Deck 30: Glass, Glazing, and Light-Transmitting Plastics

Question 1

Which type of gas is used in an IGU?

A)Krypton
B)Argon
C)Air
D)All of the above
E)None of the above

Answer 1

D

Question 2

If glass is 1/8 in. (3 mm)thick, it is also called

A)double- strength glass.
B)single- layer glass.
C)monolithic glass.
D)single- strength glass.
E)basic glass.

Answer 2

A

Question 3

When solar radiation falls on a glass, a certain amount of solar energy enters the enclosure through the glass. A commonly used measure of solar heat gain through the glass is called

A)CRF.
B)SHGC.
C)UVT.
D)VT.
E)none of the above.

Answer 3

B

Question 4

To obtain an IGU with a high R- value, the space between the glass sheets should be

A)hydrogen filled.
B)argon filled.
C)air filled.
D)none of the above.

Question 5

Tinted glass absorbs more solar radiation than clear glass.

Question 6

Which of the following glass types has locked- in stresses?

A)Heat- soaked tempered glass
B)Tempered glass
C)Heat- strengthened glass
D)All of the above
E)None of the above

Question 7

Which of the following indices measures the effectiveness of the transparency of glass in relation to the solar heat gain through glass?

A)LSG
B)UVT
C)SC
D)SHGC
E)None of the above

Question 8

The glass obtained from the float- glass process without any further treatment is called

A)tempered glass.
B)sheet glass.
C)annealed glass.
D)plate glass.
E)heat- strengthened glass.

Question 9

Which of the following types of glass is generally used as safety glass?

A)Annealed glass
B)Heat- strengthened glass
C)Plate glass
D)Sheet glass
E)Tempered glass

Question 10

If the reflective coating on tinted glass is on the interior surface of the glass, the solar radiation absorbed by the glass is greater than if the same coating is on the outside surface.

Question 11

A reflective coating increases the R- value of glass only marginally.

Question 12

The microscopic (atomic)structure of glass resembles that of

A)gases.
B)liquids.
C)solids.
D)none of the above.

Question 13

Surface 3 in an IGU is

A)the surface of the exterior glass sheet facing the exterior.
B)the surface of the interior glass sheet facing the intervening space.
C)the surface of the interior glass sheet facing the interior.
D)the surface of the exterior glass sheet facing the intervening space.

Question 14

Spontaneous breakage generally occurs in

A)heat- strengthened glass.
B)annealed glass.
C)laminated glass.
D)heat- soaked tempered glass.
E)tempered glass.

Question 15

To obtain heat- soaked tempered glass, the glass must be tempered first and then

A)subjected to cyclic heating and cooling.
B)annealed.
C)heat strengthened in a furnace.
D)etched.
E)all of the above.

Question 16

Which glass type is commonly specified for the spandrel areas of an all- glass curtain wall?

A)Heat- strengthened glass
B)Sheet glass
C)Tempered glass
D)Annealed glass
E)Plate glass

Question 17

To make glass transparent, the molten glass ingredients must be

A)cooled rapidly during manufacture.
B)cooled slowly during manufacture.
C)cooled very slowly during manufacture.
D)any one of the above.

Question 18

An IGU is

A)a sealed assembly of two glass sheets with an intervening space.
B)an assembly of two glass sheets with an intervening space.
C)a sealed assembly of two glass sheets with an intervening space and a spacer.
D)an assembly of two glass sheets.
E)none of the above.

Question 19

Before a reflective coating is applied on a glass, the glass must first be cut to size.

Question 20

Which of the following glass types, when broken, breaks into tiny square- edged granules?

A)Heat- strengthened glass
B)Tempered glass
C)Annealed glass
D)None of the above

Question 21

A heel bead is used in a glazing pocket.

Question 22

A heel bead is used to

A)decrease the solar heat gain through glass.
B)increase the wind- load resistance of glazing.
C)increase the R- value of glazing.
D)decrease water infiltration through glazing.
E)none of the above.

Question 23

The approximate R- value of a tinted glass sheet is

A)1)0.
B)2)0.
C)3)0.
D)4)0.
E)5)0.

