Energy Efficiency Factors Important in Considering Replacement Windows
Heat Transfer Through Glass
In over 150 years, glass manufacturing has remained virtually the same. Windows in a 40-year-old home will transfer heat through the glass at about the same number of BTUs (British Thermal Units) as windows in a brand-new home. The solution to improving heat transfer is not in the glass but is in the upgrades to the glass. A double-pane window with no upgrades will transfer approximately 200 BTUs through the glass testing with a standard heat lamp. If you put your hand on the inside of the window glass, the glass will feel warm. The atmosphere in the room adapts to this heat transfer blocking some of the cooling that may be desirable.
Low E Coatings
Low E (low emissivity) coatings on the glass prevent some heat transfer improving the room atmosphere. It’s important to determine which type of Low E is needed. Low E2 is an energy-efficiency coating applied to the inside of the inner glass in a double-pane window. This is a basic upgrade that improves heat transfer, a good solution for windows that do not face the afternoon sun. Low E3 consists of a second coating applied to the inside of the outer glass. The two coatings work together to significantly improve heat transfer.
Argon is an inert gas which is colorless and odorless. This gas is commonly used in double-pane windows to add major improvements in heat transfer thereby lowering energy bills. Argon gas is used with Low E2 and Low E3 coatings to give the most benefit in keeping rooms cool and also warm in the winter when desired.
Low E3 Argon windows can reduce heat transfer to approximately 40 BTUs, a significant drop from standard double-pane windows with no upgrades. An extra benefit of Low E3 Argon is the ability to repel winter cold from penetrating the glass, allowing heat to remain in the room atmosphere when desired. The added benefit of reducing air conditioning costs as well as heating costs is one of the major reasons why customers upgrade to Low E3 Argon replacement windows.
Window Frames and Construction
An additional important factor to consider when replacing windows is the frame material and how it is manufactured. Vinyl windows are very long-lasting and maintenance-free. If purchased in standard colors offered by the manufacturer, vinyl windows generally have a lifetime warranty.
How the window is manufactured is crucial. The most long-lasting, securely-framed window will be a multi-fusion welded window in which a perfectly-squared frame is produced in a special welding machine that completely fuses the entire frame at one time. It is not “spot-welded” which may produce a window frame that deteriorates over time due to small structural changes in the foundation of a home.
Double-strength glass is very important to the long-lasting integrity of a window. Double-strength glass holds up extremely well to impacting objects such as storm debris and the occasional small stones kicked up by lawn mowers. Another important factor is the ability of double-strength glass to improve heat transfer along with the Low E Argon upgrades. Single-strength glass would serve very little benefit with the energy-efficient upgrades available in today’s replacement windows.
America’s Best Choice Siding and Windows, serving Springdale, Fayetteville and Bentonville Arkansas, recommends vinyl Low E3 Argon replacement windows to offer the best benefit in energy savings available today to our customers. All windows we install are multi-fusion welded frames with double-strength glass providing the longest-lasting maintenance-free products.