Building insulation materials is used depends on a wide variety of factors. Some insulation materials have health risks, some so significant the materials are no longer allowed to be used but remain in use in some older buildings such as asbestos fibers and urea. Factors affecting the type and amount of insulation to use in a building include: Considerations regarding building and climate: Often a combination of materials is used to achieve an optimum solution and there are products which combine different types of insulation into a single form. Spray foam is a type of insulation that is sprayed in place through a
Dynamic insulation medium (m) is known. The air permeability of some materials that could be used in dynamically insulated walls or ceiling are listed in Table 3. Air permeability data is crucial to the selection of the correct material for the air control layer. Further sources of air permeability data include ASHRAE and Kumaran. Table 3: Measured Air Permeability of Building Materials (1) Pressure drop calculated at flow rate of 1 m/mh The application of the theory of dynamic insulation is best explained by way of an example. Assume a house of 100 m floor area with a dynamically insulated ceiling. Putting