A lot of the ratings are utterly ridiculous.

For example, a Vax upright with no brushroll off function got a higher rating for hard floor cleaning than a straight suction Henry. An S-Class Sebo got a lower emissions rating that an air-clean Miele.

The problem with the ratings is that they're carried out by the manufacturer to guidelines published by Brussels. Whilst I agree with the legislation and that vacuum motor power needed to be brought down, and also I agree with a ratings systems and a minimum requirement for performance to be able to sell it, I don't agree with the way that the tests are being carried out. All vacuums should be tested in the same place, using the same floortypes and the same variables. There's too much inconsistency in the testing.

I've always thought 900w is a ridiculous number. I'd say 1000w or 1200w is more realistic and both are nice, even numbers. 900w just seems completely random, although it's entirely possible to generate high suction power with under 900w as the new Numatic vacuums are proving.

1200 is MORE than enough. Your beloved Dyson DC41mk2 is only 700w and the new Henry's are 580w. Why does a vacuum need to use more than that if it's entirely possible to get high performance with a lower wattage motor? Lowering the wattage also results in motors that don't run as hot and will (hopefully) last longer.

It's a combination of things, IMO. The reason dirty fan cleaners tend to perform better on carpets, is because the suction, though not as strong as clean air, has less far to travel. The nearer you can get to the fan, the stronger the suction will be. If a vacuum has loads of windy tunnels and tubes between the cleanerhead and the motor, it won't perform as well. The more direct route of the suction, the better.

The fan itself is also something to take into consideration. The suction on Oreck uprights is pretty crap, largely because the fan is so tiny. Then there are twin fan designs, the quality of the motor, materials the fan is made out of and other such things to consider. I've always viewed high wattage as a cheap cop out for vacuum manufacturers to get away with using cheap motors and poor designs.

Take a look at the older Hoover uprights. The early models, like the 300 or 725, only had about a 300 watt motor. Even with this low wattage, they still cleaned carpets like a pro, and still do if they're in good shape. The American Electroluxes had 535 watt motors for several years until the 1205 was introduced, which had a "high performance" motor. I have a 1949 Electrolux Model XXX that is only 535 watts, and it does a perfectly good job cleaning floors and area rugs. 

Personally, I don't think any vacuum needs more than a 700 watt motor to do an adequate job at cleaning your home.

Who cares how much power a vacuum uses? What is the big deal with cutting down on power, and on vacuum cleaners of all things! 

....we do.

Ok, great! Different strokes for different folks! 

And LOL Marcus, send some of that global warming here! It was SEVEN degrees Celsius last night, in FLORIDA!! 

Hahahaha, it's MY TURN to have sunshine!! MUHAHAHA! 

Global warming concerns aside (quite frankly, I don't think my vacuum is enough to melt a polar icecap all by itself), I think lowering the wattage will eventually result in more interesting designs and more reliable machines.

Definitely the biggest market shake up we've had since the bagless craze hit in the mid-90's, 20 years ago! It's an exciting time to be a vacuum enthusiast.