HouseWindows

House Window Glass

House window glass is a complex set of products with endless options for homeowners looking for new or replacement windows for their homes. Appearance and price are the top concerns for house window glass shoppers, but energy efficiency is on everyone's radar now that the green movement is sweeping the country. The glass you choose and your home window shades can have a huge impact on your utility bills.

Inefficient window glass has a lower price tag, but the amount of energy wasted in some climates can be astounding. Making the initial investment in house windows with efficiency technology can save you money over months and years, and they windows actually pay for themselves over time. Your house will maintain a more comfortable interior temperature and you can breathe a sigh of relief when the bills come each month.

Types of Glass

The type of house window glass you choose depends on your environment. People who live in extreme climates--very hot or very cold--benefit the most from energy efficient windows. City dwellers in milder climates will want to reduce street noise. In the Midwest and places with extreme weather, glass that can withstand wind and debris is a primary concern.

Low-emittance glazing controls the amount of solar heat that radiates through a window. A transparent metallic coating is sandwiched in the panes to prevent solar heat from entering the room while allowing light to penetrate. This keeps homes in warm climates cooler in summer. In cold weather, the coating reflects interior heat off of the window back into the room, rather than conducting it through to the outside.

Without this technology, energy is lost through conduction, convection and radiation. Conduction is the direct transfer of heat through a solid. Convection occurs when warm interior air gives up its heat to the cold glass and drops to the floor, creating a draft. Radiation is the movement of infrared energy through the window in the form of solar heat.

The second type of house window glass is laminated. Two pieces of glass are bonded together with a tough inner layer of plastic under heat and pressure so they behave as one piece. This type of house window glass has two distinct benefits. First, the plastic layer prevents the window from shattering into fragments. The shards adhere to the plastic so the unit can be removed safely, preventing injury.

Shatter-proofing is important for very large house windows and windows placed where they could pose a threat to people underneath. Windows that exceed 16 square feet, like picture windows or other stylized applications, should be laminated. If the highest point of the windows is 12 feet above any walkway or living space, lamination is highly recommended. Finally, if the pane is thicker than 3/16 of an inch, it should be laminated.

The second benefit is noise reduction. Laminated house window glass in a well-insulated units can significantly improve Sound Transmission ratings, a measure of the amount of noise nuisance transmitted through building materials. The plastic inner layer works with the double panes to dampen the sound and lessen its intensity. This can make the house more comfortable by muffling the sounds of densely-populated areas.

The third type of house window glass is tempered. Tempering windows gives them strength against thermal stress and impact resistance. Tempering works through a process of compression. The whole unit is heated, then the surface is cooled rapidly. This leaves the center relatively hot; as it cools, it forces the surfaces and edges to compress.

In hurricane and tornado zones, tempered windows can resist wind and foreign object impact. Windows placed too close to vents and furnaces can crack when outside temperatures cause them to contract and internal heat causes them to expand rapidly. This thermal stress leads to frequent replacement, but not with tempered panes.

Types of Windows

Various forms of house window glass are combined to form whole units. Choosing the right technologies adds another layer of complexity to selecting new and replacement windows. Climate is the most important factor in your decision, and choosing the right energy efficiency for your house can yield substantial savings.

Double-glazed and triple-glazed windows are so energy efficient that single pane windows are difficult to find in some markets today. Old, outdated single pane windows are thermal holes in the house that can cause up to 30 percent of energy to be lost. Double-glazed windows are made of two panes with a gas or air fill. Triple-glazed windows add another layer of insulation.

The air and gas fills work as buffers to extreme temperatures and noise. Air fills are less expensive and sufficient for moderate climates. Argon or krypton are more costly, but make a noticeable difference in cold climates. Incorporating the house window glass that meets your needs into your double- or triple-glazed window will give you the best possible performance.