Unit C Lesson C11 Controlling the Flow of Thermal Energy
Completion requirements
Lesson C11: Controlling the Flow of Thermal Energy
Video Lesson
Why is stopping heat loss from homes important? Watch this video to learn more about how to control the flow of thermal energy in buildings.
Lesson C11: Controlling the Flow of Thermal Energy
Figure C.3.11.1– Firefighters are exposed to intense heat during fires.
Figure C.3.11.2– The suits of firefighters are made from flame-resistant fabric.
Firefighting Clothing
Often, firefighters must enter burning buildings to rescue people. For this reason, firefighters wear special suits to protect them from extreme heat and fire.
Firefighting suits and helmets are made from special heat-resistant fabrics and plastics that do not melt. Nomex™ is a type of fabric used in firefighting suits. Nomex is a thick, woven, insulating fabric that reduces heat transfer to firefighters’ bodies. This keeps them from overheating in extremely hot situations. Nomex is also flame-resistant. Nomex withstands heat and flame longer than most other fabrics do before it begins to burn, and it extinguishes quickly.
Often, firefighters must enter burning buildings to rescue people. For this reason, firefighters wear special suits to protect them from extreme heat and fire.
Firefighting suits and helmets are made from special heat-resistant fabrics and plastics that do not melt. Nomex™ is a type of fabric used in firefighting suits. Nomex is a thick, woven, insulating fabric that reduces heat transfer to firefighters’ bodies. This keeps them from overheating in extremely hot situations. Nomex is also flame-resistant. Nomex withstands heat and flame longer than most other fabrics do before it begins to burn, and it extinguishes quickly.
Reading and Materials for This Lesson:
Science in Action 7
Materials:
Science in Action 7
Reading: Pages 233–237
Materials:
2 deflated balloons, cold water, big bowl, straw, timer, thermometer, 6 small jars with lids (such as baby food jars or small canning jars), cookie sheet, hot tap water, 2 cotton socks, 4 wool socks, aluminum foil, fridge
Watch More
Nomex
Watch this video to learn more about how Nomex fabric protects people against fire.
Watch this video to learn more about how Nomex fabric protects people against fire.
Building Insulation
Insulation in the walls of buildings keeps structures warm in cold weather and cool in hot weather. Using insulation to prevent heat transfer helps people use less energy to heat and cool buildings.
Over time, humans have used many different insulation materials. For example, traditional adobe buildings in warm, dry climates around the world were made from bricks made of mud and straw. Thick adobe walls are good insulators. Adobe houses stay cool on hot days, and they stay warm on cool days.
In pioneer days, especially in western Canada, some homes were built of strips of sod; others were of logs fitted to reduce cracks. Both materials provided insulation, especially against the cold of winter.
Insulation in the walls of buildings keeps structures warm in cold weather and cool in hot weather. Using insulation to prevent heat transfer helps people use less energy to heat and cool buildings.
Over time, humans have used many different insulation materials. For example, traditional adobe buildings in warm, dry climates around the world were made from bricks made of mud and straw. Thick adobe walls are good insulators. Adobe houses stay cool on hot days, and they stay warm on cool days.
In pioneer days, especially in western Canada, some homes were built of strips of sod; others were of logs fitted to reduce cracks. Both materials provided insulation, especially against the cold of winter.
Asbestos is an insulating material that was discovered in ancient times. It is a mineral found in some rocks. The asbestos mineral is made of very small crystal fibres. These fibres trap air, which makes asbestos a good insulator. Asbestos is also fire-resistant,
which made it useful as building insulation. However, we have learned that asbestos fibres cause negative health effects such as cancer if they are inhaled. For this reason, asbestos is no longer used as insulation in many countries. In fact, removing
asbestos materials from old buildings requires careful hazardous goods procedures.
The most common type of insulation used in modern buildings, including homes, is fibreglass. Fibreglass is made from thin strands of glass spun together into thick batts that fit within the cavities between the wooden supports in walls, for example. Glass is an effective thermal insulator, and the fibre structure traps air as an additional insulator. A caution: Do not touch fibreglass with your bare hands because it contains tiny slivers of glass that can cause itching or can hurt you.
The most common type of insulation used in modern buildings, including homes, is fibreglass. Fibreglass is made from thin strands of glass spun together into thick batts that fit within the cavities between the wooden supports in walls, for example. Glass is an effective thermal insulator, and the fibre structure traps air as an additional insulator. A caution: Do not touch fibreglass with your bare hands because it contains tiny slivers of glass that can cause itching or can hurt you.
