An employee that sat around "taking up space" would not last long in today's competitive business environment. Yet that's exactly what most offices do: sit around waiting for their owners to come back.

Employees seem to work everywhere but at their desks these days. Whether it's meeting with clients or each other, whether it's working at home or in a hotel, employees are more mobile than ever. Which means that, for most of the day, all of those "offices" are actually very expensive closets.

Try the "10 o'clock Test" at your office:

Step 1: walk down the hall at 10 a.m. and see how many employees are actually in their offices.

Step 2: realize that real estate is 8% of the average company's gross revenues.

You do the math.