From Robert Whitcomb’s “Digital Diary,’’ in GoLocal24.com

There’s lots of wasted space on the flat roofs of some big buildings, such as hospitals and old factories. They can be put to use for such things as solar panels -- or rooftop farms. That’s what the Boston Medical Center has been doing for the past three years.

EcoWatch reports that the hospital’s rooftop farm produces about 6,000 pounds of food a year, with 3,500 pounds slated for its Preventive Food Pantry, which provides free food to low-income patients. The rest goes to Boston Medical’s other patients, its cafeteria, a “teaching kitchen and an in-house portable farmers market,” the publication reports. More than 25 crops grow in the 2,658-square-foot rooftop garden, said to be the biggest in Boston.

The hospital even offers some courses to patients, employees and their families in how to grow their own healthy food. I love it when previously wasted space – rooftops, parking lots of closed stores and factories, etc. -- is used so productively.