Quiet Ventilation. Broan’s new Ultra Silent Series QTRE080R retrofit bath fan is designed to be installed from below the ceiling. It runs quietly at .8 sone while exhausting 80 cfm and is Energy Star rated. According to the manufacturer, it costs only about $1 per year to operate. You can find it online for around $100. Broan-NuTone, 800/558-1711, broan.com.