Insulation, Radiant and Vapor Barriers - crawl space

i have a 3 foot high crawl space under an old porch that was made into part of the house...floor space above this crawl space gets cold in the winter.the space consists of concrete block and a concrete floor with 1 vent on the side.what is the best insulation to use and where should i apply it.
should i just put insulation on the floor joist or cover the concrete block also.i will not disturb the vent cause i understand the area needs fresh air.there is no pipes of any kind or electric in this crawl spae....thanks for any help....

p.s. is it alright to use spray foam to create a good seal where the sill meets the foundation also...thanks again

Insulate between the joists with fiberglass. Doing this, you are creating an unconditioned space in crawl space. The lack of electrical makes it much easier and you don't have to worry about sealing the sill at the foundation.

What kind of climate do you have? - temperature, moisture, seasons, etc.

Dick

thanks cm for the reply..im in new york city area....cold winter and hot summer.so i will insulate the floor joist.now just to find wide isulation.house was built in the 20s and they didnt belive in 16 on center back then. :mad: ......also i figure on leaving the foil side on the insulation down facing the ground....again thanks for your help

Unless you're in an incredibly humid area, face the vapor barrier (foil, kraft paper, etc) towards the conditioned space.