Sensor types

 Ah, my mistake! You are looking for a complete layout of all the different physical sensors available for building out a smart home system.

Think of sensors as the nervous system of a home—they gather raw data (temperature, movement, moisture) and pass it to your hub so your automation scripts can actually do something with it.

The complete spectrum of residential sensors available today breaks down by function:

## 1. Presence & Motion (Where are people?)

 * **PIR (Passive Infrared) Sensors:** The classic motion detector. It senses changes in heat signatures when someone walks by. Best for high-traffic zones like hallways where you only need a quick trigger.

 * **mmWave Radar Sensors:** High-frequency radar that detects micro-movements like breathing. It knows you are still in the room even if you are sitting perfectly still reading a book or sleeping.

 * **Pressure Mats:** Thin sensors hidden under rugs or mattresses. Excellent for triggering an "arm security" script when you get into bed or turning on floor lighting when your feet hit the rug.

 * **Ultrasonic/Laser Distance Sensors:** Measures the exact distance to an object. Commonly placed on garage ceilings to read the distance to the roof of your car, letting the system know if a vehicle is parked inside.

## 2. Perimeter & Security (Is the house secure?)

 * **Contact (Magnetic) Sensors:** A two-piece sensor placed on doors, windows, gates, or drawers. When the magnetic connection breaks, the system knows it is open.

 * **Vibration / Glass-Break Sensors:** Glued directly to window panes or large glass doors. They read the specific acoustic frequency or physical shock wave of breaking glass to trip an alarm before an intruder steps inside.

 * **Tilt Sensors:** Frequently mounted to garage doors or mailboxes to read horizontal versus vertical positioning.

 * **RFID / NFC Tag Scanners:** Small pads near entryways. Tapping a keychain fob or your phone against it acts as a physical token to disarm systems or run a specific user routine.

## 3. Climate & Comfort (How does the air feel?)

 * **Temperature & Humidity Sensors:** Often combined into small pucks. They drive smart thermostat zones, tell bathroom fans to turn on during a shower, or alert you if a wine cellar or refrigerator gets too warm.

 * **Ambient Light (Lux) Sensors:** Measures the exact brightness of a room in lumens. Essential for ensuring automated lights only turn on if a room is *actually* dark, or adjusting motorized shades based on solar intensity.

 * **Barometric Pressure Sensors:** Used mostly in backyard weather stations to predict incoming weather fronts locally.

## 4. Safety & Structural Health (Is the house safe?)

 * **Water Leak / Flood Detectors:** Flat pucks with metal pins on the bottom, placed under sinks, water heaters, and washing machines. When water bridges the pins, it immediately alerts you (or triggers an automated main water shut-off valve).

 * **Smoke & Carbon Monoxide (CO) Detectors:** Smart variants that don't just scream locally; they broadcast to your entire automation system to shut down the HVAC fan (so smoke doesn't spread through the ductwork) and turn on all lights.

 * **Combustible Gas Sensors:** Plugged into outlets near stoves or water heaters to detect natural gas or propane leaks.

 * **Radon Sensors:** Continuous monitoring devices for dangerous, odorless radon gas accumulation in basements.

## 5. Indoor Air Quality (IAQ)

 * **CO2 (Carbon Dioxide) Sensors:** Tracks stuffiness. High CO2 causes fatigue; hitting a certain threshold can trigger an HRV/ERV system or whole-house fan to pull in fresh air.

 * **VOC (Volatile Organic Compounds) Sensors:** Detects chemical airborne irritants from cooking, cleaning products, paints, or new furniture.

 * **Particulate Matter (PM2.5 / PM10) Sensors:** Laser-based sensors that count airborne dust, smoke, and pollen particles to dynamically ramp up air purifier speeds.

## 6. Utilities & Resource Management

 * **CT Clamps (Current Transformers):** Clamped directly onto individual circuit wires inside your main electrical breaker panel to read real-time energy draw (Wh and kWh) across the house.

 * **Smart Water Meters:** Clamped onto your main incoming water line to read the ultrasonic resonance of water flow, identifying silent toilet leaks or running garden hoses.

 * **Soil Moisture Sensors:** Spikes pushed into garden beds or potted plants to stop automated irrigation schedules if the soil is already damp from rain.

> **Pro-Tip on Deployment:** You rarely buy these all individually anymore. Most modern hardware options are **Multi-Sensors**—a single device the size of a matchbox that contains a PIR motion detector, a temperature sensor, a humidity reader, and a lux sensor all on one chip.