Façade-Level Monitoring of CO2 Variability under Urban Heat Island Conditions using Low-Cost Sensor Data Loggers

Area of Science:

• Environmental Science
• Urban Planning
• Building Science

Background:

• Urbanization and land-use changes exacerbate the urban heat island effect (UHIE).
• Microclimatic shifts impact thermal comfort, air quality, and indoor ventilation.
• Existing monitoring methods lack façade-level resolution for building-specific interventions.

Purpose of the Study:

• To present a reproducible, low-cost protocol for façade-specific monitoring of microclimatic parameters.
• To assess diurnal variations in CO2, temperature, and humidity on contrasting building façades.
• To validate the protocol across diverse urban forms in Indian cities.

Main Methods:

• Deployment of non-dispersive infrared (NDIR) sensors integrated with microcontroller data loggers on sun-exposed and shaded façades.
• 24-hour monitoring cycles capturing diurnal variations.
• Calibration against outdoor baseline CO2 concentrations for accuracy.

Main Results:

• Consistently higher CO2 concentrations were observed in densely built zones compared to green façades (19-78 ppm difference).
• Localized temperature increases of up to 2 °C and reduced relative humidity were associated with higher CO2.
• UHIE was confirmed to contribute to pollutant retention at the façade level.

Conclusions:

• The proposed protocol offers a scalable, field-friendly approach for urban microclimate assessment.
• This method supports HVAC optimization, environmental health research, and sustainable building design.
• The framework can be extended to monitor additional air quality parameters for comprehensive urban assessment.