Chapter 17

True

(true or false) The strength and toughness of chemically strengthened glass can exceed those of tempered glass.

true

(true or false) chemically strengthened glass can be cut after strengthening, but can not be used as safety glazing unless it is laminated.

true

(true or false) when drawn in small fibers glass is stronger than steel, though not nearly as stiff.

Photovoltaic

__________ glass is coated with a thin film of amorphous silicon that generates electricity from sunlight, and can thus help reduce the buildings net electricity consumption.

chromogenic

__________ glass is glass that can change its optical properties.

Fire protection rated

__________ glazing is used within fire rated door and window assemblies.

tension

microscopic imperfections that are an inherent characteristic of glass reduce its useful strength to significantly lower levels, particularly in ______

Security glass

(Laminated Glass type) ________ used for drive in banking windows and other facilities that must be resistant to burglary, is made of multiple layers of glass and PVB, and is available in a range of thicknesses to stop any desired caliber of bullet.

true

(true or false) Buildings dominated by a heating load, glass with high SHGC is preferable to take advantage of passive solar heat gains. And in buildings dominated by cooling, glass with Low SHGC is preferred to help minimize unwanted solar heating.

true

(true or false) Laminate glass can also qualify as safety glazing like tempered glass.

annealed

Ordinary window glass is ______ meaning that it is cooled slowly under controlled conditions to avoid locked in thermal stresses that might cause it to behave unpredictably in use.

U factor

The performance of glazing as a thermal insulator is quantified as its _________. Lower values represent improved thermal performance.

Low emissivity

The thermal performance of glazing can be improved substantially by the use of glass with ___________ coating. Which are ultra-thin, virtually transparent and almost colorless metallic coatings that selectively reflect solar radiation at different wavelengths. -commonly used in double glazing -reduces thermal transmittance -allows double glazing to exceed the performance of triple glazing. -Can provide high visible light transmittance with low solar heat gain.

Visible light transmittance

The transparency of glass to visible light is called its ______________________. It is measured as the ratio of visible light that passes through the glass relative to the amount of light striking the glass.

Reflective

Thin durable fils of metal or metal oxide can be deposited on the surface of either clear or tinted glass sheets under closely controlled conditions to make ___________ coated glass also called solar control glass

-not as strong as annealed glass -when it breaks the soft interlayer holds the shards of glass in place rather allowing them to fall out. -useful for skylights and overhead glazing

What are some characteristics of laminated glass?

-sand -soda ash -lime

What are the major ingredients of glass?

-single strength (3/32 to 1/8) -Double strength (up to as much as 1 inch)

What are the two categories of thicknesses for glass?

glazing

____ refers to the installation of glass in an opening or to the material itself.

lights (lites)

______ are individual pieces of glass

float glass

______ has become the worldwide standard replacing both drawn glass and plate glass. -ribbon of molten glass is floated across a bath of molten ten, where it hardens before touching a solid surface.. -results: high optical quality, brilliant surface finish -used to make nearly all glass in building today

Gasochromic

_______ glass is glass whose transparency is altered by the pumping of gas into or out of the interstitial space of the unit

Patterned

________ glass , which is hot glass rolled into sheets with many different surface patterns and textures, is used where light transmission is desired but vision must be obscured for privacy.

self cleaning

________ glass is coated with titanium oxide on its exterior surface. The coating acts as a catalyst that enables sunlight to convert organic particles to carbon dioxide and water. Coating applied only to the outside of the glass so the interior must be washed manually.

tempered glass

________ has higher residual stresses than heat strengthened glass and is about four times as strong in bending as annealed glass. -qualified for use in safety glass. -used for hockey rings, handball courts -more costly than annealed glass -cutting, edging and drilling must be done before the heat treatment of the glass.

Wired glass

________ is annealed glass with wire mesh embedded in it while hot used for glazing in fire doors and fire windows. -today most fire protection rated glazing is wire free.

Laminated glass

________ is made by sandwiching a transparent ployvinyl butyral interlayer between sheets of glass and bonding the three layers together under heat and pressure.