Figure C.3.11.3– Adobe homes are cool in hot weather.
Figure C.3.11.4– Fibreglass insulation is made from tiny glass fibres.
Figure C.3.11.5– Asbestos was used as an insulation material, but it has caused health problems.
Watch More
Building Insulation
Why is asbestos so harmful to people? Watch this video to learn more.
Why is asbestos so harmful to people? Watch this video to learn more.
Often, heat is lost through the attics of homes. Watch this video to see how various kinds of insulation are used to insulate attics.
This video shows how adobe or cob houses are built.
Try It!
Insulating Air
Try this simple experiment to observe how air acts as an insulator.
Materials:
-
2 deflated balloons
- cold water
- big bowl
- straw
-
timer
Instructions:
-
Fill the bowl with cold water.
-
Stretch one balloon tightly over each of your index fingers.
-
Slide the straw into one of the balloons.
-
With your mouth, blow some air into the straw so the balloon inflates slightly around your finger.
-
Quickly remove the straw so the balloon stays full of air.
-
Start the timer.
-
Put both of your balloon-covered fingers into the bowl of cold water.
-
Start the timer. After 2 minutes, remove your fingers from the cold water. Which finger feels colder?
Questions:
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
The air acted as an insulator around your finger. Air is an insulator because the particles in air are spread far apart and do not conduct heat quickly.
Heat conducted quickly from the non-insulated finger to the cold water. As a result, the non-insulated finger felt cold faster.
Heat conducted slowly from the air-insulated finger to the cold water. As a result, the air-insulated finger felt warmer for longer.
Heat conducted quickly from the non-insulated finger to the cold water. As a result, the non-insulated finger felt cold faster.
Heat conducted slowly from the air-insulated finger to the cold water. As a result, the air-insulated finger felt warmer for longer.
Lesson Activity
Testing Insulators
Which materials are best at preventing heat loss? Try this experiment to test various insulators that people wear on their feet.
Materials:
Which materials are best at preventing heat loss? Try this experiment to test various insulators that people wear on their feet.
Materials:
- thermometer
- 6 small jars with lids (such as baby food jars or small canning jars)
- cookie sheet
- hot tap water
- 2 cotton socks
- 4 wool socks
- aluminum foil
- fridge
-
timer
Download:
DOWNLOAD this document. It provides a space for you to write answers to questions later in this activity. It also provides a chart for you to record your observations.
Instructions:
DOWNLOAD this document. It provides a space for you to write answers to questions later in this activity. It also provides a chart for you to record your observations.
Instructions:
-
Clear a space in the refrigerator large enough to fit the cookie sheet loaded with jars.
-
Place the jars on a cookie sheet.
-
Place the thermometer under running hot tap water to measure the temperature of the water. Record this temperature on the Observations Chart as “Initial Temperature” for every jar.
-
Fill all the jars with hot tap water and close their lids quickly.
-
Place each of the six jars quickly into one of the following insulators:
- 1 cotton sock
-
1 cotton sock wrapped in aluminum foil
- 1 wool sock
- 2 wool socks
-
1 wool sock wrapped in aluminum foil
-
Leave one jar with no insulation.
-
Put the cookie sheet with the jars into the fridge for 15 minutes.
-
After 15 minutes, remove the cookie sheet from the fridge.
-
Remove one jar from an insulator and open the jar’s lid. With the thermometer, measure the temperature of the water in the jar. Record the temperature for the correct insulator on the Observations Chart under “Final Temperature”.
-
Repeat Step 8 for the remaining five jars.
-
The change in temperature equals the initial temperature minus the final temperature. Calculate and record the change in temperature for all the insulators.
Observations:
Record your observations in a chart like this:
Record your observations in a chart like this:
Questions:
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
Think about the following questions very carefully. Then, type or write your answers. After you have your answers, click the questions for feedback.
The jar with no insulation experienced the greatest change in temperature. This indicates that glass on its own has less insulating quality than wool or cotton has.
The results of this experiment will vary depending on the size of the socks and other factors. Most often, the jar with two wool socks will show the least change in temperature. This indicates that wool layers insulate very well.
The socks wrapped in shiny aluminum foil reflected heat radiation back into the jar, which kept the jar warmer.
Foil is used to cover winter boot insoles because it reflects body heat radiation back towards the foot.
This experiment shows that wool sock layers and foil boot insoles help keep heat near the feet for longer periods. Think about how to keep your feet warmer on cold winter days when you choose new boots.
