Gainesville Sun: Hernan Vera has become obsessed with his carbon footprint – the measure of the impact our activities have on the environment and especially climate change. In the past year, he has had solar panels installed on his northwest Gainesville home, refitted his house with low-energy light bulbs and hired an air conditioning contractor to come out to his 2,700-square-foot residence to plug leaks. “Once you get going in this thing, you want to save energy in everything you can,” said …