, Volume 33, Issue 2, pp 147–158 | Cite as

Cooling Performance and Indoor Air Quality Characteristics of an Earth Air Tunnel Cooled Building

  • D. G. Leo Samuel
  • S. M. Shiva Nagendra
  • M. P. Maiya
Original Paper


Most of the modern air-conditioned buildings have a low fresh air supply to reduce energy consumption. This results in a poor indoor air quality (IAQ) and a 30–200% higher sick building syndrome than that of a naturally ventilated building. Alternatively, energy-efficient and eco-friendly earth air tunnel system (EATS) provides a good IAQ because of the sufficient fresh air supply. This paper presents the cooling performance and IAQ characteristics of a sparsely occupied building supported with an EATS. The building was monitored for the concentration of fine and coarse particulate matter (PM), carbon dioxide (CO2) and carbon monoxide (CO), temperature distribution and relative humidity (RH) in September and October 2012. The average PM10, PM2.5 and PM1 concentrations were 6.77, 6.11 and 3.17 μg/m3 respectively when the EATS was operated. These are marginally higher compared to that when the EATS was not operated. The average indoor CO2 level, air temperature and RH were 418 ppm, 26.5 °C and 58.2% respectively when the EATS was operated. The diurnal indoor CO2 trend relates well with photosynthetic and anthropogenic activities in and around the building. The CO2 and PM concentrations correlate well with indoor air temperature and RH with a time lag.


Earth air tunnel system Geothermal cooling Indoor air quality Passive cooling Thermal comfort 

List of symbols


Indoor concentration of contaminant at any given time (m3/m3)


Initial concentration of contaminant in the room (m3/m3)


Covariance (*)


Concentration of contaminant in the supply air (m3/m3)


Expectation (*)


Number of air changes per unit time (–)


Volume of room (m3)

\( \dot{Q}_{\text{cp}} \)

Rate of volumetric contaminant generation (m3/h)


Time (h)

x, y

Variables (*)


Mean (*)


Correlation coefficient ()


Standard deviation (*)


Units vary based on the unit of variable(s)



The authors thank Indian Society of Heating Refrigerating and Air Conditioning Engineers (ISHRAE), Bangalore International Exhibition Centre and M/s. Rehau Polymers Pvt. Ltd. for their help in carrying out this study.


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Copyright information

© Metrology Society of India 2017

Authors and Affiliations

  1. 1.Refrigeration and Air-Conditioning Laboratory, Department of Mechanical EngineeringIndian Institute of Technology MadrasChennaiIndia
  2. 2.Environmental and Water Resources Engineering Laboratory, Department of Civil EngineeringIndian Institute of Technology MadrasChennaiIndia

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