Originally Posted by bart4858:
“How exactly did that shower-head save £250 a year? (My own shower uses unmetered water and uses a fixed amount of electricity. The only way to save would be to have it on lo-power, which I can already do (if I want a trickle), or have shorter showers)”
I believe that energy saving shower heads work by providing a higher pressure flow which spreads out well and are supposed to create a feeling/illusion of "a shower" with a smaller amount of water actually flowing. So that when people turn the shower on, they, on average, choose a lower water flow When I've used similar things, I found that anything more than a small amount of water creates fine high pressure jets on my head, which are uncomfortable.
In other words, the shower heads work more on the psychology of the person taking the shower, rather than the basic physics of heated water.
Whether the product pitched actually works that way, or actually works, I don't know.