Deck 24: Thermal Insulation and Vapor Barriers

Question 1

Describe aerogel, including its properties and suitable uses.

Answer 1

Aerogel is a low-density material derived from gel in which the liquid component of the gel has been replaced with gas. The result is an extremely low-density solid with several remarkable thermal insulation properties. Since it is 99.8 percent air, it appears semi-transparent, making it ideally suitable as a thermal insulation material for windows and skylights.

Question 2

What is thermal transmittance?

Answer 2

Thermal transmittance (U) is a measure of the amount of heat that will pass through an assembly of various materials, such as an exterior wall. It is the reciprocal of the total resistance (R) of the assembly: U = 1/ÓR. A smaller U-value indicates greater resistance to the transmission of heat.

Question 3

Explain what is meant by permeability and describe how to interpret the permeability ratings of vapor retarders.

Answer 3

The permeability of vapor retarders is rated in perms, a measure of the rate of transfer of water vapor through a material. Vapor retarders have permeability ratings of 1.0 or lower. Materials with a perm rate of ( 1 perm) are considered impermeable, (>1 to 10 perms) semi-permeable, and (>10 perms) permeable.

Question 4

____ fibrous insulation materials include cane, cotton, wood, cellulose, and synthetic fibers.

A) Organic
B) Metallic
C) Mineral
D) Cellular

Question 5

____ is made from recycled newsprint and other paper stock that has been treated for fire and pest resistance.

A) Fibrous loose insulation
B) Loose-fill insulation
C) Cellulose insulation
D) Granular insulation

Question 6

How is heat transferred by convection?

Question 7

Heat transfer by ____ involves the transfer of heat by the circulation or movement of heated liquids or gases.

A) conduction
B) convection
C) radiation
D) insulation

Question 8

____ is a measure used to indicate the ability of a material to resist the flow of heat through it.

A) Thermal conductance
B) Thermal conductivity
C) Thermal resistance
D) Thermal transmittance

Question 9

Explain how fibrous loose insulation is made, and describe its properties and applications.

Question 10

____ polystyrene is a closed-cell foam that resists moisture absorption.

A) Extruded
B) Expanded
C) Rigid
D) Molded