This much is undisputed: During the past three years, the federal government has phased in regulations requiring that 40- to 100-watt standard incandescent bulbs use 30% less energy to meet efficiency standards.

The old bulbs can be found in stores while supplies last, and it’s still legal to light ’em if you’ve got ’em, but manufacturers have shifted production to a host of new products that meet and often greatly exceed the new standards.

The main reason for the shift is waste. Only 10% of the energy that travels into a traditional incandescent bulb ends up as light. The rest goes out as heat, which may not be so bad during the colder months, but at this time of year you’re actually adding to your cooling costs.

Used appropriately, the new bulbs use less energy and last a lot longer. All of this means lower energy bills, less time spent balancing on ladders, and maybe the eventual end of light-bulb-changing jokes (though we hope it doesn’t come to that).

The most widely used of the new bulbs has been the compact fluorescent (or CFL). Available almost anywhere and with a price that’s still fairly modest (when taking into account the bulb’s energy rating and lifespan), today’s compact fluorescents have a lot going for them. They use less than a quarter of the energy of traditional incandescents, and recent entrepreneurship has resulted in lots of new choices in CFL design, lighting quality, and even instant-on capability. So if it’s been awhile, why not give them another try? You can get the same brightness you have now by forgetting about watts and checking the number of lumens listed on your old bulb; look for a CFL with the same amount.

Another concern has been the mercury content of CFLs, but even that is dropping as both entrepreneurs and established lighting manufacturers look for a competitive edge.  Taking this into account, an unbroken and properly recycled CFL still has a smaller mercury footprint than one of the old incandescents. Major retailers like Lowe’s, Home Depot, IKEA, and Ace Hardware offer their own CFL recycling programs, or you may be able to drop them off at your local co-op office. Check with your Energy Advisor.

One quick warning about CFLs, however: If they seem to be burning out more quickly than they’re supposed to, it may not be your imagination. That lifespan rating on the package is based on 3-hour on/off cycles, since turning one of these bulbs on and off eventually wears out its ballast. (That’s the device in the base of the bulb that delivers the juice.) So when you leave a room, think about how long you’ll really be away. It might actually be better to leave the light on for those few minutes.

We don’t want to overwhelm you with all the choices out there, because one of the things that most people seem to miss about the old incandescent bulbs is their simplicity. You had a soft white for inside, yellow for the front porch, and black for basement disco parties.

But we’ll mention just two more, because those of you who aren’t quite on board with CFLs may find something you like better.

First, there are hybrid halogen bulbs, which incorporate a halogen gas into a more traditional incandescent design to provide a closer match to traditional lighting. They turn on fast, and some are shaped remarkably like the light bulbs you remember. They do get quite hot, though, so if you go this route, make sure to take the proper precautions when changing or working near them. And though they meet the new standards, they’re not as efficient as other non-incandescents, so your savings may be less.

New LED bulbs are coming on strong, too. Like CFLs, they look a bit different from the bulbs of yore, but they outperform every other type in terms of energy use and longevity, and they’re ideal for situations requiring adjustable brightness. They light as quickly as a traditional bulb, and there’s no mercury to worry about, though like CFLs they require more careful handling and recycling, due to the presence of potentially dangerous substances such as lead and arsenic. Unless you’re breaking them on purpose and licking up the pieces, you should be okay.

Whatever bulb you end up choosing, you might want to avoid getting too attached to it. While all the bulbs we’ve discussed have made great strides in value, efficiency, and quality, there’s room for improvement with each of them.

The perfect light bulb may not exist today. But we’ll all know it when we see by it.