Die Tür wird gleich geschlossen, damit es drinnen warm bleibt.

The door will be closed in a moment so that it stays warm inside.

Breakdown of Die Tür wird gleich geschlossen, damit es drinnen warm bleibt.

• die Tür: the door
• es: it
• warm: warm
• damit: so that

Questions & Answers about Die Tür wird gleich geschlossen, damit es drinnen warm bleibt.

Why does the sentence use wird ... geschlossen instead of schließt?

wird ... geschlossen is the present tense passive in German: werden + past participle.

• Die Tür wird geschlossen. = The door is being closed / is closed (by someone).
  It focuses on the action/result (the door getting closed), not on who does it.
  If you said Die Tür schließt (sich), that’s more like The door closes (itself) (e.g., an automatic door).

How do I know this is passive, and where is the “past participle”?

You can recognize passive because of: 1) werden as the auxiliary (wird)
2) a past participle at/near the end (geschlossen)
So the “passive frame” is wird ... geschlossen.

Why is Die Tür in nominative (subject form) if someone is closing it?

In the passive, the thing that would be the direct object in the active becomes the subject:

• Active: Jemand schließt die Tür. (die Tür = accusative object)
• Passive: Die Tür wird geschlossen. (die Tür = nominative subject)
  The person doing it is optional and often omitted.

How would I add “by someone / by the staff”?