Is there a low energy light bulb for every type of fitting?
Yes. Lamps are now much smaller than previous CFL ones, and come in very similar sizes and shapes to incandescent lamps. They come in all bayonet and screw fittings now. Where fittings are really small, halogen ‘look-alike’ lamps are available, although these do not offer the same energy savings. Dimmable versions are also available.