Primitive windows were just holes in a wall. Later, windows were covered with animal hide, cloth, or wood. Over time, windows were built that both protected the inhabitants from the elements and transmitted light: mullioned glass windows, which joined multiple small pieces of glass with leading, paper windows, flattened pieces of translucent animal horn, and plates of thinly sliced marble. The Romans were the first touse glass for windows. In England, glass windows were seen in ordinary homes in England by the early 17th century. Modern floor-to-ceiling windows became possible only after the industrial glass making process was perfected. Various window styles developed in different regionsbased on weather variations and industrial development.
Today the customers are spoilt for choice as different types of windows are available in the market. Double-hung sash window is the traditional style of window in the United Kingdom, and regions formerly colonized by the UK, with two parts (sashes) that overlap slightly and slideup and down inside the frame. These windows were traditionally often fitted with shutters and simplex hinges, allowing the window to be opened for escape or for cleaning. Single-hung sash windows and horizontal sliding sash windows are also used in England.
Casement windows that now predominates in the UK and parts of Europe has ahinged sash that swings in or out like a door. Likewise, a tilt and turn window can either tilt inwards at the top or can open inwards hinged at the side. Widespread in many European countries, this is by far the most common window in Germany, wherefrom it originated.
Transom window is fixed either abovean exterior door or an interior door and rotates on hinges, providing ventilation before forced air heating and cooling. Used extensively in tropical architecture, a jalousie or louvered window consists of parallel slats of glass or acrylic that open and closes like a Venetian blind, usually using a crank or a lever. A common feature of Western landscape, clerestory window is set in a roof structure or high in a wall, used for day lighting. Similarly, a cupola or roof lantern is a multi-paned glass structure, resembling a small building, built on a roof for day or moon light.
Very interestingly, a French window which is as big as a door with glass panes, are very common in Italy, usually overlooking a terrace, known as portafinestra (door- window). Buildings in the Gothic Revival style often have oriel windows, which have multiple panels and originated as a form of porch in Tudor-style houses and monasteries.
Thermal windows are large semicircular windows (or niches), usually divided into three window compartments by two vertical mullions. Due to the historic unavailability of large panes of glass, multi-lit window, glazed with small panes of glass fixed decoratively, was the prevailing style of window until the beginning of the 20th century, andis traditionally still used today. Stained glass windows are especially common in churches, a window composed of pieces of colored glass, frequently portraying persons or scenes. As for emergency or egress windows in bedrooms in the United States, exact specifications are given in many building codes.
In older windows, large panes of glasswere expensive, so muntins helped smaller panes to fill a larger space. In modern windows, light-coloured muntins still provide a useful function by reflecting some of the light going through the window, making the window itself a source of diffused light. Low-emissivity coated panes also help to reduce heat transfer by radiation, depending on which surfaceis coated, helps prevent heat loss in cold climates or heat gains in warm climates.
High thermal resistance can be obtained by filling the insulated glazing units with gases such as argon or krypton, which reduces conductive heat transfer due to their low thermal conductivity. Performance of such units is dependent on good window seals and careful frame construction to prevent entry of air and loss of efficiency.
Window frames and sashes are traditionally made of wood, aluminum and steel which are often replaced by fiberglass, vinyl or PVC because of their good performancein accelerated weathering tests. Some vinyl frames are reinforced with metal or composite materials to improve their structural strength.
WINDOW FRAME MATERIALS AND THEIR IMPACTS
Aluminium: Aluminium is producedfrom its abundantly available ore,bauxite. Primary, aluminium production requires a great deal of energy ( 225MJ/ kg) and it generates huge amounts of environmentally dangerous pollutants like carbon dioxide, acidic sulphur dioxide, along with polyaromatic hydrocarbons (PAHs) fluorine and dust. Aluminium windows are light and durable made of hollow extruded profiles assembled with mechanical fasteners. Because aluminium is highly heat conductive, a thermal break, usually made of plastic, is incorporated into the frame to reduce direct conductivity between the inside and outside parts of the window. This increases the temperature of the inside surface of the framing and somewhat reduces its potential for surface condensation.
PVC: Polyvinyl chloride (PVC) is a synthetic materials, made up of repeating units of vinyl chloride. PVC is comprises chlorine, carbon, and hydrogen and its resin is 51 per cent chlorine by weight. The remainder is hydrogen and carbon, which are derived from fossil fuels: primarily natural gas and petroleum. The production of PVC is also an energy-intensive process( 70MJ/kg) and produces many poisonous pollutants such as hydrocarbons, dioxins, vinyl chloride, phthalates and heavy metals required for processing. PVC decomposes very slowly and as a waste product it contains environmentally dangerous substances that can seep out into soil and ground water.
A PVC frame is made of hollow profiles joined with heat, or solvent welded.
PVC windows are also made with metal reinforcements to increase the rigidity;this tends to increase its overall thermal conductivity. PVC windows are stable in saline and polluted air, while they have high coefficient of thermal expansion (two to three times higher than aluminium). PVC is very sensitive towards high temperature and ultraviolet (UV) radiation, which can break its molecular bonds, resulting in embrittlement and discoloration.
