Justin Brown has moved into a house with lots of recessed lighting fixtures, including 10 six-inch Prescolite non-airtight fixtures on the second floor ceiling, and another 11 mounted in cathedral ceilings. He may have plenty of light in those rooms, but he’s more concerned about all the air that’s leaking into the attic and rafter bays and the heat loss that goes along with it.
In a Q&A post at Green Building Advisor, Brown writes, “I have explored all the options. The attic is covered with (I believe) R-30 batts and about 12 inches of blown-in cellulose on top of that. They put additional batts all around the fixtures like a moat but not on top of them — not sure why, since they are IC [insulation-contact] rated.”
In the attic, he’s considered building airtight boxes around the fixtures, but access there is difficult. Most of the fixtures are next to joists, and building the boxes would require a lot of fussy work. A more attractive option is an LED retrofit kit, which the manufacturer claims is airtight.
“I assume that will greatly cut down on air flow to the attic,” he writes. “If I install those and add some insulation directly over the cans in the attic, is that a good solution for cutting air passage and bolstering insulation in those areas?”
The retrofit kits are also IC-rated, and Brown wonders whether he can stuff some fiberglass insulation into the fixtures before installing the LED kits. That, at least, would cut down on some of the heat loss through the fixtures.
“Lastly,” he continues, “I know there are a lot of factors at play here, but can anyone help ballpark for me annual heat loss costs per can in a situation like this? I’ve seen $5 to…