Glass

________ on its own is a poor thermal insulator.

Tinting

_________ glass reduces its visible light transmittance. It is made by adding small amounts of selected chemical elements to the molten glass mixture to produce the desired hue and intensity of grays, bronzes, blues, greens, and golds. However does not reduce the overall solar heat gain because the glass absorbs the heat and it is usually transferred into the building.

laminated glass

_________ is a better barrier to the transmission of sound than solid glass.

heat strengthened glass

_________ is lower cost, and may be used instead of tempered glass. The induce compressive stresses in it are about 1/3 as those in fully tempered glass -twice as strong in bending than annealed glass -more resistant to thermal stress -fewer distortions than tempered glass -cutting and other fabrications can be done after it has been heat treated. -cannot be used as safety glass

Glazier

_________ is the installer of the glass

suspended glazing

_________ systems are used primarily for high walls of glass around building lobbies and enclosed grandstands.

Double glazing

__________ cuts the rate of heat loss in half and a third sheet (triple glazing) reduces the rate of heat loss to about a third of the rate through the single sheet.

Photochromic

__________ glass becomes darker when exposed to bright light.

thermochromic

__________ glass becomes darker when it is warmed by the sun.

Electrochromic

__________ glass changes its transparency in response to the passage of electric current.

heat treated glass

__________ is produced by reheating annealed glass in an oven , then quenching both of its surfaces rapidly with blasts of air while its core cools much more slowly. Both tempered glass and heat strengthened glass as examples of this. -induces permanent compressive stresses in edges and faces. -tensile stresses on core -stronger than annealed glass and more resistant to thermal stress and impact.

Glass mullion

__________ system , the tempered glas sheets are suspended from above on special clamps and are stabilized against wind pressure by perpendicular stiffeners, also made of tempered glass. Tension cables, structural columns, and glass fittings may be used to brace the glass.

Crown glass

___________ created by blowing a large glass sphere, the heated glass sphere was adhered to an iron rod called a punty opposite the blow pipe. Sphere was then reheated and the glassworker then spins the punty rapidly causing centrifugal force to open the sphere into a large disk.

Fire rated

___________ glass may be used in buildings in two ways, glazing within fire doors and fire window, or with more recently available higher performing glass products, as a complete substitute for rated wall assemblies.

Chemically strengthened glass

___________ is produced by an ion exchange process that takes place when annealed glass is immersed in a molten salt bath. The glass is prestressed in a manner similar to the one that occurs with heat treating. -Does not experience the optical distortions or warping that are common with heat treated glass.

Solar heat gain coefficient

___________ is the effectiveness of glass in reducing heat gain from solar radiation. It is the ratio of solar heat admitted through a particular glass to the total heat energy striking the glass.

fritted

___________ or silkscreen glass, the surface of the glass is imprinted with silkscreen patterns of ceramic based paints. Can be used to control the penetration of solar light and heat into a space.

laminated glass

____________ also is used in blast resistant and wind-borne debris resistant glazing systems, and block the transmission of most ultraviolet radiation.

Fire resistance rated

____________ glazing can substitute in full for solid fire rated wall assemblies.

Safety glazing

____________ means that the material must be resistant to impact and must be constituted such that if it does fail, it does not break into knife like, potentially threatening shards.

spandrel

_______________ glass also uses frits to create special opaque glass sheets for covering spandrel areas in curtain wall construction. Usually tempered or heat strengthened to resist the thermal stresses caused by solar heating behind the spandrel.

Tinted and Reflective

________________ glass products are one method used to reduce unwanted sunlight from entering a building, to reduce visual glare and unwanted solar heating within the building.

Light to solar gain

_________________ ratio is the visible light transmittance divided by the solar heat gain coefficient. It is a useful measure for determining overall energy conserving potential of glass.

plate glass

glass cast into frames, spread into sheets by rollers, cooled , then ground flat and polished with abrasives, first one one side and then the other. -costly, but near perfect optical quality.

cannot

heat strengthened glass ___________ be used as safety glazing except in laminated form.