It's hard to say, but the changeover was noticeable: https://www.nytimes.com/interactive/2019/03/08/climate/light-bulb-efficiency.html https://www.nytimes.com/

It's hard to say, but the changeover was noticeable: https://www.nytimes.com/interactive/2019/03/08/climate/light-bulb-efficiency.html https://www.nytimes.com/interactive/2019/03/08/climate/light... When you have a technology in very nearly every home in the country and used daily that you can replace with something a whopping 85% more efficient it adds up.