CFL lighting is difficult to pin down on a light scheme because of the manner the light is dispersed(as hinted at in michaels response.) Using WPG is also not a good way to judge lighting, since watts is purely matter of input not a matter of output. With more efficient lighting the input of 2.5 W/g is often entering into high light territory, with low efficiency lighting it is at the upper range of low light. CFLs are particularly complex because the geometrics of the bulbs affect the light quality and the orientation varies significantly from one manufacturer/bulb specification to another. So long as you plan on using CFLs it may be beneficial to find a bulb that you find aesthetically pleasing and then find where on the light intensity spectrum it falls and adjust your planning accordingly.