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Scott Caron offers advice on how to keep your home energy-efficient when using recessed lights

Question:

The recessed lights in my house are accessible from the attic, but there’s no insulation around them because it says on the fixtures that they need to vent the heat generated by incandescent bulbs. If I replace those bulbs with LEDs, will that reduce the heat enough so I can insulate around the existing lighting cans?
T. J. Guinta, Patchogue, NY

Answer:

While LEDs run much cooler than incandescents, their electronic components and external heat sinks do get quite hot; you would still need to keep the insulation away from your fixtures. And that leaves you with some serious problems. Those fixtures allow huge amounts of warm air—not only from the bulbs but from all over your house—to vent into your attic, which jacks up your heating bill, creates drafts, and contributes to the formation of ice dams after a snowfall. Also, every vent hole in your ceiling reduces its fire rating. Plugging the holes should be your first priority.

You could hire an electrician to replace each fixture with a sealed one rated for insulation contact (IC). But here’s another solution, which you can do yourself: Go to a home center and buy a fire-rated recessed light cover, like the ones made by Tenmat, for every fixture. Also, pick up a tube or two of firestop sealant, such as 3M’s Fire Barrier.

Up in the attic, clean the ceiling surface around each fixture, slit the cover to accommodate the electrical cable, and place the cover over the fixture. Apply the sealant around the cable and along the edge of the cover where it rests on the ceiling. Now it will be safe to heap insulation onto that spot.

I do recommend that you replace your bulbs with LEDs because they’re so energy-efficient, but make sure they’re rated for use in fully enclosed fixtures. If not, the heat buildup will shorten their lifespan significantly. For this application, I’m a big fan of the Halo recessed-retrofit LED downlight. It can withstand the heat inside a sealed IC fixture, comes in a warm 2700K color temperature, and is dimmable.


Scott Caron, a licensed master electrician and the owner of Caron Electric in Lexington, Mass., appears regularly on TV episodes of Ask This Old House.

from Jan/Feb 2016