Homeowners are being advised to get replacement windows when they remodel their home or buy an older home. They are told that new windows will save them money on their power bill, increase the value of their home and look like a million bucks. Homeowners are scratching their heads, wondering how replacement windows save them money. They hear words like U-factor, emissivity and triple glazed, and they look around for Captain Picard on the Enterprisefor a mission brief. What’s it all about? Glad you asked.
Energy Saving Replacement Windows
The scientific part of it all is the ingredients in the windows that prevent heat from escaping or entering. As the glass is being made, it is coated with a substance called low-emissivity film. This unbelievably thin coating acts like a two way mirror, reflecting heat back out in the summer and keeping it in in winter. Southern and western windows would benefit from this type window. Those living in cooler or otherwise milder climes would instruct their window supplier to give them windows that keep the heat in, while warmer lands would want windows that keep the heat out.
The National Fenestration Ratings Council, or NFRC, is basically the Kelley Blue Book of window ratings. Replacement windows with U ratings measure thermal heat loss through the windows in winter. This is an actual measurement, whereas emissivity is an action. The lower the U rating is the better the protection:
• Metal casement window 1.3
• Good quality single-pane window 1.0
• Good quality single-pane window with storm window .6
• Double-pane window with low-e glass .4
• Triple-pane window with low-e glass .25
Another scientific term homeowners should notice is the solar heat gain coefficient. This is another measurement telling the homeowner how much light coming in the window bears heat. In this case, the higher number the better. In mild to temperate climes, .40 to .55 is desirable.
How Does this Save Money?
Let’s say a home is leaking like a sieve, the air conditioning and heat is going 24/7, not cutting off, and not keeping anything warm or cool. That thrills the power company to pieces on one hand, but on the other hand they don’t want to cut your power off when you can’t pay the bill. Power companies usually give homeowners brownie points for installing high-efficiency windows. So does the government, in the form of tax breaks. How else do replacement windows save homeowners money?
Windows come with single, double and triple panes. Between double and triple panes can be either dead air, argon gas or the rarer and more expensive krypton gas. If heat has to battle many panes with trapped air or gas between them, it has a much smaller chance of getting inside. Most homes are built with double pane windows. The savvy homeowner installs triple pane windows with argon or krypton gas between the panes.
However, that’s not the rest of the story. Cool or warm air escapes outward through the windows. According to MemphisWindowSource.com, the window frame itself and the seal around it becomes worn and old after a time, allowing the air inside to escape. They said, “Heat senses coolness and blindly heads in its direction. This, too, drives up the power bill.” This is especially seen with the warm air in attics. Without a high R rating, the insulation isn’t enough to keep the heat from creeping into the coolness of the house. It’s the same with windows. Homeowners should check the seals and frames of their windows when contemplating replacement windows.
How this Affects Home Value
No one will buy a money pit. Homeowners selling their houses are first advised to tighten up the house with new windows and doors. Showing potential buyers the savings on power bills further convinces them to buy your house. Moreover, shiny new windows increases curb appeal, giving potential buyers a good first impression.
