/hs/eds/eds5-07_garage.html

 

[ChrisConley]

Very useful information all, thanks for everything. I don't know where you find all your websites imok, but I'm glad that you do. If anyone else stumbles across this thread I'd also like to recommend

http://www.ngvs.com

The above is the website of a company called National Garage Ventilation Systems. Very useful information.

**If you are not part of the solution, then you are part of the precipitate.**

 

[MarauderX]

We made a more complicated control spec. We have an underfloor exhaust system that provides a flexible connection to be connected to the exhaust pipe of the vehicle. When the door is open this system and the make-up air system do not run, but when the door is shut the system fires up after 5 minutes. We're still waiting for it to be 'value-engineered' out eventhough the owner is the one who wanted the underslab exhaust.