From the newsletter of Northwest Energy Star (Q32014):
Bibs vs. batts: Who ya got?
Recently, some blown fiberglass products were shown to offer the same resistance to airflow when blown to a density of 2.3lbs/cubic foot as cellulose does at 4lbs/cubic foot. Energy Trust of Oregon was intrigued by these lab results and set out to see if they translated to the real world of production builders.
To find out, Energy Trust conducted a study in 2013 of 40 new homes comparing the airtightness of homes using batt insulation in the walls with homes using the blown-in wall system. On average, the blown-in wall system proved to be 1 ACH50 lower, resulting in a tighter home. Additionally, the houses with the blown-in wall system all had a higher average R-value (R-23) than the homes with batted walls (R-21). While lower infiltration and higher wall R-values are important, the blown-in systems also resulted in lower levels of inside noise. Interestingly enough, this was the feature homebuyers commented on the most, which is ultimately what convinced many builders to adopt the technique for all their new homes. To quote one builder: “I can sell quiet.”