Actually, the amount and specific wavelengths of light blocked by Low-E
coatings depends on the
chemistry of the coating, it's thickness, and to a lesser degree, which
surface it coated.

Most of the modern spudder coat Low E is on the number two surface and is made
up of two layers of silver with several layers of oxides to make it possible to
see through the glass.

Hard coat Low E glass used tin based coatings that were fused when the float
glass was made. These coatings are typically on the number three surface. They
do not perform as well as the spudder coated products, have an oil slick
appearance and in most cases do not meet the new Energy Star requirements for
shading co-efficient or solar heat gain. They typically only block about 55% of
the UV.