The most economical without a doubt is consolidation.

You can spend less building 3 schools now or you can spend more refurbishing 6 schools and then in 10-15 years spend that again on the stuff that didn't get fixed this time around so then your at double the cost of 3 new schools that if done right won't need anything for 20 years and then it will pale in comparison to what it would have been to not consolidate.

There is noone with more school pride than me, GO BLUE KNIGHTS, but I am all for consolidation since it is what is the most logical and economical answer.