There are millions of pool pumps wasting huge amounts of energy; and it doesn't have to be this way.
That’s possible to reduce the energy consumption of a pool pump to values as high as 80%...
Single-speed pool pumps vs. Multi-speed pool pumps
Most pool pumps are single-speed, which means that they can’t change their flow rate. In other words: during most of their operational time the pumps will be delivering more water and consuming more energy than is required to filter the pool's water. They are wasting energy.
The problem is not a sizing issue. Oversizing is common, but since many pool pumps are used for other purposes besides filtration (pool heaters, spa jets, chlorinators, and so on...) they have to be sized to handle them. And since single-speed pumps can't adjust their flow rate, they become extremely inefficient.
The only way to solve the problem is by installing a multi-speed pool pump. These pumps inherently more efficient, largely because they can change their flow rate and respond to the needs of the moment.
So, consider an energy-efficient multi-speed pump if you are going to buy a new pool pump, or renovating your pool. Multi-speed pumps cost a bit more than old and outdated single-speed pool pumps, but they worth their price.
Some pool experts like to stress that you may not need a multi-speed pump for high energy savings. You can achieve them by reducing the size of a single-speed pool pump to the minimum, by using 1) the largest filter suitable for your pool 2) a large-diameter pool pipe, 3) a short length-pipe and 4) 45º elbows (or flexible pipe) instead of 90º elbows.
And that's true, in some cases.
Such design allows a smaller pump, that will consume a fraction of the power: having a 0.75 hp pump instead of a 1.25 hp pump can reduce the electricity consumption by 30-50%. But things will not be as straightforward or easy.
Other features besides the efficiency and The type of pool pump
Anyway, there are other factors that are important for swimming pool energy savings. You will not be able to reduce your pool pump energy bills to high levels without other measures.
If you're one of these people who keep their pumps running 24 hours per day, your bills will always be high, even if you use the most advanced and energy-efficient multi-speed pump. You should limit it to 3 hours per day, or less...
See, on these issues: Swimming pool Energy Improvements.