Question 24

Laminated glass is

A)a sealed assembly of two glass sheets with an intervening space.
B)an assembly of two glass sheets fused together with a plastic interlayer.
C)an assembly of two glass sheets with an intervening space.
D)an assembly of two glass sheets welded (fused)together into one sheet.
E)none of the above.

Question 25

The approximate R- value of a clear glass sheet is

A)1)0.
B)2)0.
C)3)0.
D)4)0.
E)5)0.

Question 26

A glazing stop is used

A)to seal the glass against water and air infiltration.
B)as a bearing support for glass.
C)to provide a cushion between the glass and the glazing pocket.
D)to provide lateral support to glass.
E)none of the above.

Question 27

Glass can be tempered as well as laminated; that is, laminated, tempered glass is available.

Question 28

Glass is virtually opaque to

A)shortwave radiation.
B)longwave radiation.
C)ultraviolet radiation.
D)all of the above.
E)none of the above.

Question 29

Which of the following statements is true about plastic glazing?

A)It is less scratch resistant than glass.
B)It is more vapor permeable than glass.
C)It is stronger than glass.
D)All of the above.
E)None of the above.

Question 30

The primary reason for the limited use of plastic glazing in buildings is that it is more expensive than glass.

Question 31

Building surfaces emit

A)ultraviolet radiation.
B)longwave radiation.
C)shortwave radiation.
D)all of the above.
E)none of the above.

Question 32

The condensation resistance factor (CRF)of glazing is directly related to

A)the material used in framing members of glazing.
B)the R- value of the glazing.
C)whether or not tempered glass has been used in the glazing.
D)whether or not reflective glass has been used in the glazing.
E)all of the above.

Question 33

The approximate R- value of an air- filled IGU is

A)1)0.
B)2)0.
C)3)0.
D)4)0.
E)none of the above.

Question 34

The approximate R- value of an air- filled IGU with a low- E- coated glass is

A)1)0.
B)2)0.
C)3)0.
D)4)0.
E)none of the above.

Question 35

Solar radiation is

A)longwave radiation.
B)shortwave radiation.

Question 36

The R- value of an aluminum- framed glazing is generally

A)lower than that of glass.
B)higher than that of glass.
C)equal to that of glass.

Question 37

A low- E glass is a poor reflector of longwave radiation.

Question 38

Which type of glass is commonly used in drive- in bank windows?

A)Tempered glass
B)Annealed glass
C)Laminated glass
D)Heat- strengthened glass

Question 39

The minimum value of the CRF generally specified is

A)55.
B)25.
C)15.
D)35.
E)45.

Question 40

If the glass is sealed with preshimmed tape and sealant, the glazing is referred to as

A)dry/wet glazed.
B)wet/wet glazed.
C)dry/dry glazed.
D)wet glazed.
E)dry glazed.

Question 41

What is annealed glass?

Question 42

Because tempered glass (TG)has a safe breakage pattern, it is used in selected panes in multistory buildings to allow safe interior access to fire fighters, called knockout glass. However, it can be a safety hazard due to TG's spontaneous breakage, leading to glass pieces falling down from on walking areas on the ground. How do building codes address it in downtown areas where the buildings are not offset from walking areas?

Question 43

In which situations is heat- strengthened (HSG)used?

Question 44

Why is spandrel glass subjected to greater thermal stress than vision glass in a curtain wall?

Question 45

Where is tempered glass (TG)mainly used?

Question 46

What makes tempered glass (TG)stronger than annealed glass (AG)?

Question 47

Which glass type is heat- modified glass (also called heat- treated glass)and what is the purpose of heat treating glass?

Question 48

Three types of heat- modified glass are available. List them in order of the strongest to the weakest type. If any two types are of the same strength, mention so.

Question 49

What is the difference between flat glass and float glass?

Question 50

Is heat- strengthened glass (HSG)safety glass like the tempered glass (TG)? Does spontaneous breakage occur in HSG?

