Do you work in an open-plan office? If you're in the United States, the odds are that you do: over 70 percent of Americans now have open-plan offices. In theory, people are collaborating more. But the problem is they're also less focused, less happy, and more likely to get sick. Gensler, the design firm, just finished a new study on office design and says we don't need to go back to old-school offices, but the best workplaces have mixed spaces.