Insulation 101

Understanding Heat Transfers and Insulation

Energy efficiency of any structure is defined by its ability to control the three basic types of heat flow. These modes of heat transfer vary in importance and magnitude for any structure depending upon the materials used and workmanship employed to construct the building "envelope".

Basically heat is transferred in three ways:

• CONDUCTION
• CONVECTION
• RADIATION

CONDUCTION is the transfer of heat through solid portions of a structure. The transfer of heat conduction can be significantly reduced by using insulation. Insulation is a material with low thermal conductivity which thereby resists the flow of heat. This thermal resistance or Rvalue is a uni-directional measurement of this type of heat flow. The higher the R-value, the greater the insulating value.

CONVECTION is the transfer of heat through the movement of air caused by differences in pressure. This can happen because of temperature or humidity differences, wind or mechanical air movement. The term air infiltration, or air leakage, refers to air that enters the structure through gaps and cracks in the building envelope.

RADIATION is the transfer of heat by light waves that generate heat upon contact with any material capable of converting the radiation to heat and then releasing this heat as radiation to the air or conducting the heat to adjacent material. Radiation impeding materials, or 'radiant barriers', such as aluminum foil block the radiation light waves and greatly reduce the heat generation.

Choosing the Right Insulation

When choosing insulation, R-value is not the only thing to consider. Other factors include the material’s fire, mold, insect and moisture resistant properties, its ability to control or withstand air leakage, as well as its cost. At Great Northern Insulation, we install products to address all of these types of heat transfer:

CONDUCTION - We install loosefill insulation or fiberglass batts in the attic, fiberglass batts or spray applied polyurethane foams in the walls and fiberglass batts or polyurethane foams in the floors.

AIR LEAKAGE - Great Northern Insulation uses foam insulations or sealants to seal the holes, crevices and penetrations in the exterior framing envelope of the house. We also install sprayed-in-place polyurethane foam air barriers for commercial and industrial applications.

RADIATION - Most insulations which Great Northern Insulation installs have a cellular structure which blocks the flow of heat of radiation. If the cavity is completely filled with insulation, the radiant heat loss from the inside finish to the outside sheathing is virtually eliminated.