Pony Walls are the wood walls that are made with 2×4, 2×6 studs instead of using more block to complete the crawl space wall. Builders state that it takes $1500 their cost to add each additional block row as apposed to a PONY WALL costs 1/3 that. So builders cut costs and put in place pony walls. Trouble with pony walls is that they don’t come insulated in a standard foundation vented crawl space. Alot of moisture is wicked in because it has no insulation from the outside just the exterior covering…hardy plank…etc. So they leak energy and moisture more than a block wall wood. Cement blocks are hollow to hold air and air is natures best insulator. The more air a substance can hold the better the insulation value (R-Value)
A Tennessee Valley Authority study based on radiant barriers used in the summer found that
xx-a radiant barrier combined with an R-11 insulation has the same affect as an R-19 insulation alone.
xx–a radiant barrier combined with an R-19 insulation has the same affect as an R-30 insulation alone.
The Florida Solar Energy Center specialist Philip Fairey found that a radiant barrier combined with an R-19 insulation produced a LOWER peak energy demand than an R-30 insulation alone. (edit)