The green idea here is that you will be using less fuel by not having your burner going full whack to keep the water boiling. But this method goes against all the conventional wisdom around cooking pasta, that if it's not kept rapidly boiling in lots of water, it will end up in a mushy, gooey mess. As Lynne Rossetto Kasper said: my Italian ancestors are flipping in their graves!
Does it work? Yes! Beautifully! I now use this method every time I cook pasta and I have yet to have any problems with taste or texture. As a matter of fact, I recommend checking for doneness a minute or so before the times recommended on the pasta package.
I have not tried this with filled pastas (such as ravioli) or less traditional pastas, such as those made with rice or quinoa, nor have I tried it with whole wheat pasta. But it's worth experimenting with. I cannot imagine that the same principles don't apply and some of the alternative pastas are a little more fragile anyway, so perhaps less time vigorously boiling will be helpful.
How much fuel do you save and how much of a difference does this make in the big picture? Probably not a whole lot on both counts. But things add up and a little less fuel here and there is a good, painless way to start reducing your 'cookprint.' This method is also helpful for those who have limited space on their stovetops or who cook off of hotplates, as the pasta pot can be removed from the stovetop, freeing up more room. It might be good for camping, too, where cooking space is often at a premium. Ms. Heyhoe also recommends this method for blanching vegetables.
(Image: Dana Velden)