Glazing is another important part of choosing your windows and should be considered holistically. There are many factors to consider like building orientation , utility rates , building use type , local climate and surrounding safety and noise factors .
Choices to consider include the following :
- Heat gains and losses
The 3 top most common talked about values are :
U-value indicates the rate of heat flow due to conduction, convection, and radiation through a window as a result of a temperature difference between the inside and outside. The higher the U-factor the more heat is transferred (lost) through the window in winter.
- The units of U-value are: Btus per hour per square foot per °F (Btu/hr · ft² · °F)
- U-factors usually range from a high of 1.3 (for a typical aluminum frame single glazed window) to a low of around 0.2 (for a multi-paned, high-performance window with low-emissivity coatings and insulated frames).
- A window with a U-factor of 0.6 will lose twice as much heat under the same conditions as one with a U-factor of 0.3.
Solar Heat Gain Coefficient (SHGC)
SHGC indicates how much of the sun’s energy striking the window is transmitted through the window as heat. As the SHGC increases, the solar gain potential through a given window increases.
- The SHGC is a ratio between 0 and 1. SHGC = 0 means none of the incident solar gain is transmitted through the window as heat and SHGC = 1 means all of the incident solar energy is transmitted through the window as heat.
- A window with a SHGC of 0.6 will admit twice as much solar heat gain as one with a SHGC of 0.3.
- Typically, windows with low SHGC values are desirable in buildings with high air-conditioning loads while windows with high SHGC values are desirable in buildings where passive solar heating is needed.
- The term “SHGC” is relatively new and is intended to replace the term “shading coefficient (SC).” While the terms are related, the shading coefficient of glass is defined as the ratio of the solar heat gain through a given glazing as compared to that of clear, 1/8 inch single pane glass.
Visible Transmittance (Tvis-glass)
Tvis-glass indicates the percentage of the visible portion of the solar spectrum that is transmitted through a given glass product.
- Sunlight is an electromagnetic form of energy exchange between the sun and the earth. It is composed of a range of electromagnetic wavelengths, generally categorized as ultraviolet (UV), visible, and infrared (IR) referred to collectively as the solar spectrum.
- The short, UV wavelengths are largely invisible to the naked eye, but are responsible for fabric fading and skin damage. Visible light is made up of those wavelengths detectable by the human eye. This light contains about 47% of the energy in sunlight. Longer IR wavelengths are also invisible and contain about 46% of the energy in sunlight.
- For a given glazing system, the term “Coolness index (Ke),” also called Efficacy Factor, is the ratio of the Tvis-glass to the shading coefficient (SC).
REFRENCE : WBDG – Whole Building Design Guide – National Institute of Building Sciences
PLANITHERM ONE represents the most advanced thermal insulation performance within the PLANITHERM family. It offers the lowest possible centre pane U-value available from a double or triple glazed unit in the UK today.
COOL-LITE SKN 176 II is a solar control product that features a high performance coating. The coating is applied to PLANICLEAR float glass by cathodic sputtering under vacuum conditions.
COOL-LITE SKN 176 II forms part of the ever-evolving range of ‘to be toughened’ neutral solar control coatings from SAINT-GOBAIN GLASS. In order to achieve its superior thermal properties, solar control properties and neutral appearance, COOL-LITE SKN 176 II must always be toughened or heatstrengthened before assembly into a double-glazed unit (coating on face 2).
BIOCLEAN is a low-maintenance self-cleaning glass manufactured by depositing a transparent layer of photocatalytic and hydrophilic mineral material onto clear glass. The coating, which is integrated into the glass itself, ensures a high level of durability. The mechanical, thermal and acoustic properties of BIOCLEAN are identical to normal glass.
Can your glass take the heat? If not, it’s time to try GLASSOLUTIONS’ heatied glass. Able to withstand cold environments without creating excess condensation inside, E-GLAS converts electrical power into warmth to create an automatic ‘snow melting’ function. It’s ideal for use in windows in cold and wet environments, and can heat both outward and inward.
Laminated safety and security glass, STADIP or STADIP PROTECT, comprises two or more sheets of glass bonded together with one or more interlayers of polyvinyl butyral (PVB) film.
STADIP glass incorporates a single PVB sheet with a nominal thickness of 0.38 mm, distinguishing it from STADIP PROTECT glass which has a minimum thickness of 0.76 mm. Laminated glasses with different levels of safety and security can be obtained by varying the number and/or thickness of each of the components.
If the glass breaks, the fragments of glass are held in place by the PVB interlayer(s). In fully framed installations the broken glass retains a residual strength while awaiting replacement.
SATINOVO is a unique frosted glass which is valued for its attractive appearance and smooth, satin-like appearance.
It is produced by acid-etching the surface of PLANICLEAR glass to produce the uniform matt frosted finish.
SATINOVO therefore offers a solution for multiple applications and markets where a feature design element is desired or simple vision control.
Privacy glass – often known as smart glass, intelligent glass or switchable glass – is ideal for providing opaque glass on demand in commercial buildings and residential properties.
Manufactured to the highest standard by Saint-Gobain, PRIVA-LITE technology is a thermal and sound-insulating laminated glazing solution incorporating a liquid crystal film that can manage transparency on demand, changing instantly from clear state to translucent, and vice versa.
The liquid crystals align when the electrical current is switched on, causing the glass to turn transparent instantly. When the power is switched off, the glass has a naturally opaque appearance, blocking vision (total privacy), yet permitting light to pass through (translucent).
Watch the video to find our more information about our switchable privacy glass, PRIVA-LITE.
SGG STADIP SILENCE is a laminated sound-insulated safety glass. It is composed of two or more layers of glass assembled using one or more films of sound-insulated polyvinyl butyral: sound-insulated PVB or PVB Silence.