Cold Weather Clothing
Warm winter clothing is a necessity for Canadians. Cold weather clothing is designed to trap layers of insulating air close to the body.
Most First Nations traditional winter clothing incorporates animal fur. Fur is a good insulator because it traps pockets of air between the little strands of fur. Plains First Nations tanned bison and deer hides for clothing. In summer, they wore clothing made from hides stripped of fur. For winter clothing, they used hides with fur because the fur provided extra insulation.
The Inuit of Northern Canada need very warm clothing. Traditional Inuit winter clothing includes parkas made from layers of caribou hide. Layered materials trap insulating air between the layers. Inuit parkas have fur-trimmed hoods that trap warm air around the person’s exposed face. The Inuit wear multiple layers on their feet, also. They wear fur slippers inside waterproof sealskin boots.
Most First Nations traditional winter clothing incorporates animal fur. Fur is a good insulator because it traps pockets of air between the little strands of fur. Plains First Nations tanned bison and deer hides for clothing. In summer, they wore clothing made from hides stripped of fur. For winter clothing, they used hides with fur because the fur provided extra insulation.
The Inuit of Northern Canada need very warm clothing. Traditional Inuit winter clothing includes parkas made from layers of caribou hide. Layered materials trap insulating air between the layers. Inuit parkas have fur-trimmed hoods that trap warm air around the person’s exposed face. The Inuit wear multiple layers on their feet, also. They wear fur slippers inside waterproof sealskin boots.
Figure C.3.11.6– Traditional Inuit clothing is made from animal hides and fur.
Figure C.3.11.7– Goose or duck down (inner feathers) are used as insulation in jackets and sleeping bags.
Figure C.3.11.8– Winter jackets insulate people from cold outdoor temperatures.
Cold Weather Clothing
Today, most Canadians wear winter jackets made from lightweight fabric and insulating layers. Sometimes, the insulating layer is a fluffy filler fabric that traps air. Sometimes, coats are filled with down, which is fluffy duck or goose inner feathers. Feathers are good insulators because pockets of air are trapped between the fibres of the feathers.
Outdoor winter activities such as skiing, skating, and tobogganing are lots of fun. If you spend time outdoors in the winter, you should wear warm insulating clothing to prevent hypothermia and frostbite.
Make sure you have understood everything in this lesson. Use the Self-Check below, and the Self-Check & Lesson Review Tips to guide your learning.
Unit C Lesson 11 Self-Check
Instructions
Complete the following 6 steps.
Don't skip steps – if you do them in order, you will confirm your
understanding of this lesson and create a study bank for the future.
- DOWNLOAD the self-check quiz by clicking here.
- ANSWER all the questions on the downloaded quiz in the spaces provided. Think carefully before typing your answers. Review this lesson if you need to. Save your quiz when you are done.
- COMPARE your answers with the suggested "Self-Check Quiz Answers" below. WAIT! You didn't skip step 2, did you? It's very important to carefully write out your own answers before checking the suggested answers.
-
REVISE your quiz answers if you need to. If you answered all the questions correctly, you can skip this step. Revise means to change, fix, and add extra notes if you need to. This quiz is NOT FOR MARKS, so it is perfectly OK to correct
any mistakes you made. This will make your self-check quiz an excellent study tool you can use later.
- SAVE your quiz to a folder on your computer, or to your Private Files. That way you will know where it is for later studying.
- CHECK with your teacher if you need to. If after completing all these steps you are still not sure about the questions or your answers, you should ask for more feedback from your teacher. To do this, post in the Course Questions Forum, or send your teacher an email. In either case, attach your completed quiz and ask; "Can you look at this quiz and give me some feedback please?" They will be happy to help you!
Self-Check Time!
|
Self-Check Quiz Answers
Click each of the suggested answers below, and carefully compare your answers to the suggested answers.
If you have not done the quiz yet – STOP – and go back to step 1 above. Do not look at the answers without first trying the questions.
Closing window shutters decreases heat transfer into a house by radiation from the Sun. This keeps a house cooler on hot summer days.
A thermogram enables a person to determine the specific locations where heat is lost from the house to the cooler outdoors. Then, the person can add insulation or sealant to those locations to prevent heat transfer. This reduces energy waste
and heating costs.
Storm doors trap a layer of air between the storm door and the main door. This layer of air acts as insulation.
Weatherstripping seals the cracks between a door and a door frame. This prevents warm air from escaping from a house to the cold outdoor atmosphere.
Layers of clothing trap air between the layers. Air is a good insulator and prevents heat transfer away from your body.