What is the aim of insulation in walls and in roofs?
Insulation is to not let air from the outside seep in and does not let air on the inside seep out. The purpose is so in the winter, cold air does not get into the house through cracks (saves gas/oil/electricity need to heat the home) and in the summer, it does not let cold air from your AC escape unexpectedly which saves electricity to cool your home. Insulation is a great way to save money, but if you have your windows open, then it does nothing. XD Hope that helped.
Proper insulation is designed to keep you comfortable in al sorts of weather. In the winter it reduces your utility bills by keeping the cold outside where it belongs. It does the opposite in summer. It keeps the heat out. Learn all about it here.
The basic idea on insulation is to slow the movement of heat.
Insulation can reduce your heating cost. Insulating your solid walls could cut your heating costs considerably, because solid walls let through twice as much heat as cavity walls do.
Neither, it is to not let heat through.
