Much of the information I've read up until now has stated that "insulation" is the way to reduce temperature change - and thereby reduce our energy consumption. So three candidates were investigate for cost at Home Depot.
* Reflectix "Radiant Barrier" 500 sq.ft. roll
* Insulafoam 4'x8' panel
* Solarflex paint (data sheet) 287 sq.ft. coverage per 5 gallon bucket
Its worth noting that painting would likely have a lower labor cost, and painting reflects the a portion of the heat versus being a barrier to heat.
|product||cost/unit||cost per sq. ft.||cost for 5000 sq. ft.|
|Reflectix Radiant Barrier||$66/roll||$0.1320||$660.00|
|Solarflex roof paint||$70||$0.2438||$1,219.51|