PurpleAir Homebridge Accessory Plugin

This is a Homebridge accessory plugin for monitoring air quality in Apple HomeKit. It creates virtual HomeKit air quality sensors based on real PurpleAir sensors. Once setup, you can also configure home automation based on air quality changes.

This project was inspired by SANdood's homebridge-purpleair, but with a few changes:

1. Support homebridge-config-ui-x so the entire project can be configured in its UI.
2. Support private sensors.
3. Support VOC sensor reading.
4. Support different averages, from realtime data, all the way to 1 hour average.
5. When the sensor is opened by HomeKit, this plugin will dynamically try to refresh the sensor values. However, it reuses the last updated value if it was fetched within 30 secs. This was done to prevent sending too many API requests to PurpleAir's servers. If the sensor is not opened by HomeKit, the plugin will update its value every 5 minutes by default.
6. Allow reporting AQI value instead of PM2.5 density in HomeKit. The author is more used to reading AQI value, but HomeKit has only a field for PM2.5 density value. The plugin allows you to configure displaying AQI value in the density field.
7. Work with multiple sensors.
8. Rewritten in TypeScript, with some unit tests.

Installation

The easiest way to install is through homebridge-config-ui-x UI. Search for homebridge-purpleair-sensor and just click install. Once done, configure it using the UI, and restart homebridge.

If you want to install manually via the command line, run the following:

sudo npm install -g --unsafe-perm homebridge-purpleair-sensor

sudo service homebridge restart  # replace this with the command you need to restart homebridge

Configuration

You can configure this plugin using homebridge-config-ui-x UI.

If you want to configure manually by editing config.json file, add one entry per sensor you want to add to HomeKit to the accessories section. As an example:

"accessories": [
    {
        "accessory": "PurpleAirSensor",
        "sensor": "12345",
        "name": "PurpleAir Indoor Sensor",
        "conversion": "None",
        "averages": "realtime"
    },
    {
        "accessory": "PurpleAirSensor",
        "sensor": "54321",
        "name": "PurpleAir Outdoor Sensor",
        "conversion": "None",
        "averages": "10m"
    }
],

You can set the following fields:

• accessory (required): must be PurpleAirSensor
• sensor (required): the sensor number. Find the sensor number by going to PurpleAir's map -> click on a sensor -> Look at the URL. It's the number right after 'select='.
• name (required): name of the sensor.
• key (optional): API key for private sensors.
• conversion (optional): Conversions help accomodate different types of pollution with different particle densities. Supports the following values:
  • None (default)
  • AQandU
  • LRAPA
  • EPA
• averages (optional, default realtime): sensor reading averages, only used with None and AQandU conversions. Supports the following values:
  • realtime
  • 10m: 10 Minute Average
  • 30m: 30 Minute Average
  • 60m: One Hour Average
• aqiInsteadOfDensity (optional, default false): if true, use the PM2.5 density field to report AQI instead.
• updateIntervalSecs (optional, default 300): number of seconds the plugin will wait before updating the sensor value again.
• verboseLogging (optional, default false): if true, log all information at info level so you can see through homebridge logs what the plugin is doing without running homebridge in debug mode.

Development Notes

A few useful commands:

sudo npm run watch

# publish new version
npm login
sudo npm publish

Changelog

• 1.6.2: Support EPA conversion.
• 1.5.0: Support private sensors.
• 1.4.0: Add AQandU and LRAPA conversions.
• 1.3.0: Added unit tests for parsing and ability to report averages in addition to realtime values.
• 1.2.0: Verbose logging option.
• 1.1.0: Allow reporting AQI value in the field for PM2.5 density. I personally like the AQI value because I'm more used to it, but technically HomeKit only supports PM2.5 density rather than AQI.
• 1.0.0: Initial version.