What are the differences of heat output between conventional incandescent bulbs and the new "green" bulbs?

These new "curly" bulbs use a small fraction of the energy that conventional bulbs use. Bulbs produce two products, light and heat. Most light fixtures indicate a maximum bulb wattage but that is determined by the maximum amount of heat that the fixture can safely withstand. I am looking for the results of a scientific study that compares the heat output of incandescent bulbs vs "green" curly bulbs. This will allow me to calculate the maximum wattage available from a fixture by simply changing the bulb type, instead of changing or adding fixtures, to get more lumens. It anyone knows of a UL study, that would be perfect.