Here are general size guidelines from the American Lighting Association:

What price comfort?

Prices for ceiling fans range widely, from $20 to $100 for basic, two-switch varieties, to $3,000 and up to $12,000 (yes, really) for entire fan systems consisting of several high-end fans integrated into an architectural design.

However, most folks will be happy in the $200 to $600 range, which gets you a better-designed machine and warranty. Extras, such as designer shades, polycarbonate blades, and special finishes for woods and metal, can tack on a few hundred dollars.

What to look for

• Blade pitch. The wider the blade (5 inches is good) and the higher their angle—called “pitch”—the more air gets moved. Higher-end fans have a blade pitch of 12 to 14 degrees.

• Blade finish. Make sure the factory has treated the blades with a moisture sealant to prevent wooden blades from warping and peeling, and metal blades from scratching and tarnishing.

• Motor quality. Better fans come with motors that have sealed and lubricated ball bearings, which require little maintenance, if any. More expensive models feature heavy-duty windings, precision engineering bearings, and die-cast housings, which vibrate less and are good-looking.

• Energy Star-rated fans. To qualify, fans must have a minimum airflow of 1,250 CFM on low speed and 5,000 CFM on high speed. They must come with a minimum 30-year motor warranty; one-year component(s) warranty; and 2-year light kits warranty. Energy Star-rated fans are 50% more efficient than conventional ones.

Fans to be used outdoors or in high-humidity areas such as bathrooms or laundry rooms must be damp-rated or wet-rated.

Laura Fisher Kaiser writes the blog Secret Science Geek, is a contributing editor of Interior Design magazine, and a former editor at This Old House. She couldn’t survive sticky summers in Washington, DC, without the gossamer breeze of ceiling fans.

Read more: http://www.houselogic.com/articles/ceiling-fans-keep-your-cool-save-money-too/#ixzz1O2z20UEq