Researchers modelled eight ways of producing the same national quantity of eggs, comparing furnished cages, barns, conventional free range, and organic free range. Their results put organic eggs at the wrong end of three major environmental measures. Producing 1kg of organic free-range eggs was estimated to generate 3.52kg of carbon dioxide equivalent, compared with 1.80kg from furnished-cage production. Scaled up across the UK, an entirely organic free-range industry would produce an estimated 2.316 million tonnes of carbon dioxide equivalent annually. Free-range and organic hens generally consume more feed for every kilogram of eggs produced, while organic feed requires more land.