I can't explain to you the number of times I have met with homeowners only to hear that that they had replaced all their home windows with energy efficient house windows and they just couldn't understand why they weren't saving any money. Typically the truth is, every window manufacturer wants you to definitely believe putting more cost effective home windows in your house is going to save you tons of money. Well it's not! You may argue with me all you want, but if you act like you have ever heard Charlie Wing speak about single pane windows you would know that you aren't getting all the information you need to make an educated decision on upgrading the home windows in your house. So let's speak a little bit about why upgrading the windows fenster in your house is one of the last things on my set of energy improvement recommendations.
First things first, they are expensive. Rarely does a windows replacement spend on itself before the end of the useful life of the window, which is often 20-25 years! In the event you have not read my previous blog post about R-value I suggest you do that now before you continue with this article.
Windows are just one part of a system that we call the "envelope" of your home. The envelope involves walls, windows, doors, roofing, and some type of flooring when it comes to dirt, concrete, rock, or other basis material. In line with the US Section of Energy, 14% of energy is going through the envelop of structures.
As with any architect, I know the value of a well-placed window that provides scale, dimension, light, and style to a building. All human beings crave light, and want to be able to see out from their homes. But replacing the double pane windows you have at home isn't going in order to save you the most money, even if they were installed more then 20 year ago. The toughest thing about energy advancements is that the products that makes the biggest difference is always the stuff you can't see.
There are two types of heat loss. Air carried heat loss (how blustering your house is) and surface transported heat reduction (how well insulated your house is). Windows actually fall into both categories. Homeowners often tell myself they want to replace their windows because they are drafty or old. Well it may well not be the window itself that is drafty, but the way it is installed. The biggest difference most householders see with a windowpane replacement is in the installation. Contractors are now caulking around the house windows, reducing airflow, and developing a much tighter building cover. We no longer products fiberglass around the shims in windows because we know it just filter systems the air coming in, it doesn't stop it. Old single pane home windows with counter weights are just large open stations for exterior air to enter the home. Thus if you have house windows with counter weights it can in your best interest to replace them. If the window has failed and has condensation inside, it's best to replace it. But if you have double hung home windows, in decent shape, upgrading to newer windows should be the last object on your set of home improvements.
The standard twice pane window has an R-value of 2. Some of the best, quickly available, windows on the market have an R-value of 5. This is excluding windows specifically made for passive house applications, which will surely have higher R-values, but also have much higher price tags. Home windows are generally listed in U-value. U-value is the inverse of R-value and for the purpose of the example below we are going to use Maine. Maine is situated in Area 6, in the current 2009 Energy Code, adopted most places. The current requirement for new building windows is U-0. 35 or R- 2. 9, hardly higher then the R-2 windows you currently have in your house, because they just don't make a glass you can see out of that has high insulating properties... yet.