There are three forms of insulation: reflective, resistive and capacitive.

3.1 Reflective Insulation

3.2 Resistive Insulation

3.3 Capacitive Insulation

Capacitive insulation is used to avoid immediate heat transfer by storing the heat in the building material itself. As heat enters the material, particles of capacitive insulation absorbs a certain amount of heat and provides a delaying effect for heat flow. Figure 8 shows a sequence of temperature gradients within such a wall as a time sequence, while Figure 9 shows an idealized variation of heat flow over a 24-hour cycle.

Figure 10 24-hour Heat Flow Cycle