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I would add to David's answer:

• For ACH, around 1.0 ACH is what you're looking for (See this interesting article from Lstiburek at BSC). Maybe a bit more, but nothing extreme as long as it's passively ventilated. Anyway, it won't have a tremendous effect, as you'll see if you output the crawlspace's temperature. It does have an effect, but it's more on RH conditions in the crawlspace due to the moisture content of the air (more for condensation problems rather than energy) rather than temperature.
• As far as internal loads, think about whether you have ducts and/or heating/DHW piping in there, especially if uninsulated.

I would add to David's answer:

• For ACH, around 1.0 ACH is what you're looking for (See this interesting article from Lstiburek at BSC). at¹. Maybe a bit more, but nothing extreme as long as it's passively ventilated. Anyway, it won't have a tremendous effect, as you'll see if you output the crawlspace's temperature. It does have an effect, but it's more on RH conditions in the crawlspace due to the moisture content of the air (more for condensation problems rather than energy) rather than temperature.
• As far as internal loads, think about whether you have ducts and/or heating/DHW piping in there, especially if uninsulated.