Herald: Supermarket fridges and freezers are environmentally unfriendly, spewing out bad gases that make up more than a quarter of the companies’ total carbon footprint. The HFCs (hydrochlorofluorocarbons) can have as much as 4000 times more impact on global warming than carbon dioxide, say green campaigners. None of the 10 high-street stores fared well in a survey that had Iceland scoring an alarming -1 out of a hundred, closely followed by rivals Lidl (0 points) and Aldi …