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WHAT YOU NEED TO KNOW ABOUT WINDOWS, DOORS AND SKYLIGHTS
Windows, doors and skylights are designed to give access to exterior air, light and spaces. But by nature, they also make it easier for air leakage and heat transfer to occur. Energy loss happens when:
- Heat or coolness is directly conducted through glass, glazing, frames and doors
- Heat from the sun radiates into an air-conditioned house—or interior, furnace-generated heat radiates to colder exteriors
- Leaks allow temperature-regulated air to move into or out of a house
As heat is drawn out in cooler weather—or light and heat seep in during warmer weather—energy is lost, and furnaces and air conditioners must work harder to maintain comfortable interior temperatures.
According to the U.S. Department of Energy, for example, windows can account for 10-25% of your heating bill. To combat this energy loss and save money, you can make some small changes to your current doors, windows or skylights by installing more energy efficient models or making smaller changes to limit energy loss.
To learn more about saving energy with optimized windows, doors and skylights, consult the FAQ below.
Windows, Doors and Skylights FAQ
- How can I reduce the energy lost from my current windows, doors and skylights?
- What should I look for in new windows, doors and skylights?
- How much do energy efficient windows, doors and skylights cost?
- What should I keep in mind if I’m hiring a contractor?
- How much money and energy will I save?
- Are there additional benefits to replacing my windows, doors and skylights?
- What rebates and incentives are available?
- Are there any laws or regulations I need to be aware of?
There are many ways you can reduce your home electricity use without buying new products:
In cold weather:
- Seal heavy-duty, clear plastic sheets to window frames to reduce infiltration
- Use insulating window shades on drafty windows
- Keep curtains and shades closed at night
- Use windows with southern exposure to let in the warmth of winter sun by keeping windows clean and blinds and curtains open during the day
- Install strong, durable, low-e storm windows with weather-stripping (this step alone can reduce heat loss through the windows by 25-50%)
- Keep current storm windows in good repair
- Install a storm door and add weather-stripping around any door’s movable joints
In warm weather:
- Use lighter-colored or white shades, drapes or blinds to reflect heat away from the house
- Keep blinds, drapes and curtains on south- and west-facing windows closed to limit heating from direct sunlight
For more information:
Visit the U.S. Department of Energy’s windows, doors and skylights page:
There are a number of technologies that make windows, doors and skylights more energy efficient. Among them are multiple panes of glass, warm-edge spacers between panes, improved framing materials and low-e coatings.
For windows in Colorado:
- Check for a low U-factor, which describes the rate at which non-solar heat flow is conducted. In general, Coloradans require a U-factor of 0.35 or less to meet ENERGY STAR guidelines.
- Choose Low-E glass, which is coated with a clear, energy-saving film
- Choose a gas-fill of argon, krypton or another inert gas, which provides some insulation
For most parts of Colorado, look for doors with a Northern Climate Zone ENERGY STAR certification, which should include:
- A U-factor of 0.35 or less
- Wood, steel, fiberglass or composite material
- Low-E glass
For most parts of Colorado, look for skylights with a Northern Climate Zone ENERGY STAR certification, which should include NFRC-certified performance ratings of:
- U-Factor: 0.60 (NFRC 2001) or less*; 0.45 (RES97) or less**
- Low-E glass
- Wood, vinyl, fiberglass or composite frame material
- Gas fill of argon, krypton or other inert gas (not used in all units)
*NFRC2001 procedures, fully adopted in April 2004, rate skylights at a 20-degree angle.
**NFRC1997 procedures rated skylights of residential and non-residential sizes at a 90-degree angle. Residential 1997 (RES97) ratings may be in use until March 31, 2008. NFRC labels for these products will state: 'RES97 rated at 90 degrees.
For more information:
Learn about and find manufacturers of ENERGY STAR rated windows, doors, and skylights.
See the U.S. Department of Energy’s windows, doors, and skylights Energy Saver’s page.
Download the U.S. Department of Energy’s Energy Savers Booklet.
Prices vary, and may or may not include installation. As a general rule, energy efficient windows cost $425-$700 each; insulating exterior doors costs $200-$3000 each, and skylight upgrades cost $200-$3000 each.
For general tips, including what to ask a potential contractor, how to compare bids and how to monitor quality, please visit the How to Hire a Contractor page.
In addition to the general tips on our How to Hire a Contractor page, you may need to consider some specific issues when hiring a contractor for this particular kind of work. Here are some additional things to keep in mind:
- To get the most out of your windows, doors and skylights, have them installed by trained professionals according to manufacturer instructions. Otherwise, your warranty may be void.
- If installation requires scraping lead-based paint, be sure to take proper precautions.
- If you plan to install ENERGY STAR windows or doors, be sure to look for the ENERGY STAR label and confirm that the product is ENERGY STAR rated for your specific climate zone.
For more information:
To search a list of contractors in your area provided by the Better Business Bureau, visit the Energy Action Planner, right on this site.
Learn how to install a door yourself.
ENERGY STAR windows can reduce your energy bill by 15%. For example, if you live in the Denver area, this translates to $395 in savings per year over single-paned windows and $50 per year over double-paned windows.
If you live in the Grand Junction area, this translates to $380 in savings per year over single-paned windows and $60 per year over double-paned windows.
In addition to energy and financial savings, energy efficient windows and doors have other benefits such as:
- Protection from winter chills—Inefficient windows pull heat away from your body, so you can feel chilly even in a sweater with the thermostat at 70 degrees. With ENERGY STAR qualified windows, the interior glass stays warmer, so you can enjoy your window seat even when the temperature outside dips well below freezing.
- Reduced condensation—Indoor moisture can condense or even freeze on the interior surface of inefficient windows. Over time, chronic condensation can damage sills, cause paint to crack and encourage the growth of mold. Advanced technologies enable ENERGY STAR qualified windows to keep the interior of the glass and frame warmer, reducing the potential for condensation and ensuring a clearer view on winter mornings.
- Shielding from summer heat—A typical double-paned, clear-glass window allows approximately 75% of the sun’s heat into your home. Most ENERGY STAR qualified windows transfer much less heat, typically without reducing visible light. You get the light you need without the uncomfortable heat.
- Safeguarding your valuable interiors—Your favorite photograph, your child’s artwork and even your couch can fade or discolor after repeated exposure to direct sunlight. Most Low-E coatings, the same coatings that keep out the summer heat, act like sunscreen, blocking damaging ultraviolet rays without noticeably reducing visible light.
There are a number of financial incentives and programs available. See the Energy Action Planner for additional information on financial incentives in your area.
Be sure to check local regulations regarding installation of windows, doors and skylights.