CFL question quick

Here's what I was looking for, it was in the Fluorescent - linear, circular etc one.

While it is often not possible to select lamp orientation, compact fluorescents work most efficiently when the lamp is oriented downwards, with the base up. This is because the efficiency of the bulb depends on the temperature of the coldest part of the lamp, which is the end furthest away from the ballast. Since heat rises, a base-up lamp will be coolest at the bottom, producing the greatest amount of light. Keep the lamp orientation in mind when comparing light output, which is rated for base-up operation