Drone delivery becomes a big opportunity for start-ups.

CNBC correspondent Jane Wells spotlights five fields she asserts are especially susceptible to entrepreneurial opportunity: drones, food, babies, health, and the environment.

Wells looks at the convergence of demographics and tech advancement as fertile ground for new business start-ups, which she notes account for eight million payroll additions in the past 25 years, while large corporations have cut headcounts by a total of four million in the same time period. Wells writes of one such opportunity area for entrepreneurial types:

The "green" house is hot. Environmentally friendly building practices and supplies are becoming a natural part of the American construction industry. The U.S. Green Building Council estimates about 1 in 4 new homes is being built with at least some green building practices. The numbers are similar in the hotel space. The organization — whose mission is to promote environmentally sound building — says "green construction is outpacing that of traditional construction and is poised to create more than 3.3 million U.S. jobs and $190.3 billion in labor earnings by 2018."

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