Performance of earth air tunnels

Corresponding to the annual variation of the meteorological data for the year 1974 at New Delhi, a study of the annual variation of the ground temperature distribution has been carried out for different surface conditions. At a depth of around 4 m the temperature remains almost constant in all the cases; it is maximum (∼ 53°C) for a dry glazed black surface and minimum (∼ 17-3°C) for a wet shaded surface, respectively. An earth air tunnel dug at this depth provides heating/cooling to the air flowing inside it during winter/summer. We have carried out a parametric study of the performance of such tunnels in terms of the heat gain/loss by air flowing through them.