A Chinese researcher at a state-owned energy think tank said that in the future the amount of energy it takes to produce a product will be found on product packaging.

Mr. Jiang Kejun said the research institute in Beijing is working to analyze the energy consumption of products used in people's daily lives. "For example, the amount of energy used to make an A4 size sheet of paper is about 0.1 kilowatt-hours," he told a Chinese publication.

Well, that energy tag may help plastic bags regain some share lost to paper bags, since the production of paper bags uses more energy than plastic bags.

But, researchers, especially those who advise governments on policies, should really look at the whole picture rather than one single parameter. What about carbon footprint? What about reusability? What about recyclability?

And, how much energy does it cost to produce the energy tag, starting with figuring out the amount of energy in every commodity? Will it be worthwhile?