Hi eQuesters!

I am modeling a Laboratory building with Fume Hoods (Climate zone 4A).

Per ASHRAE 90.1-2007 Appx.G 3.1.2.10, the baseline laboratory AHUs should
be installed with Energy Recovery (SA>2400L/s & OA 70%).
However, there are 'Exceptions' and one of which says as follow:

*h. Systems serving laboratories wish exhaust rates of 2400 l/s or greater.*

Does it really mean that the Baseline AHU is not required to have ERV if
the AHU has an exhaust rate(Not return) of 2400 l/s or greater??

I don't know the reason under that exception(h), but anyhow, that
will be beneficial for my proposed model which has ERV(sensible HX) for the
laboratory AHUs.

Any comment on this?

Thank you !!

Kim