 Introduction To Insulation
And Heat Flow
(This is an important point) Heat naturally flows from warm areas to cooler areas, regardless of direction. In winter, heat flows from the inside of a building to the outside. This flow of heat can never be stopped completely, but the rate at which it flows can be reduced by using materials which have a high resistance to heat flow.
Heat is transferred
in three distinct ways,
any or all of which may
be occurring at any given time!
Conduction - Conduction is the transfer of heat through a solid object. When one part of an object is heated, the molecules within it begin to move faster and more vigorously, when these molecules hit other molecules within the object they cause heat to be transferred through the entire object.
Convection - Convection is the transfer of heat by the movement of a fluid (water,air, etc.) Inside of a wall cavity, air removes heat from a warm interior wall, then circulates to the colder exterior wall where it loses the heat.
Radiation - Any object will radiate heat to cooler objects around it by giving off "heat waves". This is a direct transfer of heat from one object to another, without heating the air in between. This is the same process in which the Earth receives heat from the Sun or a wood stove supplies heat to its surroundings.
Obviously an important step in the creation of an energy efficient house or building is to control heat loss, which accounts for 70% of the total energy loss of a home. As was previously stated, heat will flow in any direction where a temperature difference occurs. Therefore all areas which separate the interior of a house or building from the outside or which separate heated spaces from unheated (or air conditioned) spaces need to have a high resistance to heat flow, in other words, they should be insulated!
How does insulation work?
Insulation is any material that slows the rate of heat flow from a warm area to a cooler one. The more the rate is slowed, the better the insulative qualities of the material. Its ability to resist heat flow is measured as an R or RSI (metric) value, the higher the R - value, the more the material will resist the flow of heat. In order to be effective, insulation materials must be able to reduce the transfer of heat by conduction, convection and radiation, this is determined by both its physical properties and installation.
Conduction - Since conduction is the transfer of heat through solid objects, most insulations contain tiny "pockets" of air. These air pockets reduce the conductive heat loss by minimizing the amount of "solid" material within a wall or ceiling.
Convection - In large air spaces, such as a wall cavity, large amounts of heat can be lost through convection (and radiation) As long as the insulation is carefully installed to completely fill the cavity, there should be no air spaces in which convective heat loss can occur.
Radiation - Most insulation has a cellular structure which blocks the flow of heat by radiation. If the cavity is completely filled with insulation, radiant heat loss through the walls or ceilings is reduced.
Choosing an insulation:
The R - value is not the only consideration when choosing insulation, other factors which deserve consideration are the materials fire, mold, insect, vermin and moisture resistant properties, as well as its cost and ease of application. We think you'll agree, Insuladd fits the bill.
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