Insulation facts & stats

Question 1

Heat naturally flows in which direction?

Accepted Answer

From hotter to colder. Heat always moves spontaneously from warmer objects or regions to cooler ones.

Question 2

Which of these materials would make the poorest insulator?

Accepted Answer

Copper. Copper is an excellent conductor of heat, so it lets heat pass through easily.

Question 3

For insulation, what does a higher R-value mean?

Accepted Answer

Greater resistance to heat flow. R-value measures thermal resistance; the higher it is, the better the material insulates.

Question 4

Why is still, trapped air a good insulator?

Accepted Answer

Air is a poor conductor of heat. Air conducts heat poorly, so materials that trap small pockets of still air insulate well.

Question 5

Shiny foil barriers in walls and roofs mainly reduce which type of heat transfer?

Accepted Answer

Radiation. Shiny metal surfaces reflect infrared radiation and emit little of it, cutting radiant heat transfer.

Question 6

Which gas is commonly used to fill the gap in double-glazed windows?

Accepted Answer

Argon. Argon conducts heat less than air, so it improves the insulation of sealed double glazing.

Question 7

Which Scottish scientist invented the vacuum flask in 1892?

Accepted Answer

James Dewar. James Dewar's double-walled flask uses a vacuum to stop heat moving by conduction and convection.

Question 8

What is the SI unit of thermal conductivity?

Accepted Answer

Watts per metre-kelvin. Thermal conductivity is measured in W/(m·K): heat flow per metre of thickness per degree of difference.

The basics