Choosing replacement windows for your home is not an easy task.
As you've discovered, there are many variables to balance when making the selection:
- energy efficiency,
- aesthetics, and the
- frame material's effect on the environment.
Each homeowner has their own unique criteria for making the final decision, and only after becoming knowledgeable about these variables can you make the right decision for your situation.
Replacement versus new-construction windows
Replacement windows ("inserts") are different from new-construction windows (stripping out flashing and trim down to the studs) and will usually look different, both outside and inside, from the windows currently on your home.
The advantage of using replacement windows is that they fit within the existing openings and can be quickly and easily installed without the need to patch the exterior siding material or interior drywall. When you use a replacement window, the new window itself will be more energy efficient than your old single-pane window, but there will still be air infiltration and leakage through the walls around the window and the channels and gaps in the framing around the window openings.
With new-construction windows, these areas can be insulated and sealed, creating a much more energy-efficient home, but the process takes several days and is more expensive.
Frame materials and thermal performance
The material you choose for the window frame (vinyl, fiberglass, wood, or cladding over wood) will affect the overall thermal characteristics of the window.
- The Efficient Windows Collaborative has a great website to help you understand the effect of the window frame materials on energy efficiency.
- Vinyl and wood are comparable in U-value (a measure of the rate of non-solar heat loss or gain through a material or assembly).
- The lower the U-factor, the greater a window's resistance to heat flow and the better its insulating value.
Fiberglass is a dimensionally stable material (meaning that only slight shrinkage and expansion occur with changes in temperature and humidity), and when the cavities of the window frame are insulated, the thermal performance exceeds that of wood or vinyl.
Learning how to use the National Fenestration Rating Council (NFRC) certification label will help you choose the most energy-efficient windows.
Homeowners interested in green products will want to consider more than energy efficiency when choosing the materials used in the construction of their new windows.
It is important to look at the entire life cycle of the product and its effects on the environment from the manufacturing process through its serviceable life, as well as what happens to it when it is removed from our homes.
Vinyl. There is continued debate in the green building community, and in the vinyl industry, about the environmental health hazards caused by the production and disposal of vinyl products. Although theoretically vinyl is recyclable, only about one percent of the material produced is actually recycled annually, and more than 14 billion pounds are produced each year. It takes generations for vinyl products to degrade in a landfill. There is more plastic in the ocean than plankton, and for an environmentalist, the thought of adding to that is distressing! When vinyl is incinerated, toxic dioxin is the byproduct.
Concern about whether vinyl windows offgas while installed in your home is probably greatest if you are extremely sensitive. Other vinyl products like shower curtains and flooring products with more exposed surface area are a much bigger threat to indoor air quality.
Fiberglass. Fiberglass is composed of 60 percent glass, or silica (sand), a common and plentiful resource. The other agents present in the production of this material are formaldehyde, urea, sulfuric acid, phenol, and ammonia.
- If proper precautions are not taken during the manufacture of fiberglass, the workers exposed to these materials may suffer serious health effects.
- The production of fiberglass takes significantly less energy than producing vinyl.
- Fiberglass does not offgas, so there are no air quality issues with fiberglass windows.
- Theoretically, fiberglass is recyclable, but like many products, windows are often discarded into the landfill at the end of their usable lives. It is our responsibility-homeowners, contractors, and manufacturers-to appropriately recycle products.
Wood. Woodand wood-clad windows might be the most environmentally friendly choice when looking at the life-cycle issues, especially if the wood is certified from a sustainable source.
- Look at Andersen Renewal, Marvin, and JELD-WEN windows.
- Each of these manufacturers has information online about their environmental stewardship program.
Aesthetics and affordability
If aesthetics are a priority, wood and wood-clad windows can more closely match the look of your original wood windows.
Wood. Woodwindows with a thin cladding of vinyl or aluminum on the exterior, and either painted or stained on the interior, look more traditional and are easy to maintain.
The cladding is offered in several colors to coordinate with the exterior of your home, and never needs to be painted. Wood windows are generally more expensive than vinyl or fiberglass.
Fiberglass and vinyl. Fiberglasshas a few color options and can be painted, but vinyl windows come in very few colors, show a lot of frame and less glass, and are usually vinyl inside and outside.
- They cannot be painted to blend with either interior or exterior colors.
- There are a few manufacturers making vinyl windows with a thin veneer of wood-or laminate mimicking wood-on the interior, but the least expensive vinyl windows are white or off-white plastic, inside and out.
As you can see, there are many, many factors to consider when choosing your replacement windows.
As with many green products, you have to balance the pros and cons of each option, and your individual needs and concerns, in order to make the right choice for your home.
For more information:
GreenHomeGuide pros have answered many more questions about making a more energy efficient home.
Also, read "Are there any nontoxic, non-offgassing replacement windows available? Also, how does one identify nontoxic sheetrock in stores?" a Q&A answered by David Edwards.