An alternative interpretation of this passage is that it refers to corporate election. Corporate election is often used as an alternative interpretation of passages dealing with election.
It is the belief that God elected the Church itself to be the body of Christ and to receive salvation. For example:
For the grace of God that brings salvation has appeared to all men. It teaches us to say “No” to ungodliness and worldly passions, and to live self-controlled, upright and godly lives in this present age, while we wait for the blessed hope—the glorious appearing of our great God and Savior, Jesus Christ, who gave himself for us to redeem us from all wickedness and to purify for himself a people that are his very own, eager to do what is good. - Titus 2:11-14 (NIV)
This is in contrast to the belief that God predestined the individuals who would become members of the Church (I use the words "members" and "Church" in the spiritual sense - not speaking of membership in any particular church, but of membership in the body of Christ).
In this view, the "us" in the passage would refer to all believers, in the corporate sense. For example (with purely illustrative purpose):
Who hath saved [His Church], and called [Christians] with an holy calling, not according to works, but according to his own purpose and grace, which was given [to the body of Christ] before the world began.
I don't know Greek, so I'm not sure how well this illustration fits with the tenses used in the original text.
You can read more about corporate election here.