Introduction
Benefits
Equipment & Services
Hiring Contractors

1. Introduction

Making the decision to replace your windows involves many factors including energy efficiency, comfort and home resale value. Windows are part of the home envelope and inefficient windows contribute to air leaks and cause comfort problems.

If energy efficiency is the main reason you’re considering a window replacement, be sure to consider the other measures your home needs as well. Insulating your home and sealing up air leaks while you have your windows replaced can dramatically increase the energy savings you will enjoy from your overall project. If you are replacing windows, this information will help you choose the right window and evaluate companies.

2. Benefits

Energy Savings
Inefficient windows can add 10-25% to heating bills and up to a whopping 75% to summer air conditioning bills. As with every energy upgrade, actual savings are dependent on many factors unique to your home. 

Comfortable Living
Windows are a primary source of home comfort problems and energy-efficient windows will make a noticeable impact on your home living environment. Imagine being able to sit on the couch in front of a window and not feel cold. And, they provide increased sound control.

Increased Home Value
Energy efficient replacement windows is an investment that also pays dividends when you sell your home. Windows are the only energy measure that every home buyer is sure to look at when comparing homes. According to a 2004 Cost vs. Value Report from Remodeling Magazine and REALTOR® Magazine, the national average cost recouped at sale of the home was 84.5%.

Conservation
Taking a whole house approach to energy efficiency helps the environment. In 2004, one of our Energy Makeover Contest winning homes succeeded in reducing emissions by 58%.

3. Equipment & Services

There are numerous variances in how windows are manufactured and installed. Three are key measures of the window’s energy performance. To fully explore window options, visit the Efficient Window Collaborative online, EfficientWindows.org.

The U-Factor measures the amount of heat (in BTUs) that moves through the window. The lower the U-value, the better the overall insulating value. Look for windows with a U-Factor of 0.35 or lower, the ENERGY STAR® standard.

• Solar Heat Gain Co-efficient (SHGC) measures the amount of solar energy passing through the windows. Efficient windows usually have a SHGC between 0.3 and 0.4, unless they are designed for colder climates and south-facing windows to take advantage of passive solar heat gain.
• Air Infiltration or Air Leakage measures the rate at which air passes through cracks in the window. It is measured in cubic feet of air passing through one square foot of window area per minute. The lower the value, the less air leakage. The best windows have an air leakage rating between 0.01 and 0.06 cfm/ft.
• Do you have too many windows?  Some newer homes have greater window areas and reducing the amount of window area will usually cut energy costs. Increasing south-facing window area will let the sun provide more heat in the winter (shade those windows in the summer). Reducing east and west facing window area will keep a home cooler in the summertime.
• Important Window Considerations. In addition to measurements, you should consider the following features of energy-saving windows.
  • Multiple layers of glazing. A double layer has twice as much insulating value as a single layer.
  • Thickness of air space. Many window manufacturers have increased the thickness of the air space in their double-glazed windows from ¼" to ½" or more.
  • Low-conductivity gas fills. For gas fills like argon and krypton, ask where the gas is filled. If the gas-filled window experiences a high altitude variance in shipping, it is possible for the invisible gas to escape.
  • Low-e coatings. Thin, transparent coatings of silver or tin oxide permit visible light to pass through, but effectively reflect infrared heat radiation back into the room reducing heat loss
  • Edge spacers. The edge spacer holds the panes of glass apart and provides the airtight seal in an insulated glass window. Aluminum has been widely used for decades, but it has extremely high conductivity. Now, other materials that have less conductivity are being used and/or thermal breaks are incorporated into the window design.
  • Frames. Consider frames that are wood, vinyl or fiberglass.
  • Architectural options can affect the energy performance of windows.

4. Hiring Contractors
Download our window company comparison form (Acrobat reader .pdf format). Find a window company from our list of contractors.

Questions to ask
Because windows require a notable investment, it is important to choose a quality company that will be able to stand behind their warranty long-term.

Certifications

• National Fenestration Rating Council (NFRC.org) is a non-profit organization that administers an independent rating and labeling system for the energy performance of windows.
• American Architectural Manufacturers Association (AAMA) is the source for performance standards, product certification, and educational programs. The AAMA online Certified Products Directory helps research products that achieve air, water, structural and forced entry resistance code compliance.
• AAMA also runs a well-respected installation certification program.
• Efficient Windows Collaborative (efficientwindows.org) offers a website that provides unbiased information on the benefits of energy-efficient windows, descriptions of how they work, and recommendations for their selection and use.

References, licensing, insurance
It is always important to speak with previous customers, check with the Better Business Bureau and ask for verification of the necessary licensing and insurance requirements. Download a home improvement hiring checklist from the Federal Trade Commission.

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