After four months of a Sustainable Pittsburgh challenge posed to local businesses to “green” their buildings and practices, the organization announced the aggregate energy savings on Friday.

Matthew Mehalik, Program Manager for Sustainable Pittsburgh, said the fifty plus companies participating in the challenge have made changes such as swapping the types of light sources they use, reducing water use in their office spaces, recycling, having employees tele-commute, and encouraging their employees to think about their energy usage in more critical and thoughtful ways.

So far, the changes made have resulted in a considerable amount of energy reduction.

“It’s the equivalent of taking off the grid 437 homes’ annual family electricity usage. That’s about the size of Regent Square in Pittsburgh, removing Regent Square from the grid for a full year,” he said.

The amount of energy reduction is tabulated by a form distributed the Environmental Protection Energy.