Which happens to be: Como utilizar

Hello, I've seen this expression many times and I don't know exactly how to use it. Could you all help me?

Exemples:

- He found the space, which happens to be across the street from his house.

- This would phase out Social Security, which happens to be anti-social and insecure.

- I'm currently using an iPhone 7, which happens to be my first Apple phone.

- Colombia's position, which happens to be the same as the US, is the only sensible one.

- He climbed Mount Rainier, which happens to be the highest point in Washington, in 1993.