How do you save energy with power factor correction?

Power-factor correction doesn't save energy.

Power-factor correction is used to reduce that magnitude of the current drawn from the supply in order to minimise the cross-sectional area of the supply conductors and associated equipment -thus keeping down the cost of the supply circuits which are owned by the supply company.

Power-factor correction doesn't apply to homes, but only to larger commercial or industrial premises. The electricity supply company will negotiate a value of power factor for the load, and apply a penalty charge to the customer if his load is not kept within that agreed value.