Insulation "R" values

Are they the Total answer to insulation?

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 and in the summer high heat from roofs and walls travels from outside to inside. 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 ( R value= resistance)

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. The handle on a cast iron skillet gets hot as heat is transferred from the bottom by means of conduction.

Convection:
Convection is the transfer of heat by the movement of a fluid (water, air, etc.) Hold your hand above the stove and you feel the heat as the hot air rises by means of Conduction. Inside of a wall air removes heat from a hot exterior wall, and then circulates to the colder interior wall where it loses the heat.

Radiation: This is a direct transfer of heat from one object to another, without heating the air in between, 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 or gain, which accounts for 75% 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 isolative 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 the three ways we just discussed, conduction, convection and radiation

Choosing an insulation
The R - value is not the only consideration when choosing insulation yet it is the first thing most consumers ask, "What is the R value"

Conventional mass insulation materials like fiberglass, cellulose, rock wool and Styrofoam, no matter how thick, have almost no ability to block radiant heat energy which can account for as much as 93 percent of summer heat gain and up to 75 percent winter heat loss in conventional structures.
These products are only designed to slow down (resist) conduction heat energy only. Mass insulation once saturated with heat will simply allow remaining heat to pass through. Ever notice in the summer, its 10 PM or so and you touch one of the walls in your home that butts up to the outside, the sun has been down for hours but the wall is still Hot!
That's because the wall has been absorbing heat all day and is passing it through the wall to the inside of your home.
Remember... R-value means "resistance", if a product resists, it does not stop radiant heat transfer. R-value material only deals with conductive heat transfer. Other factors to consider when choosing insulation are the materials fire, mold, insect, vermin and moisture resistant properties, as well as its cost and ease of application.