Color Absorption

I think you're confusing light in the visible spectrum with higher energy wavelength's that are not in the visible spectrum...surfaces that reflect visible light need not be good reflectors in another wavelength....people generally settle for white, but if you wanted to take it to the next level you might go with a mirror, or polished aluminum....I have used foil backed material for lining attic roofs that work well at reflecting heat....so possibly a multi-level approach would work best....

"The UV region covers the wavelength range 100-400 nm and is divided into three bands:

• UVA (315-400 nm)
• UVB (280-315 nm)
• UVC (100-280 nm).

As sunlight passes through the atmosphere, all UVC and approximately 90% of UVB radiation is absorbed by ozone, water vapour, oxygen and carbon dioxide. UVA radiation is less affected by the atmosphere. Therefore, the UV radiation reaching the Earth's surface is largely composed of UVA with a small UVB component."

http://www.who.int/uv/uv_and_health/en/

Seem like everything has its distinct purpose, i thought about colors before only beautifies the environment, more like for visuals and for self defense, but only to find out it is a constituent to the mystery along with geometries. Cool.