http://www.energystar.gov/index.cfm?c=roof_prods.pr_roof_faqs#4

I believe the Energy Star department has suggested roofing materials. They do have a list of Energy Star approved roofing materials. Many of these are Metal http://www.energystar.gov/ia/products/prod_lists/roof_prods_prod_list.pdf

it may be a good idea to find a Metal roof from that list.

Roof Products Key Product Criteria http://www.energystar.gov/index.cfm?c=roof_prods.pr_crit_roof_products

there is a site matplex.com
it has roofing details and pricing on it.

Hi elvisfitch, Pensacola's roofing will help you with all of your roofing needs and offer all kind of roofing solutions for very reasonable rate. It is the best choice for you to replace your existing older or poorly functioning roofs with the most efficient reflective roof available in order to reduce energy use associated with cooling.

Cool Roofs | Reflective Roof

Well anytime you need roofing advice it is best to consult with a professional. Much more information needs to be obtained to accurately answer your question. What type of roof system do your currently have? Is your roof steep or low-slope? What is your budget? There may be a better option for you.