Title 24 Ventilation
Title 24 Ventilation
(OP)
Can anyone explain why the 2007 California Energy Code requires a mechanical system "capable" of providing an outdoor air rate no less than the larger of a) that prescribed by table 121-A or b) 15 cfm/person, yet the 2007 California Mechanical Code refers to ASHRAE 62.1?
The way it reads it sounds almost as though the system is required to supply air per ASHRAE 62.1, though it must be "capable" of supplying 15 cfm/person (more OA).
The size of a system capable of 15 cfm/person on a design day compared to 5 cfm/person + 0.06 cfm/sqft can be significantly different. In my case I am finding a tonnage around 20-25% more by using 15 cfm/person. Any comments? Thanks.
The way it reads it sounds almost as though the system is required to supply air per ASHRAE 62.1, though it must be "capable" of supplying 15 cfm/person (more OA).
The size of a system capable of 15 cfm/person on a design day compared to 5 cfm/person + 0.06 cfm/sqft can be significantly different. In my case I am finding a tonnage around 20-25% more by using 15 cfm/person. Any comments? Thanks.





RE: Title 24 Ventilation
Your local building official will have the final say so on the matter, pose your question to him/her and let all of us know the outcome.
RE: Title 24 Ventilation
RE: Title 24 Ventilation
In my experience, utilizing 62.1, I think the lowest result I've had on a VAV system is 13.5 cfm/person. This does not mean that is what I expect your answer to be, but just make sure you understand the procedure.
The main mistake I've seen is ignoring the minimum zone cfm conditions. Think about a space when there is no skin load, little or no lighting load, but is fully occupied. That is the condition that must be analyzed if the critical zone (think meeting room or assembly space when a presentation is being given.) I believe the 62.1 User Manual gives a good description of this.
RE: Title 24 Ventilation