Question 51

The primary reason for heat- modifying glass is to increase its bending strength. How much stronger is heat- strengthened glass (HSG)and tempered glass (TG)as compared with annealed glass?

Question 52

Why is the modern glass manufacturing process called float glass process?

Question 53

What is heat- soaked tempered glass (TG)and where is it used?

Question 54

In the float glass manufacturing process, the molten glass (raw materials)floating over molten tin bath is rapidly cooled, which solidifies it into a sheet. The sheet emerging from tin bath is slowly heated in the annealing chamber and then allowed to cool to room temperature before being cut to required sizes. Why is the glass subjected first to rapid cooling and why is it subsequently heated?

Question 55

What is modern glass manufacturing process called and where was it first used?

Question 56

Why is flat glass called soda- lime glass?

Question 57

Although tempered glass (TG)is used as safety glass, it can itself be a safety hazard in some situations. Explain how.

Question 58

What is heat- strengthened glass (HSG)?

Question 59

Which raw materials are used in the manufacturing of flat glass?

Question 60

The main raw material for manufacturing flat glass is sand (silicon dioxide, also called silica). However, two other materials-sodium oxide, and lime (calcium oxide)-are added to silica. What are their roles?

Question 61

According to the glass industry, a low- E coating in an insulating glass unit (IGU)is best placed on surface 2 in warm climates and surface 3 in cold climates. However, this recommendation is modified if the IGU also has a reflective coating. What is that recommendation?

Question 62

What is the thickness of a commonly used insulating unit (IGU)in commercial buildings?

Question 63

What is light- to- solar gain (LSG)index and its importance?

Question 64

What is the difference between reflective glass and low- E glass?

Question 65

Glass industry uses a standard method of designating the surfaces of flat glass products, as 1, 2, 3, and so on. Does the numbering of surface designation begin from the outside surface or inside surface of a glass product?

Question 66

What is the difference between the U- value of glass and U- value of glazing?

Question 67

An insulating glass unit (IGU)consists of two flat glass products separated by a space containing air or a gas. What is the role of air or gas in an IGU?

Question 68

How many surfaces are there in each of the following?
(i)A single sheet of glass
(ii)An insulating glass unit (IGU)
(iii)A laminated glass
(iv)An IGU with a single sheet of glass on one face and a laminated glass on other face

Question 69

Apart from tempered glass, which other glass is considered safety glass?

Question 70

Apart from air, which other gases are used in an insulating glass unit (IGU)and why?

Question 71

Give the approximate U- value of:
(i)an IGU with low- emissivity glass and dry air space
(ii)an IGU with clear sheets of glass and argon- filled space
(iii)an IGU with clear sheets of glass, low- E coating and argon- filled space

Question 72

Name three strategies that glass manufacturers may use to produce glass with low SHGC.

Question 73

The solar heat gain coefficient (SHGC)is a ratio of two quantities. Is it > 1.0 or < 1.0? Give reason for your answer.

Question 74

What is the definition of solar heat gain coefficient (SHGC)?

Question 75

Give the approximate U- value of:
(i)single clear sheet of glass
(ii)single tinted sheet of glass
(iii)an IGU with clear sheets of glass and dry air space

Question 76

Would you specify a glass with high SHGC or low SHGC for: (i)warm climates, (ii)for cold climates?

Question 77

When direct solar beam falls on a sheet of glass, a part of solar energy is transmitted through glass into the building interior, a part is reflected, and a part is absorbed by the glass. For a clear glass sheet, the percentage of transmitted energy is 85%, reflected energy is 10% and the remaining 5% is absorbed by glass. What is your estimate of the percentage solar heat gain (SHG)of this glass, defined as the percentage of solar energy that enters the building interior? Explain.

Question 78

What is the difference between shortwave radiation and longwave radiation?

Question 79

Why must an insulating glass unit (IGU)be fully sealed?

Question 80

The low- E coating is best placed where it is protected from abrasion, i.e., on surface 2 or 3 in an insulating glass unit (IGU). What is the glass industry recommendation for the surface on which to put the low- E coating in: (i)a cold climate and (ii)a warm climate and why?