Your walls are too exposed to direct sun.
The walls get heated up during the day. The heat stored is radiated out at night.

You need to block off the direct sunlight by shielding the walls. You can consider:

1.  tree planting or creepers. These would take time to grow of course.
2. additional layer of wall with air cavity in between. The additional layer can be of weatherboard, metal sheet or louvres or bricks . A reflective foil in between would help to insulate the wall further.
3. Extending the roof cover or shade over the walls.
4. For windows, installing heat-reflective film like you do for cars would help a lot. The number of windows should be kept to a minimum.

With radiant heat from the walls, you'd feel it even with the air conditiioning is  switched on.



This post has been edited by tehtmc: Jan 23 2012, 11:35 PM