How can we use air as an insulator? Give examples.

Explanation

### Step-by-Step Solution

1. **Understanding Thermal Conductivity of Air**:
- Air has a low thermal conductivity value of approximately 0.025 watts per meter Kelvin. This means that air does not easily conduct heat, making it a good insulator.

2. **Using Air in Building Design**:
- In building construction, walls can be designed with an air gap between two layers. For example, if you have an outer wall and an inner wall with a gap of air in between, this air gap will reduce the heat transfer between the inside and outside of the building.
- This design helps maintain a stable temperature inside the room, regardless of the external temperature.
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