I want to add another general warning to this whole confusing global push towards carbon reduction commitment saving energy, saving money, saving the planet. Be very careful of new packages from either independent companies or energy suppliers who are offering a 'suite of products' to 'measure, monitor and minimise' your energy consumption. I'm not naming any names but the packages are a combination of what Npower and British Gas are offering.
This newish market category is called 'business energy management' and they will soon all be at it, offering you smart meters and ways of optimising your equipment by switching on and off lights, and ramping up and down the heat.
Some of these companies will mention the Carbon Trust's interest-free loans which in themselves are fantastic, but they are not linked to any particular company. I know one retailer who signed up for one of these packages and it cost him five figures. A specialist audit later showed that it should have cost only four figures.
I'm certainly not decrying the theory of saving energy, money and planet. I'm sure Sainsbury's is doing it and is not getting ripped off. But it is usually the smaller, softer targets that get stitched up.