Xiaomi's new temperature and humidity sensor also measures carbon dioxide concentration. It has a large display and doesn't cost much

Afternoon fatigue, a heavy head, and declining concentration are often caused by stale air and a high concentration of carbon dioxide. The new Xiaomi Smart Temperature And Humidity Monitor 3 Pro aims to alert you before you feel it: in addition to measuring temperature and humidity, it also adds CO2 monitoring and color-codes to indicate, when it’s high time to open a window.

Carbon dioxide in a closed room rises surprisingly quickly – just closed windows, a few people, and a few hours are enough. However, a regular thermometer won’t detect it. CO2 measurement is the main new feature that distinguishes the 3 Pro model from previous generations.

New Xiaomi sensor brings CO2 measurement

CO2 measurement is handled by a low-power sensor from Sensirion, which operates on the principle of thermal conductivity and continuously monitors concentration. Xiaomi states a resolution of 0.1 °C for temperature, 1% for humidity, and 1 ppm for carbon dioxide for the new product – however, these are manufacturer’s values that we cannot verify ourselves.

Since a regular user is not familiar with ppm units, the thermometer translates the air quality into three colors. Up to 1000 ppm it glows green, between 1000 and 1500 ppm yellow, and above 1500 ppm red – red is a signal that it’s time to ventilate.

Larger display and connection to Xiaomi Home

The new product received a 3.6-inch LCD display, significantly larger than previous models (the smallest 3 Mini had around 2.1 inches). On one screen, it simultaneously shows the date, day, time, temperature, humidity, and CO2 concentration – you can switch between individual data points using a button on the side.

The Xiaomi Smart Temperature And Humidity Monitor 3 Pro works on its own even without a connection, but it fully integrates into a connected home. Via Xiaomi HyperOS Connect and a gateway with Bluetooth Mesh support, it sends values to the Xiaomi Home app, where you can find historical curves of temperature, humidity, and CO2. Based on these, it can then trigger other devices: when the carbon dioxide concentration exceeds a set limit, a Xiaomi smart speaker will remind you to open a window, and the sensor can pass temperature or humidity deviations to air conditioning, a direct heater, or a humidifier.

Power is provided by a single CR2450 button cell battery, which according to Xiaomi, lasts about a year. The device can be placed on a table, attached to a wall, or hung on a metal sheet thanks to its built-in magnet and included metal ring.

Price and availability

In China, the Xiaomi Smart Temperature And Humidity Monitor 3 Pro is launching via crowdfunding on September 21 and will cost approximately 360 Czech crowns (114 yuan). After the campaign ends, the regular price is expected to rise to 149 yuan, or about 470 Czech crowns.

Xiaomi's new temperature and humidity sensor also measures carbon dioxide concentration. It has a large display and doesn't cost much Adam Kurfürst News Adam Kurfürst News

The manufacturer has not yet said when or if the new product will reach the Czech Republic – however, previous generations eventually made it to the European and Czech markets, so the chance is relatively high.

Would you appreciate a thermometer at home that also monitors air quality?

Sources: IThome, Gizmochina, Notebookcheck