One expert says it’s more cost effective to keep hog buildings at the optimal temperature during the winter. ISU Extension Swine Specialist Tom Miller says if a building isn’t warm enough, it’s going to take a lot more feed to keep hogs in their thermal neutral zone, which is also affected by humidity. He explains if you’re raising 2,400 pigs, each weighing around 220 pounds, they’ll need an extra three and a half tons of feed each week if the building is below the optimal temp.