I highly doubt it would cut our emissions by 25%. Maybe 2.5%.
Relates to emissions from peoples homes and doesnt include use of other energy such as gas.
Light bulbs use almost as much energy as cars.
Add in industry use of lighting, that in some instances means 24/7 and its a hell of a lot of power. Just look at the number of empty office blocks that have their lights left on.
In the UK alone, it has been estimated that the use of energy-saving light bulbs, in suitable applications, would reduce the amount of carbon dioxide released into the atmosphere by 2.3 million tonnes per year (2.3 Mt CO2).
Such an annual saving would be equivalent to 8-21% of the emissions reduction the UK government has stated that it wants achieved by 2010.
http://news.bbc.co.uk/1/hi/sci/tech/4922496.stmNot quite a 25% cut but it does meet what the government wants at the top end. Add in other options and it would be possible for a 30% plus cut in emissions.
Real problem is that Chinas increase in power use needs far more than that from a single year. No matter how hard we put our brakes on its the Americans and Chinese who are the real problem.
I havent changed a low energy bulb in five years and I still have the first one I got given after filling in a home energy assessment form - its still working too