Hello techie,

There are several methods by which you can insulate you home against both heat and cold e.g blankets, boards, foam etc.

The most economical of them in my opinion is boards. They are usually made of Polystyrene or a similar material. The biggest advantage that they have is the flexibility to install them even after the house is fully built. They do require an additional coating of cement after they are put in place but that is a far better option than to strip and hollow the walls for certain other types of insulation. These boards are usually installed on the outside of the structure so they are the least bothersome. Do shop around though. Everyone has his own preference.