Trini,
When you say concrete blocks what is
the insulation going to be? Standard concrete blocks have about a
zero insulation factor.
Have you looked at AAC (autoclaved
aerated concrete) block? I would highly recommend that you do.
AAC block has extremely good insulation
qualities and is relatively inexpensive to construct.
Depending on the part of the country
you are in there are several AAC manufacturing plants around the
country.
You can see what I have learned at:
http://www.greenearthstructures.com/aac.html
Good Luck!