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''Insulation 101''

Understanding Insulation

Understanding insulation is really about understanding heat transfer. There are basically three types of heat transfer (sometimes referred to as heat flow). And because heat transfer is the primary cause of heat loss, it’s also the major contributor to energy inefficiencies. Every building, large or small, commercial or residential, comprises an "envelope". It’s an "envelope" constructed with materials that will directly affect the dynamics of heat transfer. That affect can be good or bad.


Conduction is heat that is transferred from one solid object to another. It’s commonly referred to as thermal conduction. For example, when a thick, cotton towel is laid over a hot radiator, the heat from the radiator will flow to the towel. By inserting an insulating layer between the two objects, heat transfer can be reduced. The reduced heat flow can be measured as a resistance factor, and with an insulation product, that factor is the R-Value - the higher the value, the better.


Convection occurs when heated air moves away from its source. A convection cycle occurs when warm air rises and cool air replaces it. The cycle is activated when temperature fluctuates; when humidity levels change; or when there is air movement. “Air infiltration” occurs when air enters or exits a building “envelope” through various openings: holes, gaps, cracks or crevices. Preventing air from infiltrating (air leakage) requires complete sealing of a space or cavity. 


Radiated heat is transmitted through space by light waves. No physical medium is required during the process of radiation. A practical example of radiated heat is a light bulb – it radiates heat as light waves and is extremely hot to the touch. To insulate against radiated heat, an “impeding” material, like an aluminum sheet, can be used to restrict and reduce heat transfer. In the insulation industry, “radiant barriers” are used to impede radiation light waves (along with heat).

Choosing the right insulation for the job

There are several criteria for choosing insulation. R-Value is probably the key consideration - it’s a measure of the insulating value in a given space. But it’s also important for insulation to inhibit air movement; to prevent moisture accumulation; to be fire resistant; and to inhibit mold and insects. Finally, it’s important to consider the cost of the insulation product and the installation. In general, choosing the right insulation should be a combination of everything above.

Insulating a space is about conserving energy, and conserving should translate into energy savings. At Great Northern Insulation, our professional installers recommend the product that best suits the job, and best addresses the type of heat transfer:

In the attic and roof we recommend Spray Polyurethane Foam Insulation (SPFI) as the ideal install, along with alternative options that combine loose-fill insulation (fiberglass or cellulose).

To inhibit air infiltration (air leakage) we use spray foam to completely seal and insulate any openings and holes in the framing “envelope” of the residential home or commercial building.

Most of the insulation products we use are designed to block the flow of radiated heat. When a cavity is totally sealed and insulated, radiant heat loss is virtually eliminated throughout.

Proudly Serving all of Southern Ontario

GTA; South Central Ontario

450 Industrial Dr.

Milton, Ontario

Canada L9T 5A6

TOLL FREE: 1-800-265-1914