Before determining how insulation works, we should first understand how heat is conducted. This is crucial in understanding how insulation works and what you can do to make your house more energy efficient by figuring out which part of your house requires insulation.
Heat is a form of energy. Therefore, heat cannot be destroyed but it can convert to another form of energy. With that being said, heat in a heated area can be transferred to a cool area by being absorbed by the air molecule in the cool area as a form energy transfer so that both areas will reach equilibrium. Another way of saying this is heat flows from a warmer to a cooler space just like water flows from a higher ground to a lower ground.
Why heat transfer from a heated area to a cooler area you may ask. The reason is the air molecule in the heated area has more energy compared to the air molecule in a cool area. This is the same case as water flows from high to low as water in higher ground has more energy. Therefore, heat flows from heated area to cooler area as a form of energy transfer so that both places will reach equilibrium which means both areas will have the same level of energy. When that happens, heat flow will stop.
Heat is conducted in the following ways: Convection, Conduction and Radiation. Therefore by putting a stop to these ways in which heat can transfer, you are basically insulating against the heat flow.
In your house, during winter time, the heat moves directly from all heated living spaces to the outdoors and to adjacent unheated attics, garage, basement and wherever there is a difference in temperature. On the other hand, heat transfer from outdoors to the interior of your house. To make sure your house is comfortable to live, heat lost in the winter must be replaced by your heating system and the heat gained in summer must be removed by your air-conditioner.
Therefore, in order to make your heating or cooling systems do less work which in return save your energy bills, you can put a stop or at least try to reduce the heat flow to a minimal level. And insulation is the method which can be applied to efficiently reduce the heat flow. Insulation works by giving resistance to heat flow just like you apply a resistance to water flow from higher ground to lower ground.
Insulation materials such as batts, blankets, loose fill and low-density foams all works by limiting air flow. These materials may be more familiarly referred as fiberglass, cellulose, polyicynene and expanded polystyrene. A still air is an effective insulator because it eliminates convection and reduces energy conduction to minimal level. Some foams such as polyisocyanurate, polyurethane, and extruded polystyrene, are filled with special gases that provide additional resistance to heat flow.
Please note that the ability of insulation material to limit air flow should not be confused with “air sealing”. The insulation reduces air movement only within the space it occupies. It will not reduce air movement through other cracks between building parts.
Another form of heat flow is through radiation. One way to stop the heat flow through radiation is by applying reflective insulation. Reflective insulation works by reducing the amount of energy that travels in the form of radiation. Some forms of reflective insulation also divide a space up into small regions to reduce air movement, or convection, but not to the same extent as batts, blankets, loose-fill, and foam.
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