We're scraping bottom on my knowledge of construction practices. Other than falling off a tile roof, I've never build or specified one. I think the article refers to tile coatings, not the actual tile itself.
Googling for cool red tile coatings: Looks like you can get IR reflective roof tiles in any color EXCEPT red. Maybe they mean terra cotta which is kinda red and has the highest IR reflectivity? Oh wait, you can get the coating in cool red (also known as Thai Pepper):
Yep. That all makes sense. Looking at the definitions for SR and SRI, there are multiple factors (refection, absorption, emission, roof slope, etc) involved in calculating the indexes. Nothing is simple.
I found some detail on the difference between SR (solar reflectance) and SRI (solar reflectance index). (note the assumptions).
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