Bottom Line on a Warm Home
Bottom Line: What Keeps Your Home Warm
In The Winter and Cool In The Summer?
By Kimberly Brumbaugh
Director of Marketing
Access Energy Cooperative
Heat Transfer! Heat is always trying to move from a warmer body to a cooler body until an overall equal temperature is established between the two bodies. There are three different ways heat moves including: conduction, convection and radiation. Controlling heat transfer will help your home feel warmer in the winter and cooler in the summer.
Conduction
This form of heat transfer is by direct physical contact. A good example is heating a pan by placing it on a stove. Heat moves from the cooking unit to the pan by direct contact. In your home, the difference in temperature between the inside and outside air will force conduction heat transfer through your building shell (walls, ceilings and floors).
In order to reduce the conduction of heat energy through the building envelope, the thermal resistance of the building can be increased. Resistance, commonly referred to as the R-Value, is a measure of the ability of the materials to reduce heat flow or insulate the shell. The higher the R-Value, the more resistance to the flow of heat through the building shell. The most important tool to increase resistance in a building is to add insulation.
Convection
This form of heat transfer is by air currents. A furnace blowing warm air into a room is an example of convection. Convection can occur in your home in each room intentionally or unintentionally through openings that allow air to move in and out of the building. This type of air movement is called infiltration. Air that is infiltrated must be heated or cooled to the room temperature or it will change the temperature of the room/building, causing a direct relationship between heating and cooling costs and average outside temperatures.
Common places of infiltration include cracks around windows, doors, utility entry points, electrical outlet gaskets, exhaust fans, sill plates and rim joists, among many other places. An effective method to determine air leakage is with a blower door test.
In order to cease infiltration, openings that allow the air movement in and out of the building need to be revealed and closed. Common infiltration controls include weather-stripping, caulking, gaskets on outlets and wall switches, glass doors on fireplaces, and door sweeps.
Radiation
This form of heat transfer is accomplished by heat radiation (rays). Heat from the sun or the fireplace is a good example of radiation. This type of heat transfer occurs in "line of sight." Radiation needs no air to heat things since it will warm objects in a vacuum. In your home, the sun transmits heat radiation through the windows and other glass areas.
Windows can allow heat loss or gain through all three types of heat transfer. Conduction is impacted by the insulation properties of the glass, infiltration is determined by the air leakage around the window, and solar heat gain is impacted by the ability of the window to reflect radiation. Factors that can influence heat transfer through a window include window orientation, latitude, time of day and year, type of glass, landscaping and shading devices.
To find out how well your home handles heat transfer and how prepared it is to withstand the cold temperatures this winter, Access Energy Cooperative will conduct a free energy audit of your building, including a blower door test. We will then help you determine what action you can take to make your home warmer this winter, and cooler next summer. Call us today to set up an appointment.