Insulation slows energy transfer from hotter objects to cooler surroundings. It does not create energy or stop every transfer.
The higher a material’s thermal conductivity, the faster it transfers energy by conduction, when other conditions are the same.
| Change | Why it helps |
|---|---|
| Thicker walls or insulation | Energy has a longer path through the material. |
| Low thermal conductivity | Energy transfers more slowly by conduction. |
| Loft and cavity-wall insulation | Often traps air, which is a poor conductor; small pockets also restrict air movement. |
| Double glazing | A trapped layer of gas reduces transfer through the window. |
| Draught-proofing | Reduces warm air escaping and cold air entering. |
Compare wall thickness and material while keeping the temperature difference and surface area the same.
Lubricants, such as oil, reduce friction between moving surfaces. Less energy is transferred to unwanted thermal stores.
Friction is not always unwanted: brakes and tyres need it. Choose the change that suits the intended job.
Use identical cups, equal amounts of water, the same initial temperature and the same surroundings. Change only the insulation.
Measure temperature at equal time intervals. Repeat to check the pattern.
| Example cup | Start | After 10 min |
|---|---|---|
| A: bare | 80 °C | 50 °C |
| B: insulated | 80 °C | 65 °C |
B cools by only 15 °C, compared with A’s 30 °C. These are illustrative results.
Low thermal conductivity and greater thickness reduce conduction. Lubrication reduces unwanted transfers caused by friction.
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