I will investigate the effectiveness of different types of insulation in different parts of the home. For floor insulation I will use a foam sheet, about 1cm thick. This will be a good insulator because it has a lot of air bubbles. These air bubbles contain air that is at room temperature so when a beaker of hot water is place on it the air inside the foam will take the heat and store it there, close to the beaker so it will, theoretically cool less quickly. I will use the same foam to simulate the loft insulation but it will be on to of the beaker, acting as a lid as well as a form of insulation. Because it is acting as a lid as well it will also reduce the effects of evaporation, so it should cool even slower. To simulate cavity wall insulation I will put a piece of carpet tile wrapped around the side of the beaker. This should also be a good insulator because it has a carpet “pile” which is the fibres that stick up out of the carpet. Because these stick up and are generally loop shaped they will trap air like the foam and simulate cavity wall insulation well. Double glazing will be the most difficult form of insulation to imitate. I will put the same size beaker that
I am using for the rest of my experiments in a larger beaker with pieces of card at the place where the tops of the beakers join to stop the smaller one dropping inside the larger one. This will create an empty air space which does reasonably simulate double glazing but has air in it (whereas double glazing has gas) and is at normal room pressure (whereas in double glazing it is at a very low pressure to prevent air being convected, conducted and radiated as easily). I will also complete a control experiment which I will be able to compare the rest of my results to.
Prediction
I predict that the loft insulation simulation will work best because it will prevent convection and evaporation of thermal energy out of the top of the beaker as a result of the foam sheet over the top of it. Also, around 25% of the energy that is lost from our homes is lost through the roof and even though 35% is lost through the walls, evaporation of thermal energy doesn’t occur much in the home because there is typically only air involved and not a liquid.
The insulation method that I think will be second best is double glazing. This is because the air space between the small beaker and the large beaker will take up the thermal energy from the small beaker because the air will be cooler than the liquid in the small beaker. Thus, the thermal energy from the water will not totally dissipate into its surroundings but stay close to the source so it will stay warmer for longer.
Next I think it will be wall insulation because this is a larger surface area the floor insulation and it will cover the higher areas of the beaker where the hotter particles will have convected up to. The carpet tile that will be used to simulate the wall insulation will be appropriate because, like the foam, it traps small pockets of air and when this air is heated up by the water it stay there instead of going into the atmosphere. So, like the other three methods the warm air stays close to the water therefore keeping it warmer for longer. Also, around 35% of the energy lost from the home is lost through the walls.
The worst insulation, I believe, will be floor insulation because the majority of the hot particles from the liquid are convected to the top of the beaker and out into the atmosphere. So, all that the foam floor insulation will be near is the cooler water particles at the bottom of the beaker. Also, only about 15% of the energy that is lost from our homes is lost through the floor.
Obviously the control experiment should be the worst because it has no insulation at all.
Apparatus
I will use the following apparatus:-
- Beaker
- Boiling Water
- Kettle
- Thermometer
- Card
- Carpet tile
- Foam
- Stop clock
Method
I will first set up all of the apparatus shown in the preceding diagrams. I will then boil the kettle and pour the water in the beaker being aware of the safety that is involved with boiling water. I will make sure that the kettle and the beakers of boiling water are in the middle of the table and not on the edge where they can be easily knocked off; it would also be a good idea to have a sign or some sort of notification that boiling water is being used so people will be more careful around it. I will use 200cm3 of water; this will be measured using the scale on the side of the beaker. I will start the clock when the temperature drops to 85oc so this way, if any of the water is below what it should be it won’t matter because I will have to wait for all if the experiments to cool to 85oc (this way it will be a fair test). When the clock is started I will take the temperature of each experiment individually at one minute intervals for ten minutes. To try to increase the accuracy of the investigation I will repeat each experiment so I have two results, I will then find the average of these results so they will be more accurate and there will be less anomalous results shown on my graphs. I will record my results in a table (shown below :-).
Results
First results
Second results
Average of the two sets of data
Conclusion
I conclude that my first hypothesis was mostly correct. The floor insulation and wall insulation experiments were opposite ways around to what I predicted but this could have been because of errors on the experiment. My graph clearly shows that loft insulation was the best because it is at the top of the graph and stays there until the last reading. My graph also shows that the control experiment was the worst performing experiment of them all
My experiments have shown the value of insulation in every day life in the home and how much energy it can save. The most effective form of insulation is loft insulation; this is also probably one of the most cost-effective insulation types because it is relatively cheap to buy and install, unlike something like double glazing which is very expensive. Loft insulation is more effective than any other because it stops the loss of thermal energy through convection and evaporation from the top of the beaker. This would have the same insulating effect in a house because the majority of the heat from the home is convected into the loft and out of the roof; but, if it can not get into the loft the energy can not be lost through the roof.
