What it shows
A roof of insulating material like thermocol slows the passage of heat into the house, so the inside stays cooler. The test compares four roof types.
The science
Heat from the sun reaches the roof by radiation and passes into the house by conduction. Thermocol has trapped air and is a poor conductor, so it slows the transfer. A shiny foil reflects most of the radiation, so it keeps the roof cooler. A tin roof absorbs and conducts heat quickly. This is why many houses in hot areas use lime-white, reflective or insulated roofs.
Materials
Cost: under Rs 50. Many items come from home or from waste; spare parts such as LEDs, motors and wire are in the store.
- Four identical shoeboxes or cardboard boxes
- Roof materials: plain cardboard, thermocol sheet, aluminium foil, tin sheet piece
- Four thermometers or one thermometer used four times
- A sunny spot
- Tape and a notebook
- A clock
Safety
For this project: Handle tin sheet with care; an adult must trim it and cover sharp edges. Do not leave thermometers where they can fall.
Never use mains electricity: power models with cells, batteries or a low-voltage adapter. Sharp and hot tools, flames and lab chemicals need an adult or your teacher beside you. Keep magnets, button cells and small parts away from young children, and wash your hands after making.
All the safety rulesStep by step
8 steps. Do them in order, and test each part before you go on to the next. Write what you notice in a notebook as you go.
Make a small hole in each box for a thermometer and seal the edges with tape.
Cover each box top with a different roof material.
Place the four boxes in the same sunny spot, side by side.
Record the temperature inside each box at the start.
Record the temperature every 15 minutes for two hours.
Draw a line graph with one line for each roof.
Find which roof gives the slowest temperature rise.
Explain the result using conduction and reflection.
What you should see
The thermocol and foil boxes stay cooler than the tin one, and the graph shows the difference clearly.
Viva questions
A teacher or a judge will ask how it works. Try to answer each question before you open it, then compare.
1Why is thermocol a good insulator?
It traps air which conducts heat poorly.
2Why is foil useful?
It reflects radiant heat.
3How is heat carried through the tin roof?
By conduction.
4Why keep all the boxes identical?
To make it a fair test.
Take it further
Paint one roof white and another black and compare them.
Change one thing, measure what happens, and add a table or chart of your readings: that is what turns a model into your own investigation.
Free ebooks for this project
Science projects
Physics Working Models Explained
Twenty classic models, how each works and how to make it
Science projects
Science Projects for Class 6 to 8
Working models matched to middle-school science topics