Crawl Space Ventilation
Crawl Space Ventilation
(OP)
I am a mechanical engineer working on HVAC renovation of a 50 year-old private (6-12 grade) school. Part of the duct work and most of the Hot/Chilled water piping is in the crawl space. The owner wants to ventilate the crawl space. One, is this part of an architect's job to calculate the ventilation requirement or the mechanical engineer. Two, what is the process and what are the code requirements?





RE: Crawl Space Ventilation
2) Code requirements for ventilation are typically based on occupancy (reducing CO2) in the space or they are based on limiting some other contaminant concentration (like noxious fumes, flammable gases, etc.). However, for your situation I believe the code requirement is based on moisture concerns in the crawl space. I believe you can check your building code for the requirement. If your local building code references the International Building Code, then look at Chapter 12 Interior Environment.
Justin K, P.E.
http://www.engproguides.com
RE: Crawl Space Ventilation
RE: Crawl Space Ventilation
RE: Crawl Space Ventilation
Adhering to the international code (IBC, IMC) I believe the crawl space has to be ventilated if it is unconditioned. As mentioned by jkauwale, if you are only ventilating for humidity and not any bad stuff (radon or what have you) the requirements are outlined in IBC and IMC. If these are your governing codes...
If naturally ventilated the architect would typically take care of it.
If mechanically ventilated the mechanical engineer would take care of it. The rate and RH limit is outlined in Chapter 4 of the IMC.
I imagine other codes (uniform) are similar.
Watch your freeze conditions if the fan is running, you have water lines in the crawl and the outside air is cold...
RE: Crawl Space Ventilation
Unvented crawlspaces are a problem waiting to happen, and it should have had natural ventilation when it was originally constructed, regardless of location.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Crawl Space Ventilation
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Crawl Space Ventilation
RE: Crawl Space Ventilation
RE: Crawl Space Ventilation
knowledge is power
RE: Crawl Space Ventilation
Also, anyone knows any OSHA related rules? I think OSHA asks for lighting of crawl spaces.
RE: Crawl Space Ventilation
It sounds like it already has natural ventilation.
If your relative humidities are still above 60% then you need to look at the crawlspace floor for rising damp.
Adding a ventilation fan in a situation like that is curing the symptoms not solving the problem.
B.E.
The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor
RE: Crawl Space Ventilation
So make it yours. your title carries a "V" in HVAC engineer.
RE: Crawl Space Ventilation
One way to do this would be to install a inline exhaust fans at the existing vents on one side of the building (closest to power source and entry to space for service), and draw make-up air from the opposite side. This worked for me in WI, they had mold in the crawl space and they also had vents.
This is Dallas so there are no issues with freezing pipes in the crawl space right?