Guidelines for Use of Glass in Buildings

Guidelines for Use of Glass in Buildings
اسم المؤلف
Dr. N. K. Garg
التاريخ
2 يونيو 2021
المشاهدات
التقييم
(لا توجد تقييمات)
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Guidelines for Use of Glass in Buildings
Edited by
Dr. N. K. Garg
Professor, Faculty of Architecture
Former Head
Housing and Planning Division
Central Building Research Institute
Contents
1. Introduction 1
2. Types of Glass, Properties and Uses 7
2.1 Normal (Annealed) Glass 8
2.2 Laminated Glass 11
2.3 Tempered or Toughened Glass 13
2.4. Heat Strengthened Glass 15
2.5. Heat Soaked Tempered Glass 16
2.6 Reflective Glass 17
2.7 Insulating Glass Unit (Double Glazing) 19
2.8 Mirror 21
3. Selecion of Specific Glass 25
3.1 General 26
3.2 Heat Gain 26
3.3 Sound Insulation 36
3.4 Safety & Security 40
3.5 Strength 49
3.6 Aesthetics 49
3.7 General Information 50
4. Determination of Appropriate Thickness of Glass 57
4.1 General 58
4.2 Standard Nominal Thickness (SNT) 59
4.3 Design Considerations 60
4.4 Determination of Minimum Glass Thickness 61
4.5 Net Design Wind Pressure (Pnet) 64
4.6 Examples to Determine the Appropriate Thickness of Glass Panel for
an Office Building in Delhi Region. 70
5. Glazing Systems 103
5.1 Curtain Walling 104
5.2 Structural Glazing 1045.3 Bolted Glazing 105
5.4 Fin Supported Glazing 106
5.5 Cable Stayed Glazing 106
5.6 Suspended Glazing 107
5.7 Mirror Installation 108
5.8 Accessories for Glazing Systems 109
6. General Guidelines 117
6.1 General 118
6.2 Normal (Annealed) Glass 118
6.3 Laminated Glass 119
6.4 Tempered Glass 119
6.5 Reflective Glass 119
6.6 Insulating Glass 121
6.7 Mirror 121
6.8 Aluminium Framings 123
6.9 Safety from Earthquakes 124
Reference Material 125
Definitions
Definitions132 Use of Glass in Buildings
DEFINITIONS
Ambient Noise – The all-encompassing noise associated with a given environment, usually a composite
of sounds from sources near and far.
Ambient Temperature – The environment temperature surrounding the object.
Annealing – The process which prevents glass from shattering after it has been formed. The outer
surfaces of the glass shrink faster than the glass between the surfaces, causing strain which can lead
to shattering. Reheating the glass and allowing it to cool slowly can avoid this.
Aspect Ratio – The ratio of the longer side of a panel to its shorter side.
Balustrade – A low wall forming a parapet to a stair, ramp, balcony, raised level, or a change in
levels.
Blocks – Rectangular, cured sections of neoprene or other approved materials, used to position a
glass product in a glazing channel.
Bronze Glass – A glare – or heatreducing glass intended for applications where glare control and
reduction of solar heat are desired or where color can contribute to design.
Chair Rail – A fixed glazing bar or rigid push bar, which provides protection from human impact.
Clear Glass – As its name states, transparent or clear glass.
Clips -Wire spring devices to hold glass in a rabbet sash, without stops or face glazing.
Coating – A material, usually liquid, used to form a covering film over a surface. Its function is to
decorate and/or protect the surface from destructive agents or environments (abrasion, chemical
action, solvents, corrosion, and weathering).
Decibel (dB) – A unit adopted for convenience in representing vastly different sound pressures. It
is 20 times the logarithm to the base 10 of the ratio of the sound to the pressure of 0,0002 dyne/cm².
This reference pressure is considered the lowest value that the ear can detect.
Deflection – The degree of inward or outward movement in lites of glass exposed to unequal
pressures from either side of the glass. This condition may be permanent or temporary. Deflection
can be caused by the wind or temperature, elevation, or barometric pressure changes. Air-absorbing
desiccants can contribute to deflection.
Delaminate – To split a laminated material parallel to the plane of its layers. Sometimes used to
describe cohesive failure of an adherent in bond strength testing.
Desiccants – Porous crystalline substances used to absorb moisture and solvent vapors from the air
space of insulating glass units. More properly called absorbents.
Door – A hinged, sliding, or otherwise supported openable barrier providing entrance to and exit from
a building, corridor, or room. Doors may be framed or unframed.Definitions 133
Double Glazing – Glazing that incorporates two panels, separated with an air space for the purpose
of sound insulation or thermal insulation, or both.
Emissivity – The relative ability of a surface to radiate heat.
Fin – A piece of glass positioned to provide lateral support.
Flame Retardant – Substances mixed with rubber to retard its burning (e.g. highly chlorinated
hydrocarbons). Neoprene is less flammable than natural rubber.
Flat Glass – Pertains to all glasses produced in a flat form.
Float Glass – Transparent glass with flat, parallel surfaces formed on the surface of a pool of
molten tin.
Frequency – The number of times an action occurs in a given time period. In sound, the number of
complete vibration cycles per sound, represented by the hertz (Hz).
Frame – A structure manufactured from timber, metal, glass, or other durable material or combinations
of materials, such as glass fins and structural sealant supporting the full length of all the edges of the
glazed panel.