The next most effective form of insulation was double glazing. Although this was one of the most effective forms of insulation it is probably the worst for cost-effectiveness. This is because it is very expensive to buy and install so save a relatively tiny amount on your heating bill. This was a good insulator because the thermal energy was transferred to the air between the two beakers and stayed there close to the water so it was kept warmer for longer. Water was able to convect to the top of the beaker and evaporate out in this experiment so this would be one of the major factors in its cooling.
The second worst type of insulation was floor insulation. This was because it is only at the bottom of the beaker where the cold water particles are, due to the fact that the hot water particles have convected to the top and been replaced at the bottom by cooler, denser particles. Floor insulation is relatively cheap to install but is not that effective at insulating, so it is about average effectiveness and about average cost-effectives.
The worst type of insulation was the simulation of wall insulation. This was probably because of an error in the experiment because I would expect is to be better than the floor insulation because it is insulating the sides at the top of the beaker where all of the warm water particle are; whereas the floor insulation is only insulating the cooler particles at the bottom of the beaker. Although this too is relatively cheap to have done it does not save you a lot of money so it is not effective or cost-effective.
The control experiment went as planned and was the worst insulator because it has no insulation and only a glass beaker to surround it. Although glass does not conduct or radiate heat well all of the other experiments had insulation as well as the glass so were all better.
Evaluation
On my graphs there are a few anomalous results which could have occurred because of a number of errors in my experiments. The graphs are mostly curved lines so they are called the thermal energy curve. There are far less errors on the average graph than the other two so this proves that repeats increase accuracy.
Initially the two experiments, floor insulation and wall insulation are opposite ways round to which I predicted. The floor insulation overall, was actually better than the wall insulation. I predicted this because the majority of the warm water particles inside the beaker will be convected to the top of the beaker; and the wall insulation would be covering the sides of the beaker at the top whereas the floor insulation would be covering up the bottom of the beaker, where only the cooler particles would be, due to convection. This incongruity may have occurred because different materials were used for the wall insulation and the floor insulation. Because the carpet tile, used to simulate the wall insulation was slightly thinner than the foam and also it has fibres to hold the air in whereas the foam is almost completely air tight. This may have caused the warmer air to slowly move out of the carpet when it stayed in the foam. Another theory to explain this is that, the foam I used was white and the carpet was dark green with a matt black lining on the back. I have studied before that matt black or dark surfaces radiate heat more easily than light shiny surfaces with highly polisher silvery surfaces being the best. Because of this, the carpet may have radiated the heat that it was storing away from the beaker. If I did this experiment again I could use white carpet tile or even foam as the wall insulation, this would greatly increase the accuracy of my results.
Another error that could have caused anomalous results was the fact that the beakers could have been made by different manufacturers and had different compositions. This could have made the glass conduct thermal energy more easily or radiate heat more easily then others. This would cause results that were not consistent. Next time I do this experiment I will ensure that all of the beakers are from the same manufacturer or I could even use the same beaker, though this would be time consuming.
Also loose fitting insulation that is where the insulation doesn’t completely touch the beaker all the way around. For example if the lost insulation foam wasn’t touching the beaker all the way round water could evaporate and the accuracy of the experiment would be compromised. Also if the carpet tile was a loose fit around the beaker, thermal energy could be conducted out of the glass, wouldn’t get trapped in the air in the carpet and would go straight into the atmosphere and cause inaccurate results. If I did this again I would make sure that all of the insulation was a snug fit.
There could have been errors in the double glazing because in real, modern double glazing in homes the air is sealed, air tight low pressure gas. Because it wasn’t sealed around the top air could escape with thermal energy causing erroneous results. Also the fact that there was no low pressure gas present would have affected the accuracy of the experiment. This would be very difficult to simulate in the lab without using actual double glazing. Though I could make it more air tight by putting a Vaseline seal around the top of the beakers but under high temperatures this could melt.
Physics Coursework – William Eardley 11.1