Windows FAQ

• Why are my windows drafty and will new windows stop the draft?

  
  

  Drafty windows and air infiltration could have several causes. Improper installation is often the culprit, but not always. If the windows were improperly installed, the defects can normally be corrected without removing or replacing the window.
  
  Proper caulking and flashing should prevent perimeter air leakage. However, if the installation twists or racks the window frame causing the sash weatherstrip not to be able to seal the sash to the frame, removal of the window to correct the problem may be necessary. You can determine whether the air is coming in at the joint between the frame and the house or the joint between the sash and the frame. Hold a lighted candle or lighter in front of each joint when the wind is blowing and slowly move it along the joint. If the flame flickers strongly or goes out, the joint is probably leaking.
  
  If the leak is between the frame and the sash and the window has been installed square, plumb, level and is not twisted or racked, the problem may be construction of the window or window design. If your windows are not efficient in your climate, and particularly if it does not have insulated glazing, the air may not be leakage, but simply cold room air flowing down the surface of the window.
  
  As the window surface becomes colder, it cools the room air next to it. This cooled room air is heavier than the warmer room air further into the room. Because the cooled room air is heavier it sinks toward the floor and is replaced by warmer room air, which is then cooled. This process can result in noticeable air flow, but it is not air leakage from the outside. Replacement of the window with an energy efficient window is the solution here.




• Will new windows eliminate condensation?

  
  

  Condensation is a direct result of interior humidity and the difference between indoor and outside air temperature. If you keep the humidity in your house low, the likelihood of experiencing condensation is also low. However, the efficiency of your window will also impact the temperature and humidity level at which condensation occurs. Energy efficient windows will help reduce condensation.
  
  Here's why: high performance windows with low U-factors result in inside glass surface temperatures much closer to the room air temperature. Windows with warm edge technologies and non-metal frames are also less likely to have condensation on the frame or at the edge of the glass.
  
  Insulated "superwindows" with three or more layers will virtually eliminate condensation on the interior surface of the glass -- even under extreme cold weather conditions. Note that in certain conditions (humid mornings after a clear night sky), some superwindows may have dew on their outside surface. These windows are such good insulators, the dew is condensing there just like it does on an insulated wall.

• What's the best way to evaluate a window's energy performance?

  
  

  The easiest way to compare energy performance of different windows and doors is to read the National Fenestration Rating Council (NFRC) label. It provides valuable efficiency information about the product including the u-value, solar heat gain and visible light transmittance values. Also, check to see if the product is ENERGY STAR® approved.




• What does Energy Star ® Mean?

  
  

  Originally, the Energy Star® Program was founded in 1992 as a labeling program headed by the Enivronmental Protection Agency (EPA). At first, the labels were put only on computers and computer monitors, but soon thereafter, the Energy Star® Program teamed up with the US Department of Energy and by 1996, many more product categories began to gain the label, including most, if not all appliances and home improvement goods, such as replacement windows, doors, and skylights.
  
  Now, the Energy Star® Program is affiliated with over 15,000 private and public sector organizations that help consumers find the energy efficient products they need, including replacement windows, doors and skylights.




• What is a U Factor?

  
  

  This is how much heat flows through the entire window assembly. The lower the U-factor, the better the window resists heat transfer. Windows with gaps in the assembly will have a higher U-factor than a tightly built window.




• What is SHGC?

  
  

  SHGC stand for Solar Heat Gain Coefficient. The SHGC is the ability of the window to block the sun's heat. The more heat a window blocks, the lower vinyl windows ratings will be for heat gain.