Some federal tax credits from some energy-efficient home improvements and other energy saving measures have been extended.

But do you know which credits are available?

A number of websites offer varied and detailed information about the energy-efficient tax credits available to homeowners and builders.

Here is a sampling of sites:

• Air-Conditioning, Heating and Refrigeration Institute: spotlights specific federal tax credit amounts for changes made to residential HVAC, water heaters, home gas and oil, and more.

• Alliance to Save Energy: offers background and details on energy-efficient tax credits for 2012.

• Energy Star: Click on "Tax Credits for Energy Efficiency" near the bottom of the page to learn about different tax credits available for consumers.

• Saving2Invest: presents overview of home-energy tax credits extended into 2013.

• U.S. Department of Energy: provides several energy saving tax credits for various programs under the "Savings" section.