Things to consider when purchasing an bath exhaust fan – Don’t sacrifice on quality.
Size CFM Required:
Bathroom fans should have 1 CFM for every square foot of floor space in the bathroom.
Consider installing a fan with light over an existing light fixture for easier wiring and convenience.
Sound levels are rated in sones where the lower the rating number, the quieter the fan. Typical economy fans are rated at about 4.0 sones or more while any fan rated 1.0 sones or less is very quiet (1.0 sones is roughly equivalent to a modern refrigerator).
As you shop for a fan, you'll probably want to consider noise level and choose a quieter model. Bathroom fans that sound like jet engines can really retract from the peaceful escape that is your bathroom.
These days, efficiency is top of mind when you shop for any home appliance or system. Fortunately, exhaust fans have become more efficient than ever. Energy Star bathroom fans, in particular, use 70% (yes, 70!) less energy than conventional non-Energy Star models. This certainly contributes to low energy costs. They must also meet qualifications for low sound emission, low wattage consumption, and powerful but efficient performance under static pressure. Choose an Energy Star bathroom exhaust fan to get the most bang for your energy bucks.
Broan Bathroom Exhaust Fans Catalog