Home Energy readers are collecting clues to the mysterious stains found more and more often in homes. It turns out that many black, sooty stains are the result of deteriorating insulation in the HVAC system.

Illuminating the dark and mysterious corners of a three-centuries-old New England landmark with modern, energy-efficient lighting required a careful hand, a vintage design, and an unobtrusive approach.

Makers of ozone-generating indoor air cleaners want consumers to think they can increase health and safety in the home. John Manuel filters through the PR haze and shows that these units have no proven benefits and may even be harmful to occupants.

Utility Web sites now allow residential customers to review their annual energy costs and get energy-saving tips--right from their computers.