Garage door + cold alert playbook

Alert when a bay door stays open while temperatures drop: door contact ingest, combined alert rules, and household response steps.

Bench grinder on a wooden workbench against a brick garage wall with tools
Workshops and garages swing harder than living space: placement beats sensor brand. Photo: Shixart1985. CC BY 2.0

An open garage door on a cold night can drop indoor probe readings fast: sometimes before your main freeze threshold would have warned you on temperature alone. This playbook wires a door contact plus a combined alert rule so the household gets a clear signal to close the bay.

Hardware options

  • Shelly door input. HTTP POST on open/close (see ESPHome & Shelly recipes).
  • ESPHome binary sensor: include door in the same ingest POST as your temp probe.
  • Home Assistant: mirror an existing binary_sensor through the HACS integration or MQTT bridge.

Map sensors in Devices

  1. Confirm at least one temperature probe reports in Home.
  2. Confirm the door key shows Open/Closed (bool kind).
  3. Label probes clearly (for example “Garage door”, “Crawlspace”): rules can filter by label substring.

Create a combined rule

Open Dashboard → Alerts, expand Rules, and add a rule with all of these conditions:

  • Door open: fires while the contact reads open.
  • Temperature below threshold: uses your freeze threshold (or set a custom °F value per condition).
  • Optional: Door open longer than (minutes) instead of instant door open: reduces noise from quick trips to the car.

Example name: Garage door open while cold. Save alert settings, then send a test alert from the same page.

When the alert fires

  1. Acknowledge the alert so escalations pause if you use playbooks.
  2. Close the door: readings often recover within minutes.
  3. If temperature keeps falling, follow the cold-snap playbook (space heaters, faucet drip, household SMS).

Tuning tips

  • Use door open duration (15–30 min) if short openings should not notify.
  • Add rate drop or forecast triggers for regional cold snaps without relying on the door alone.
  • Enable SMS or push (Pro) when email is not loud enough at night: see alert channel cookbook.

FAQ

Can I alert on door open alone?
Yes with a door-open rule, but pairing door + temperature below threshold reduces false alarms when you are working in a warm bay or shop.

Where do I create the combined rule?
Dashboard → Alerts → Rules. Add conditions for door open (or door open duration) AND temperature below your freeze threshold, then save and send a test alert.