Keeping the HEAT in: Experiment to test insulation materials
See the comment below for an explanation of the experiment
9 comments:
Anonymous
said...
We made one wall of each component, wood, dirt, cellulose and aluminum. We put 4 wood slats around the edges of a bag and marked the square in the middle. We filled the square with dirt/cellulose and stapled around it so that it wouldn't move. Then we taped the 4 wooden slats into place and made sure they were secure by adding even more tape. To make the wood wall, we simply taped 4 or 5 wooden slats together. For the aluminum wall, we taped 4 slats in a square and then taped the aluminum into place. With the walls made, we put them around a lamp and taped them into place. We put a thick piece of wood over the top as the roof. We turned on the lamp and found that we could see many holes the air could escape through and filled them as much as we could with yarn, paper towels and clothes. We set the timer for 10 minutes and played with slinkys until it was up. Then we held a thermometer inside to get the inside (lamp) temerature. Then we held thermometer against the outside of each wall and recorded the results. Inside (lamp) Temperature: 41ºC Room Temperature: 22ºC Outside surface of Wood: 29ºC Outside surface of Aluminum: 30ºC Outside surface of Cellulose: 31ºC Outside surface of Dirt: 26ºC
Dirt (or soil as we call it) was an excellent insulator in your experiment. Your experimental details together with the pictures on the blog gave me all the information I needed to repeat your experiment. I got the same results (give or take 1C). Can you explain your results? What do you think it is about the soil that is making it work so well as an insulator? I found the results surprising especially since alot of people have cellulose insulating their homes while not many have soil. Dr. B.
We think soil was such a good insulator because it's moist and thick. The water takes a long time to heat/cool, keeping the temperature inside about the same. Cellulose is an outdated method and will not work as well because it is dry and light and will not work if not packed thickly.
Of course,how silly of me, I should have thought of the moisture content of soil immediately. You know I was just looking up the Specific Heat Capacity (measured in joules/(kg.C)) of some of the materials you tested. Aluminum 900, Water 4180, Wood 1700. You are absolutely right - water has the highest Specific Heat Capacity of the three, meaning it takes more Heat Energy to heat up water than it does to heat up Aluminum or Wood (and I guess since cellulose is finely shedded newspaper it would have a Specific Heat Capacity similar to Wood perhaps. Dr. B.
Dr B. I think there is a very good reason why people do not use moist soil for insulation - think about it - mold, bacterial growth, rotting timbers....I know you are not a biologist but try to be a little more practical g.i. Brunel
Sorry G.I. Heat team A You know I've been thinking...are we sure that moisture is necessary? I mean we didn't test dry soil...what to you think? You developed a very well educated guess about the moisture and I am ready to bet my bottom dollar that you're right but maybe you should test that hypothesis and do the comparison - use that great experimental set up you built and compare moist and dry soil..Let me know what happens Dr B.
Dr. B, We tried the experiment again, except this time instead of just a soil wall, we made sure the soil was dry. The room temperature was 25ºC, the "house" temperature was 35ºC and the dry soil wall was 26ºC. As you can see, the temperature inside the "house" dropped by 6ºC, we think that is because the first time we left the light on for a few more minutes than we did this time. Dr. Rees is doing the experiment a second time, excpet leaving the light on for those extra precious minutes we didn't. Heat Team A
Dry soil performed better as an insulaton than wet soil.
We were surprised by this result at first but then we noticed that the dry soil was thicker than the wet soil, so the distance the heat travelled trough was greater for the dry soil.
This blog was created as a site for interaction between the virtual people in the game HEAT and the participants who role-play as scientist in the game. Each team consists of a physicist, an engineer and an environmental scientist. Teams are competing for the contract to design housing for a city in 2020 reducing energy costs is the new imperative. Teams interact with a wider virtual team. On the first posts you can read their bios.
See the comment below for an explanation of the experiment
9 comments:
We made one wall of each component, wood, dirt, cellulose and aluminum. We put 4 wood slats around the edges of a bag and marked the square in the middle. We filled the square with dirt/cellulose and stapled around it so that it wouldn't move. Then we taped the 4 wooden slats into place and made sure they were secure by adding even more tape. To make the wood wall, we simply taped 4 or 5 wooden slats together. For the aluminum wall, we taped 4 slats in a square and then taped the aluminum into place. With the walls made, we put them around a lamp and taped them into place. We put a thick piece of wood over the top as the roof. We turned on the lamp and found that we could see many holes the air could escape through and filled them as much as we could with yarn, paper towels and clothes. We set the timer for 10 minutes and played with slinkys until it was up. Then we held a thermometer inside to get the inside (lamp) temerature. Then we held thermometer against the outside of each wall and recorded the results. Inside (lamp) Temperature: 41ºC
Room Temperature: 22ºC
Outside surface of Wood: 29ºC
Outside surface of Aluminum: 30ºC
Outside surface of Cellulose: 31ºC
Outside surface of Dirt: 26ºC
Dirt (or soil as we call it) was an excellent insulator in your experiment. Your experimental details together with the pictures on the blog gave me all the information I needed to repeat your experiment. I got the same results (give or take 1C). Can you explain your results? What do you think it is about the soil that is making it work so well as an insulator? I found the results surprising especially since alot of people have cellulose insulating their homes while not many have soil.
Dr. B.
We think soil was such a good insulator because it's moist and thick. The water takes a long time to heat/cool, keeping the temperature inside about the same. Cellulose is an outdated method and will not work as well because it is dry and light and will not work if not packed thickly.
Of course,how silly of me, I should have thought of the moisture content of soil immediately. You know I was just looking up the Specific Heat Capacity (measured in joules/(kg.C)) of some of the materials you tested. Aluminum 900, Water 4180, Wood 1700. You are absolutely right - water has the highest Specific Heat Capacity of the three, meaning it takes more Heat Energy to heat up water than it does to heat up Aluminum or Wood (and I guess since cellulose is finely shedded newspaper it would have a Specific Heat Capacity similar to Wood perhaps.
Dr. B.
Dr B.
I think there is a very good reason why people do not use moist soil for insulation - think about it - mold, bacterial growth, rotting timbers....I know you are not a biologist but try to be a little more practical
g.i. Brunel
Sorry G.I.
Heat team A
You know I've been thinking...are we sure that moisture is necessary? I mean we didn't test dry soil...what to you think? You developed a very well educated guess about the moisture and I am ready to bet my bottom dollar that you're right but maybe you should test that hypothesis and do the comparison - use that great experimental set up you built and compare moist and dry soil..Let me know what happens
Dr B.
Dr.B
thanks for your imput we will do the experiment again and we will try dry soil. Any other productive ideas people have would help us immensly.
Dr. B,
We tried the experiment again, except this time instead of just a soil wall, we made sure the soil was dry. The room temperature was 25ºC, the "house" temperature was 35ºC and the dry soil wall was 26ºC. As you can see, the temperature inside the "house" dropped by 6ºC, we think that is because the first time we left the light on for a few more minutes than we did this time. Dr. Rees is doing the experiment a second time, excpet leaving the light on for those extra precious minutes we didn't.
Heat Team A
I tried this experiment again and got the following results
Inside temperature 45C
Outside dry soil temp. 29C
Outside wet soil temp. 32C
Dry soil performed better as an insulaton than wet soil.
We were surprised by this result at first but then we noticed that the dry soil was thicker than the wet soil, so the distance the heat travelled trough was greater for the dry soil.
Dr Rees and the upper elementary class
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