Can anyone explain what makes windows energy efficient?

Question

I have a new home (1 yr old) with "energy efficient" windows rated well by Energy Star. I am having the same problem with these windows that I had with replacement windows in my last house. The glass itself radiates a great deal of cold air. There is more cold air than I had with my regular windows with storm windows. There are no air leaks around the windows, so weatherstripping is not the answer.

How can these new windows be considered more energy efficient?

Do all the newer energy-efficient windows have this same problem? Can I use storm windows with these windows?

Answer 1

Truly "energy efficient" windows are constructed to block heat flow by all 3 of these paths:

1.)  Convection (drafts)

2.)  Conduction

3.)  Radiation

Even a standard double-pane window is only about R-2 (compared to R-11 for a standard stud wall), so they'll be cold compared to most things.

Yes, you can use storm windows with just about anything.  You can also put up the heat-shrink plastic film; I suggest making 1x2 wooden frames and covering them with a double layer, then squeezing them into the window openings with foam gasket around the edges.  You can remove these intact and use them again for years!

Answer 2

I think because they "burn" more of our money.  Lobbyists have worked for these companies for years to get the government to require standards and to give out rebates and tax incentives.  They spend millions in advertising making us think that our old windows are allowing arctic wind into our homes.  As for your situation, you may want to find out from your builder who installed the windows.  If the maker installed them, you can call them for an assessment of your windows and their installation.  Sometimes the builder will order one type of windows but the wrong ones get installed.  This will get you some action if this happened to you.  I had about 5 good reasons to replace a door and the brand is a good one and I semi trust the guys who installed it.  BUT, the wind is whistling through it and it does not seem like a good seal.  The whole door was covered with a plastic advertisement extolling the virtues of its Energy Star ratings, blah, blah, blah.  Now here I am in the middle of winter finding out the problems and dealing with it.

Answer 3

Energy efficient windows are labeled as such for more than thier ability to keep cold air out.  It is also to keep solar energy in the form of heat from entering the house (when you are trying to cool it).  No window will be perfectly warm in the winter.  Double or triple pane windows are better than single pane.  The instalation of storm windows will add another pane in a sense and help keep more cold air out.  Think of it like this.  You wear a sweat shirt.  No shirt under it, nothing over it.  Your wear a sweat shirt with a shirt under it and nothing over it.  Which is warmer?  The one with the undershirt.  Why?  It has nothing to do with the added warmth of the extra material.  Air is exchanged between the inside of the material (next to your body) and the outside of the material.  So, one shirt will trap in warm layer of air that will slow the temperature exchange but two shirts will trap in two layers of air that will slow the temperature exchange.  Same principle with window panes.  Certain gases will in these air layers will slow the exchange even more.  This will keep not only cold air out in the winter but warm air out in the summer.  There are three types of heat.  Convention (like an oven), convection (when you blow a fan past a heater to move heat), and radiation.  Radiation is in the form of light (heat) waves.  Energy efficient windows are designed to stop radiation energy so if the sun is shining you won't get the added heat from the sun (bad in winter, good in summer).

Answer 4

"energy efficient" windows works better than other types of windows in daylight. But at night time they are the same. These glasses has special coating and gas inside the window. It was designed to allow more light go inside your house in winter but not in the summer. "So,these new windows be considered more energy efficient"

Your problem of "The glass itself radiates a great deal of cold air. " is true to all windows. That's why heaters or air ducts are installed right under the windows. May be your house has poor air circulation.

Answer 5

Glass is a great transmitter of energy. That is why triple pain windows are better than single or double pain. Add an inert gas and they are even better. Still you need to cover them at night or in the hottest part of the day.