A wall is heated by the sun receiving 1500 W at a given time. Calculate the heat transferred by natural convection to air at 20C for different heights of the wall: 1, 2, 3, 4, 5 meters. Similarly, calculate the power emissivity of the wall (look up emissivities for typical building materials) as well as the radiosity if the reflectivity of the wall is 0.3. Consider that the wall is opaque and the width is 4 meters.