Let's suppose everybody currently owns a 2200W vacuum, and immediately throws it in the bin and buys a new 1600W model. (Note that this is unrealistically optimistic... people will continue using the existing vacuums that they own with higher power ratings until they break, and they are allowed to do this.)
How often do you use a vacuum for? Let's say 1 hour per week.
The power difference is 600W, one hour per week, so each household will save 31.3 kWh per annum. (Or about $6.20 per year assuming 20c/kWh, assuming no cost to buy a new vacuum - maybe the government energy fairy just brings it to you for free.)
This also assumes, of course, that vacuuming time remains constant with the lower-powered unit.
OK, how many households are there in the EU? I'd guess maybe 100 million?
Total annual energy saved across the whole EU will be about 3.13 TWh per year (assuming immediate replacement of all vacuums, no increase in cleaning time.)
That's about the equivalent of 350MW of generation - so about 1/3 of a typical fairly large coal-fired or nuclear power plant.
In other words, if the entire EU can build just one more nuclear power plant to replace a coal-fired plant, that contribution to replacing coal use will be about 3 times greater than this entire vacuum cleaner mandate.