How Window Glass Effects Energy Efficiency

 

A low-emissivity (low-E) window coating is a microscopically thin, virtually invisible, metal or metallic oxide layer deposited directly on the surface of one or more of the panes of glass. Purchasing windows with a low-E coating are usually 10-15% more expensive than regular windows, but they reduce energy loss by as much as 30-50%.  These windows are a great investment for homeowners looking to increase their homes' energy efficiency.

 

For hot climates and unshaded windows, the low-E coating should be applied to the outside pane of glass.  Coating a glass surface with a low-E material reduces the infrared radiation from a warm pane of glass to a cooler pane, therefore lowering the U-factor of the window.  When there is a lower U-factor, there is a great resistance to heat flow by the window.  

 

 

Purchasing windows with a maximum U-factor of 0.30 and a maximum solar heat-gain coefficient (SHGC) of 0.30 allows you to receive a federal tax credit because those windows are considered "energy efficient" by the government.  The specification for SHGC only allows you to have windows with low solar-gain glass.  

 

These low solar heat gain windows are ideal for warm environments and have become widely marketed and accepted in the windows industry.  Most builders now prefer to order this type of glazing because it does meet the government's "green" standard and this type of glazing is promoted all over the country.    

 

 

Windows can have bronze or gray tinted glass.  Both bronze and gray tinted glass products are similar in energy performance.  The main purpose of the bronze or gray tint is to reduce solar heat gain, but the drawback is that it also reduces visible light transmission compared to clear glass.  

 

Tinted windows come in many colors; although bronze or gray is the norm.  Blue and green tinted glass is also available and these choices still reduce heat transmitted through the window, but allow more light through.  Purchasing tinted windows is prominently based on your own aesthetic choice and is a great investment option if your AC costs are high and you're looking for a long term solution.

 

 

Double glazed windows are made from two panes of glass that are separated by a layer of air or gas and then sealed.  These windows are designed to provide a better barrier against outside temperatures than single paned windows.  Double glazed windows, compared to single glazed windows, cut heat loss in half due to the insulating air space between the glass layers, usually filled with argon or krypton.  Gases like argon and krypton allow less heat to escape and less cold to enter. 

 

Originally, double glazing was created for extreme climates, but it is now used in practically every environment.  Double glazed windows are a great choice for any homeowner who is looking to conserve energy and reduce costly energy bills.  

 

Contact the experts at Dr. Energy Saver™ Delaware today for more information about energy efficient windows in Delaware. 

 

More Resources:

 

1. What Are Double Glazed Windows? 

Brief and Straightforward Guide: What Are Double Glazed Windows?

http://www.wisegeek.com/what-are-double-glazed-windows.htm

 

2. Double-glazed, Tinted Glass

This figure illustrates the performance of a typical double-glazed unit with bronze or gray tinted...http://www.efficientwindows.org/glazing_.cfm?id=4

 

3. Low-Emissivity Window Glazing or Glass

Low-emissivity (Low-E) coatings on glazing or glass control heat...http://www.energysavers.gov/your_home/windows_doors_skylights/index.cfm/mytopic=13430

 

4. High-Solar-Gain Glazing

Homeowners can now receive a federal tax credit for 30% of the cost of new energy-efficient windows. The credit was authorized by... http://www.greenbuildingadvisor.com/blogs/dept/musings/high-solar-gain-glazing