Ori Skloot of Advanced Home Energy in Berkeley (www.advancedhomeenergy.com) came to my house and took care of my recessed-can problem. California houses, especially the new ones, have a lot of recessed-can lights, also known as downlights. New California houses have an average of six downlights in their kitchens alone! My house was built without them in 1951, but the previous owners had seven of them installed.
Homeowners pay a heavy price for well-lit kitchens unless those downlights are air sealed and insulated. When Ori and his crew depressurized my house by 50 Pascals––equivalent to the pressure drop inside created by a strong wind outside––by closing all the windows, covering all the registers, and installing a "blower door" in the front door, we found that my house was leaky. Home performance professionals like Ori use "air changes per hour," or ACH, to gauge the leakiness of a house. Before taking care of my leaky can lights, my house measured .72 ACH. In other words, the entire air volume of my home was replaced by outside air--in this case, about half of it coming from my attic through the downlights--about every eight minutes. The American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE) recommends .3 ACH (at 50 Pascals) as a good measure for healthy indoor air. They also recommend that fresh air come from outside in a controlled fashion, not from attics or crawlspaces. Believe it or not, outside air is an awful lot cleaner than inside air, and we spend about 90% of our time inside some building.
After sealing all of my downlights, Ori fired up the blower door again and measured .4 ACH--not perfect, but much better than before. To tighten up my 56-year-old-house house even more would require more time and effort than would be cost effective. Ori and crew then sealed all the ductwork in the attic and "blew in" several inches of cellulose insulation. Now my wife and I are breathing easier and ready to be snug in our house this winter. And now that we won’t have to heat the attic, our heating bills will be about half what they would have been without the retrofit.
(For a great article on recessed-can lights, go to: www.pct.edu/wtc/pdf/BB0502-Air-Leakage-in-Recessed-Lights.pdf.)
Jim Gunshinan is Managing Editor of Home Energy Magazine. He holds an M.S. in Bioengineering from Pennsylvania State University, State College, Pennsylvania, and a Master of Divinity (MDiv) degree from University of Notre Dame.