# Heat transfer to and from your home?

So we know that we all have home heat loss. Did you know there is more than one way heat is transferred to and from your home?

There are actually three ways heat is transferred to and from your home contributing to your high energy bills.

Conduction

Conduction is heat moving through a solid object(typically) from a hot spot to a cooler spot. An example of this is if you hold one end of a piece of metal in your hand and then heat up the other end with a lighter. The end in your hand will begin to warm up. This is conduction heat transfer.

Conduction impacts home heat loss in the following ways:

> Insulation lowers conduction heat loss through walls, roofs, and foundations.

> Higher quality windows and doors lower conduction heat loss rates

> The ground around your foundation transfers heat to and from your home via conduction.

Convection

Convection is the transfer of heat from one area to an other via the movement of liquids or gases. It requires flow.

So on a winter day, air moving along your exterior walls lowers the surface temperature of these walls. Heat is then transferred via conduction from the inside surface of the wall to the exterior surface. The heat you have spent money on to warm the air in your home is transferred via convection from the warm indoor air to the inside surface of the wall.

If a temperature difference exists there is often convection heat transfer. As we know hot air rises. This is because warm air is less dense than cooler air. As warm air moves up it creates an area of low pressure that the cooler air moves to. This creates a natural flow of air.

Convection heat transfer impacts home heat loss in the following ways:

> Cooler climates require more heating

> Windy days or windy home locations increase convection heat transfer

> Indoor air movement is typically the primary heating and / or cooling method

Thermal Radiation does not require two items to be in contact with each other (unlike conduction and convection). Thermal energy is converted to electromagnetic energy (waves). It is emitted from an item at a high temperature and absorbed by a body at a lower temperature.

An example of thermal radiation is the sun warming the surface of something or someone (when you are out in the summer you can feel your skin warming up). Whenever you feel heat without touching an object or being hit with warm air, thermal radiation heat transfer is taking place. A nice warm fire or a warm baseboard heater emits thermal radiation.

Thermal Radiation impacts home heat loss in the following ways:

> Heat gain from the sun is good in the winter and not so good in the summer

> Heating and Cooling systems utilize thermal radiation

> In-floor heating systems utilize thermal radiation

> Some types of light bulbs emit more infrared radiation than visible light making them more inefficient for lighting purposes

Next Steps...

Now that we have a basic understanding of the forms of heat transfer involved in home energy systems, we might be tempted to try to obtain as close to zero heat loss as possible.

Before we work on doing this, there are a few other factors to consider, including air quality and humidity. To maintain a desired level of air quality you may have to bring fresh air into your home. If it is cold outside you will require energy to bring the temperature of this air to room temperature.