The MicroEnv is a compact and simplistic environmental monitoring sensor, based on the ESP32-C3 and the Sensirion SGP41 and SHT45 sensors, using ESPHome for integration with HomeAssistant

Use a MicroEnv near a source of emissions to monitor air quality, or as a general room environmental tracking sensor. It is, in effect, a cut down version of the environmental sensor package of my Supersensor 2.x project in a much smaller footprint.

Power is provided by USB-C, though a very slim connector is required when using SMD soldering without a buffer.

The Sensirion sensors are elevated with through-hole pins, to ensure optimal distance between the (warm) board and the sensors themselves. You can either directly solder the sensors to the board or, as I do, use 4-pin female sockets for easy changing should it be necessary.

Parts List

Qty	Component	Cost (mid-2025 CAD, ex. shipping)	Links
1	GY-SGP41	$9.58	AliExpress
1	GY-SHT45	$5.67	AliExpress*
1	ESP32-C3	$3.12	AliExpress
2	Female 4-pin header	$0.37 ($14.99/40)	Amazon
1	Custom PCB (JLC)	$0.50 ($5.00/10)	GitHub
TOTAL		$19.24

* Ensure you select the correct device on the page as it shows multiple options.

Configurable Options

There are several UI-configurable options with the MicroEnv to help you get the most out of the sensor for your particular use-case.

Temperature Offset (selector, -30 to +10 @ 0.1, -5 default)

Allows calibration of the SHT45 temperature sensor with an offset from -30 to +10 degrees C. Useful if the sensor is misreporting actual ambient tempreatures. Due to internal heating of the SHT45 by the ESP32, this defaults to -5; further calibration may be needed for your sensors and environment.

Humidity Offset (selector, -20 to +20 @ 0.1)

Allows calibration of the SHT45 humidity sensor with an offset from -20 to +20 percent relative humidity. Useful if the sensor is misreporting actual humidity.

Home Assistant View

This image shows the various available sensors in Home Assistant.