EGEE 102
Energy Conservation for Environmental Protection

Conduction Heat Loss

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Main Factors of Heat Loss

What does a house's heat loss depend on? Complete the activity below to find out the three main factors leading to heat loss.

Conduction Heat Loss Activity
Click here to open a text description of the conduction heat loss activity.

Main Factors of Heat Loss

What are the three main factors a house's heat loss depends on?

Example 1:

House A sits next to house B. Though both houses have the same basic design, house B is significantly larger than house A.

  1. Which house loses more heat?
    1. House A
    2. House B
  2. Why do you think this house loses more heat?
    1. More people in it
    2. More appliances and lights are used
    3. Larger size/more area

Example 2:

House A and house B are the exact same size and design. House A sits on the beach in a warm, tropical area, while house B sits by a ski resort in the mountains up north, surrounded by snow.

  1. Which house loses more heat?
    1. House A
    2. House B
  2. Why do you think this house loses more heat?
    1. People skiing need more heat to keep warm
    2. Snow on the roof is good insulation
    3. Outside temperature

Example 3:

House A and house B are the same size and sit next to each other. The design for both houses is the same, except house A has a thick layer of pink insulation installed. The R-value of house B is .63 and the R-value of house A is unknown.

  1. Which house loses more heat?
    1. House A
    2. House B
  2. Why do you think this house loses more heat?
    1. Less insulation
    2. It's only one color
    3. It's thicker

Answers:

Example 1:

  1. B: House B
  2. C: Larger size/more area

Example 2:

  1. B: House B
  2. C: Outside temperature

Example 3:

  1. B: House B
  2. A: Less insulation
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Most heat is lost through a house's walls through conduction. As you learned from the activity on the previous screen, the amount of heat loss depends on three factors:

  • Size of the house (area through which the heat can escape)
  • Local weather or climatic conditions:
    • The inside temperature is often constant at a comfortable temperature of 65°F.
    • As the outside temperature falls lower than 65°F, the heat is lost to the outside.
    • The higher the temperature difference, the higher the heat loss to outside.
    • By calculating the Heating Degree Days (HDD), we can determine how many degrees the mean temperature fell below 65ºF for the day.
  • Wall's capacity to resist heat loss.
    • Insulation is rated in terms of thermal resistance, called R-value, which indicates the resistance to heat flow.
    • The higher the R-value, the greater is the insulating effectiveness.