Gasket – Pre formed shape, such as a strip, government etc., of rubber and rubber-like composition
used to fill and seal a joint or opening, alone or in conjunction with the supplemental application of a
sealant.
Glass – A hard brittle amorphous substance produced by fusion and usually consisting of mutually
dissolved silica or silicates that also contain soda and lime. It may be transparent, translucent, or
opaque.
Glazing – The securing of glass in prepared opening in windows, door panels, screens, partitions, etc.
Heat-Absorbing Glass – Glass (usually tinted) formulated to absorb an appreciable portion of solar
energy.
Heat-Strengthened Glass – Glass, which has been subjected to special heat treatment so that the
residual surface Compression stress and the edge compression stress lies between those of ordinary
annealed glass and toughened glass.
Intensity – The rate of sound energy passing through a unit area. The intensity is measured by the
energy in ergs transmitted per second through 1 cm³ of surface. The energy in ergs per cm³ in a
sound wave is given by E = 2À² dn²a².
Interlayer – The transparent damping material used in laminated glass.
K-Value – The European equivalent of the American (ASHRAE) U-Value. The Units are
W/m2K and are based on a wind speed of 4.4 m/sec at O°C with an indoor temperature of 20°C.
Light Transmittance – Clear glass, depending on its thickness, allows 75 to 92 percent of visible
light to pass through.134 Use of Glass in Buildings
Neoprene – A synthetic rubber with physical properties closely resembling those of natural rubber
but not requiring sulfur for vulcanization. It is made by polymerizing chloroprene, and the latter is
produced from acetylene and hydrogen chloride.
Non-Residential Buildings – Buildings such as hotels, hostels, motels, shops, offices, schools,
public assembly buildings, and factories, and those parts of residential buildings common to a group of
dwellings such as common circulation areas in blocks of two or more flats.
Patterned Glass – Rolled glass having a distinct pattern on one or both surfaces.
Rabbet – A two side L-shaped recess in sash or frame to receive lites or panels. When no stop or
molding is added, such rabbets are face-glazed. Addition of a removable stop produces a three-sided,
U-shaped channel.
Reflective Coated Glass – Glass with metallic or metallic oxide coatings applied onto or into the
glass surface to provide reduction of solar radiant energy, conductive heat energy, and visible light
transmission.
Rw – Weighted sound reduction index.
Sash -A frame into which glass products are glazed, i.e., the operating sash of a window.
Sealant – A material used to fill a joint, usually for the purpose of weatherproofing or waterproofing.
It forms a seal to prevent gas and liquid entry.
Setting Blocks – Small blocks of composition, lead, neoprene, wood, etc., placed under the bottom
edge of the lite or panel to prevent its settling onto the bottom rabbet or channel after setting, thus
distorting the sealant.
Shading Coefficient – The ratio of the rate of solar heat gain through a specific unit assembly of
glass to the solar heat gain through a single lite of 3 mm clear glass in the same situation.
Skylight – A glass and frame assembly installed into the roof of a building.
Sloped Glazing – Any installation of glass that is at a slope of 15° or more from the vertical.
Solar Energy Absorption – The percentage of the solar spectrum energy (ultraviolet, visible, and
near-infrared) from 300 to 300 nm that is absorbed by a glass product.
Solar Energy Transmittance (Direct) – The percentage of energy in the solar spectrum,
ultra-violet, visible, and near infrared energy, 300 to 4,000 nanometers, that is directly transmitted
through the glass.
Sound Absorption – The property possessed by material and objects, including air, of converting
sound energy to heat energy.
Spacers – Spacers are used to prevent displacement of the glazing sealants by wind pressure on the
glass.
Span – The dimension between supports. For panels supported on all four edges, it corresponds to
the smaller of the sight size dimensions.Definitions 135
Spandrel – That portion of the exterior wall of a multistory commercial building that covers the area
below the sill of the vision glass installation.
Structural Glazing – Structural glazing is a method of bonding glass and insulating glass units to an
aluminum window frame or curtain wall system utilizing a high-strength, high-performance silicone
sealant.
Suspended Glazing – Suspended glazing is a method of providing a frame less glazing façade to fix
together a matrix of toughened glass lites, hung from the building structure.
Tempered Glass – Fully tempered (FT) glass is reheated to just below the softening point (about
1300°F or 704.4°C) and then rapidly cooled.
Thickness – The dimension between the two surfaces of a panel of glass, other than its length or
width.
Tinted Glass – Body-colored glass with specific ingredients formulated to produce light reducing
and/or heat absorbing glass products.
Toughened Glass – Glass that has been subjected to special heat or chemical treatment so that the
residual surface compression stress and the edge compression stress is greater than heat-strengthened
glass.
Transmission – The passage of sound from one location to another through an intervening medium,
such as a partition or air space.
Transmittance – The fraction of radiant energy that passes through a given material.
Ultraviolet Light (UV) – A form of luminous energy occupying a position in the spectrum of sunlight
beyond the violet and having wavelengths of less than 3900 A, which is the limit of the visible
spectrum. Ultraviolet rays are very active chemically, exhibit bactericidal action, and cause many
substances to fluoresce.
UV Transmittance – The percentage of energy in the ultraviolet (UV) spectrum, from 300 to 380
nanometers, that is directly transmitted through the glass.
Visible Light Transmittance – The percentage of light in the visible spectrum, from 380 to 780
nanometers, that is transmitted through the glass.
Wind Load – Load on glass because of the speed and direction of the wind.
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