How It Works

How Heat is Transferred

Heat is transferred from one source to another via three methods of transfer: conduction, convection, and radiation.

Conductive: the transfer of heat flowing through a substance (molecular motion) or to another touching substance. If you touch a pot on the stove, the heat is transferred from the pot to your hand via conductive heat transfer.

Convective: the transfer of heat in fluids, such as rising heated air, steam, and moisture. If you put your hand above a boiling pot, you will feel heat rising from the pot in the form of steam. This transfer of heat from the pot upwards is via convective heat transfer. Convective heat transfer results in warmer air rising and cooler air settling creating a convection loop termed free convection. A Convection loop can also be generated mechanically with the aid of fan or wind and is then called forced convection.

Radiant: the transfer of heat via infrared radiation rays that are invisible to the naked eye and unaffected by air currents. If you step outside on a windy sunny day, you will feel the sun’s heat rays on your face. This transfer of heat from a heated source across an air space to a colder surface is via radiant heat transfer. All materials radiate radiant heat in ranges from 0% to 100%. This energy cannot be destroyed, only reflected or absorbed. Radiant heat accounts for 93% of heat gain in the summer and 50% to 75% of heat loss in the winter.

Some common examples of radiant heat transfer:

• Skin warming up on a sunny day via the radiant heat from the sun regardless of the ambient temperature.
• Roof shingles heated via the radiant heat from the sun.
• Heat radiating from a light bulb.

The following series of graphs demonstrate how heat is transferred in all directions:

Conventional Insulation

 

Most people are familiar with traditional insulating materials such as fiberglass, cellulose, styrofoam, and rock wool. These products absorb or slow down convective and conductive heat transfers. These types of insulation do not BLOCK heat – only slow it down. Therefore, after a period of time, 100% of the heat absorbed would eventually transfer through the insulation. The rate in which this heat eventually transfers through an insulation material is the material’s R-Value.

Fiberglass and blown-in cellulose insulation rely on air spaces within the material to decrease the conductivity of heat. They also reduce convective heat flows by trapping heating air flows and thereby restricting air circulation.

The Enersave Reflective Barrier works by reflecting up to 97% of heat energy back in the direction of its source, and the true performance is not measured by the R-Value but rather by its ability to redirect heat energy.

The following diagram illustrates the amazing heat reflecting power of Enersave’s highly reflective radiant barrier.  Using BTU’s (British Thermal Unit) as the true measure of heat loss, the following diagram clearly indicates that without any insulation at all and using three separate Enersave reflective barriers with a small airspace between each, the total BTU’s dropped from 319 BTU’s in the uninsulated wall in case 1 to 48 BTU’s in case 3.