Timber: Timber mainly consists of cellulose, lignin and other organic substances such as proteins, sugar, resin and water. Timber can be defined asa renewable material with a very low embodied energy (5.2 MJ/kg) as compared to Aluminium and PVC. Timber is the traditional window frame material, because of its availability and ease of processing. Timber has the lowest thermal conductivity amongst frame materials. A variety of wood species are used for window frames like pine, cedar and redwood. Wood can be affected by moisture, which can make it warp or twist. Timber windows have to be painted or stained and must be maintained every few years.
Fiberglass remains the most avant-garde material for front entrance, as they have the look of wood and the strength of steel doors, without compromising on the quality. Fiberglass doors are popular as they offer the optimum combination of security, energy efficiency, performance and aesthetics.
Textured fiberglass entry doors are now available in mahogany grain and rustic collections with alder-textured plank panels, vertical fir-grain panels and oak collections. Some emulate craftsman architecture with its straightforward lines and decorative glass.
Beautifully crafted, energy efficient, secure, and easy to maintain, fiberglass hinged patio doors are a durable alternative to wood or steel. The door's exterior cladding is available in eight colours: white, tan, sand, brownstone, hunter green, cranberry, matte black and silver pearl. Wood frames with customised fiberglass doors arealso available in the market. In addition, wrought iron grilles are also mounted on the exterior of fiberglass doors to create a Western or South western look.
The grilles are available on full and three-fourths light fiberglass doors with textured and Low-E glass.
Wood Doors: Exterior French doors, as well as flat-and raised panel doors are available in extensive varieties of wood: Douglas fir, Western hemlock, red oak, knotty alder, maple, cherry, mahogany, and additional species.
Replacing flush wood doors, with moulded panel doors is an easy and inexpensive way for homeowners to add character, colour and style all over home. For remodellers, the additional selling points are that moulded doors resist swelling, shrinking and splitting caused by seasonal weather changes. Slide doors are designed to match the aluminium-clad wood windows and doors. The exterior cladding includes recycled aluminium and has an environment-friendly finish. A range of sustainable wood species can be chosen for the interior. These doors feature multipoint locking hardware and may be selected in finishes such as satin nickel and oil rubbed. Also available in the market are wood exterior door frames for maximum protection against wood decay and pest menace. These frames can be tailor-made to synchronize with the desired look for the entry system.
Steel doors: Steel doors have a wood edge and high definition style options. With decorative glass options a beautiful and durable entry door that won't crack, warp or yellow are available in the market. Opaque doors without glass come with a 20-minute fire rating. All doors are available in ready-to-paint decorative designs that come with a tough 24 or 25-gauge smooth steel surface and a polyurethane foam core for durable energy efficiency. Traditions steel doors feature a solid wood lock block for secure mounting of hardware, decorative glass options.
Vinyl and PVC: Sliding Vinyl Patio Doors come with reinforced windows for extra security and tough weather resistance to withstand strong storms and heavy rainfall.
The Green Factor: There is a great demand for doors with a 'green specification' with specific interest in sustainability and low formaldehyde emissions. Some of the established names in the manufacturing of doors are: Therma-Tru's Doors, Peachtree Doors and Windows, Milgard Fiberglass WoodClad, CMI and JELD-WEN among others.
Since double entry doors fail when theirsurface bolts break at the header trim or threshold, check the connections at both places. Be sure the surface bolt extends into the door header and through the threshold into the subfloor. Install head and foot bolts on the inactive door of double-entry doors.
Make sure your doors have at least three hinges and a dead bolt security lock which has a minimum one inch bolt throw length. (Institute for Business & Home Safety)
HEIGHT AND WIDTH
Large doors are a big trend as they combine aesthetics with functionality. Builders and remodellers are working on projects that contain higher ceilings. Wider doors, lever handles and motorized blinds are some of the door options which are in demand.
Exterior doors, both entry doors and patio doors, will continue to be bigger than the standard entry or patio doors a decade ago. As the centrepiece of an overall design scheme, entry doors are more commonly done beyond the traditional 6-ft. 8-in. heights, enlarged by sidelites and monumental transoms that flood two-story foyers with natural light. Patio door widths continue to expand, for fresh air a free-flowing impression. Pocket doors or bi-fold doors span large widths and gives a sense of design enhancements. However, individual architecture styles differ according to geographical locations. There continues to be interest in impact-resistant products along the Gulf and Atlantic Coasts, as there always has been.
Homeowners are willing to spend money on a new construction or renovation,but they want value for money. The value of a product now lies in expense versus performance. Preserving the structure, saving on energy bills and protecting the environment are thethree priorities of homeowners now. Manufacturers are responding to the demands of the customers with doorsthat meet homeowner's expectations,both aesthetically and economically. Experts offer a vital piece of advice: The importance of proper installation can'tbe overstated. No matter the product or manufacturer, proper installation is key to the performance of any door system.
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