Upgrading your house windows will bring a new range of illumination into your home. In itself this improvement is important so much so that it has its own rating. The VT or Visible Light Transmission of new windows is rated in 10ths on a zero to one scale. A rating of 0.8 would be great as it allows a large amount of the light that strikes the outside to transfer into the room.
Light also transfers in the form of heat energy. A windows SHGC or Solar Heat Gain Coefficient rates the amount of heat that a window transfers from sun light striking it. This can be a tricky rating to shop for as your homes location has a lot to do with your choice. If you heat more than you cool your home (northern US) you would want a high number SHGC to take advantage of solar heat and keep your fuel generated heat inside. Hotter climates than are in a cooling mode most of the year would opt for a low SHGC number that Lets the sun in but keeps its heat component out.
The U factor is a measurement of the rate of heat loss through a window. An important cold weather factor. The lower the windows U rating the better its resistance to heat loss and the better its insulating characteristics.
Gas in your Glass? Yes Argon and Krypton gas can be found between the panes of better windows because of its ability to evenly distribute temperature in this trapped chamber between the panes. Windows panes filled with air or dry nitrogen have a tendency to fog up and stay that way after a few radical freeze thaw seasons.
May the E’s be with you, and on the inside of your multi paned windows. A Coating of Low Emission or Low -E metal oxide help s block the transfer of radiant heat through the glass and therefore helps increase the U factor which is a real plus in colder parts of the country.
Choosing the correct replacement windows sounds like it would take an engineering degree, but having the correct windows for your home can mean real savings. Having inefficient windows that let heat out in the winter is like tossing money out the window.
Simply purchasing a replacement window will not guarantee that you will save money on heating costs. Improper installation is the main reason that a replacement window does not perform as expected. If you are unsure of how to install and insulate your new windows, hire a professional and protect your investment.