#Triple glazed windows r value windows

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. Sunlight is an electromagnetic form of energy exchange between the sun and the earth. T vis-glass indicates the percentage of the visible portion of the solar spectrum that is transmitted through a given glass product. 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.

#Triple glazed windows r value windows

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. 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.ДЄ window with a SHGC of 0.6 will admit twice as much solar heat gain as one with a SHGC of 0.3. As the SHGC increases, the solar gain potential through a given window increases. SHGC indicates how much of the sun's energy striking the window is transmitted through the window as heat. Total (or net) window U-factors can be considerably higher than the center-of-glass U-factors.

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).ДЄ 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. The units of U-value are: Btus per hour per square foot per вЏ (Btu/hr The higher the U-factor the more heat is transferred (lost) through the window in winter. 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. Glass Visible Transmittance (T vis-glass)ДЇor specific aesthetic and performance objectives the specifier may also wish to specify:.Window Solar Heat Gain Coefficient (SHGC), or shading coefficient (SC).To fully specify a window system, it is necessary to specify the following characteristics: Ultimately, the optimum choice of window and glazing systems will depend on many factors including the building use type, the local climate, utility rates, and building orientation. Visual requirements (privacy, glare, view).Once the design team and owner agree on the design problem, window and glazing options can be evaluated. Window and glazing choices should be considered holistically. In internal-load dominated commercial, industrial, and institutional buildings, properly specified fenestration systems have the potential to reduce lighting and HVAC costs 10%вЂ“40%. In residential, skin-load dominated structures (such as housing) optimum window design and glazing specification can reduce energy consumption from 10%вЂ“50% below accepted practice in most climates. In recent years, the variety of glass types, coatings, and frames available for use in window systems has increased dramatically, as has the opportunity to fine-tune and optimize window selection on a project-by-project basis.Д¬areful specification of window and glazing systems is essential to the energy efficiency and comfort of all buildings. Window systems are comprised of glass panes, structural frames, spacers, and sealants. This Resource Page covers basic concepts for specifying window and glazing systems, particularly energy-efficient windows. All of these features reduce heat transfer, thereby cutting the energy lost through windows. These high-performance windows feature double or triple glazing, specialized transparent coatings, insulating gas sandwiched between panes, and improved frames. High-performance, energy-efficient window and glazing systems are now available that can dramatically cut energy consumption and pollution sources: they have lower heat loss, less air leakage, and warmer window surfaces that improve comfort and minimize condensation. In recent years, windows have undergone a technological revolution. In 1990 alone, the energy used to offset unwanted heat losses and gains through windows in residential and commercial buildings cost the United States $20 billion (one-fourth of all the energy used for space heating and cooling). However, windows also represent a major source of unwanted heat loss, discomfort, and condensation problems.

Many studies have even shown that health, comfort, and productivity are improved due to well-ventilated indoor environments and access to natural light. Windows have long been used in buildings for daylighting and ventilation.