Mr. Tight Watt asked for assistance from Jean Eells, E Resources Group in Webster City. E Resources Group provides education on the environment and energy and also provides evaluation services. Jean provides the answers below.
Q: I get a draft through my bathroom exhaust fan. It is vented in my attic and I also have a dryer vent cap on the end. I also get a draft through my ceiling can lights. I only get a draft when the wind blows from a certain direction. I have 12 inches of fiberglass blow-in insulation in my attic with soffit vents and roof vents. Do I need to add more insulation? Alan
A: From Jean: Each problem Alan mentioned has a different cause and solution unrelated to the amount of insulation. I’ll address each one separately.
Bathroom fan. Without inspecting the fan, I would suspect that the bathroom vent fan damper is most likely stuck open and probably will need replacement unless there is an obvious and fixable reason it is stuck.
When shopping for a new fan be aware that cheap fans often develop damper problems, so spring for a higher quality fan and you should not have a draft. This broken fan is like having a small window open to the attic and to the outside 24/7 in all temperatures. It pays to purchase a fan with a good damper.
Ceiling can lights. Can lights are a design feature with hidden fixtures but also with higher hidden costs of operation when they are installed in ceilings open to an attic. Having can lights in your home is like throwing money in the wind. This type of light leaks tremendous amounts of expensive heated (and cooled) air into your attic, costing you money year-round.
When doing blower door tests, we rarely find situations where can lights don’t leak significant amounts of air. We have seen some new homes with as many as 25 of them throughout halls and vaulted ceilings. From what we observe, it’s a high price to pay for looks.
One reason for the leakiness is that insulation has to be kept away from the lights, because the incandescent bulbs generally used in the can fixtures get really hot. The incandescent bulbs waste energy and give off large amounts of heat, which can cause a fire if insulation is placed close to the fixture. Because there is no insulation around the canister, the cold (or hot, depending on the time of year), drafty air can flow right into your home.
The solution to this problem must be matched with what you are willing to do.
- You can switch to compact florescent bulbs (CFLs), which don’t generate the heat that incandescents do. If you make that commitment, you can then ask a knowledgable contractor to help you insulate safely in the attic around the canister. However, if you’re not confident that compact fluorescent bulbs will always be used in those fixtures, you shouldn’t make them tighter. Adding insulation over the top of the lights, then switching back to incandescent bulbs is a strong fire danger.
- Another option is to replace the canisters with another style of light fixture. In the long run, this could well be a cheaper option (saving energy each and every month) and is definitely a safer option.
Insulation. If you’re planning to stay in your home a couple more years, adding insulation is generally a good investment. Twelve inches is a reasonable amount though some houses have 24 inches where there is adequate room. Cellulose can settle and depending on the skill of the original installer it can settle quite a lot.
Check that there are still 12 inches and that it has not blown around from wind coming in the roof and soffit vents.
For more information, contact Jean Eells:
Editor's Note: Check out more recent information on recessed lighting in the Recessed Lights article on this site.
Ask Mr. Tight-Watt a question or view other questions Mr. Tight-Watt has answered