Home Energy-Efficient Windows

According to the U.S. Department of Energy, leaky and inefficient windows, skylights and doors account for up to 25 percent of the average household's energy bills. Some sources estimate as high as 40 percent. A lot depends on where you live:

  • Cold climates lose energy in the form of heat
  • Hot climates lose energy in the form of cooling

The colder or hotter the climate, the greater your heating or cooling costs and the greater potential you have to save money on energy costs. Nearly everyone can benefit by replacing leaky, inefficient windows with modern energy-efficient windows. Depending on your location, you can cut energy costs by as much as 15 percent.

A Smart Investment

Energy Performance Ratings

NFRC Label

Replacing all of a home's windows can be a big investment. The good news is, it's an investment that can pay for itself in just a few years. Here's how:

  • Improves curb appeal and increases resale value. According to the 2008/09 Cost vs. Value Report (a combined effort by Remodeling magazine and REALTOR® magazine), homeowners can expect to recoup about 93% percent for vinyl or wood window replacement.
  • Reduces heating and/or cooling costs, which saves you money every year.
  • Increases the comfort of your home.
  • Can qualify you for rebates and tax incentives, like the Federal Energy Tax Credit, which provides up to $1,500 for any efficiency improvements made to your home in 2009 and 2010. (Save your sales order or NFRC label from the window and check for rebates and tax incentives in your area.)

    Learn more about the Federal Energy Tax Credit
    Take advantage of the Milgard Energy Rebate

To find out more about the many benefits of energy-efficient windows, visit the Efficient Windows Collaborative. The window selection tool on this site helps determine an approximate change in annual energy use given your home type, window type and geographic region.

Components of an Energy-Efficient Window

What's an energy-efficient window? Most will have at a minimum:

  • Double-pane insulated glass
  • Heat-resistant (Low-E) glass coating
  • Airtight frames
  • ENERGY STAR® rating

Three Dimensions of Energy Efficient Window Design—An energy-efficient window is a synergy of its components. At Milgard®, we call this the "three dimensions of energy efficient window design." Here's what you should look for in each of the three dimensions: glass, spacer and frame.

Frame, glass and spacer illustration

Frame – One of the important considerations you need to make is frame material. Two of the more energy efficient frame materials are vinyl and fiberglass. They do a particularly good job of reducing heat transfer and contributing to insulation value. Your ultimate decision on which of these to use may be based on aesthetics and cost. In making your selection, be sure to look for vinyl or fiberglass frames that have been specifically engineered for performance. For instance, both can be designed with chambers within the frame that enhance strength, noise reduction and insulation value.

Glass – Dual-pane designs use an air- or gas-filled space between two panes of glass. This insulates much better than a single pane. Special Low-E coating on the glass blocks infrared light to keep heat inside in the winter and outside in the summer. It also filters damaging ultraviolet light (UV) to help protect interior furnishings from fading.

Spacer – A spacer keeps a window's dual glass panes the correct distance apart for optimal airflow between panes. Too much or too little airflow can affect the insulating glass efficiency. The design and material of the spacer also can make a big difference in the ability to handle expansion and contraction and thus reducing condensation.

Energy Star

ENERGY STAR is a joint program of the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy (DOE). Its mission is to help us all save money and protect the environment through energy-efficient products and practices. EPA and DOE set strict energy-efficiency guidelines for ENERGY STAR qualified products. In 2007 alone, ENERGY STAR helped Americans save more than $16 billion on their utility bills. For more information on ENERGY STAR qualified products, visit www.energystar.gov.

To become ENERGY STAR qualified, windows, doors and skylights must be independently tested and certified by the National Fenestration Rating Council and labeled according to ENERGY STAR climate zones. Manufacturers like Milgard® (an ENERGY STAR partner) tailor the components of their windows to work most efficiently where you live.

Take Advantage of the new 2009 Federal Tax Credits – President Obama revised the tax credit with the American Reinvestment and Recovery Act of 2009, signed into law on February 17. These revisions supersede the previous tax credit issued for 2009. Windows, doors, and skylights must now have a U-factor and Solar Heat Gain Coefficient (SHGC) less than or equal to 0.30, regardless of climate zone.

Other Tax Credits, Rebates and Offers – Many states and other governmental bodies, utilities and organizations offer rebates, tax credits and other special offers when you buy ENERGY STAR qualified products. Use the Special Offer/Rebate Finder on this page to see what's available in your area.

ENERGY STAR is a registered trademark of the U.S. government.

Energy Tax Credit

Our all-inclusive energy packages make qualifying simple. Talk to other window companies about energy efficient windows and they'll tell you about pieces and parts. Not Milgard. We make it easy to select windows that meet the energy tax credit requirements, without mixing and matching components from a confusing list of options.

Here's How the New Federal Energy Tax Credit Program Works1

Section 1121 of the stimulus package allows for a federal energy tax credit to homeowners, up to 30% of the cost of window and door replacement (or, a maximum $1,500 for taxable years 2009 and 2010). The tax credit is for the cost of the product only and does not include the cost of installation. To qualify, windows and doors must have a 0.30 U-factor and 0.30 Solar Heat Gain Coefficient (SHGC) or better. Learn more about federal tax credits for energy efficiency on the ENERGY STAR® website.

Many Milgard® Windows and Doors2 with the optional 3D/3D MAX® Energy Package upgrade or Triple Glazed option, can meet these requirements and help homeowners qualify for the Energy Conservation Incentives of the 2009 American Recovery and Reinvestment Act.

All Milgard products are custom made to order. If there is any question about a specific window qualifying for the federal energy tax credit, set up an in-home estimate or see your local Milgard Certified Dealer.

The NFRC Label

NFRC Label

Replace old windows and doors. Get up to $1,500 tax credit.

Here's how to qualify:

Learn more:

  • Learn more about federal tax credits for energy efficiency at www.energystar.gov. ENERGY STAR® is a registered trademark of the U.S. Environmental Protection Agency.
  • Learn more about the Economic Stimulus Plan (American Recovery and Reinvestment Act of 2009) at www.irs.gov.



Based on the best data available, this information is a partial summary of the revisions to the federal tax code (U.S. Code Title 26, Section 25C), as updated by the American Recovery and Reinvestment Act of 2009. Taxpayers should check with IRS regarding updates to the IRS interim guidance in Notice 2006-26. Other energy efficient improvements may apply. Check the IRS website for more details. Milgard bears no responsibility for the validation of obtaining the tax credit. Milgard Windows & Doors is not a tax advisor and recommends you consult your tax planner and review all IRS guidelines.

Milgard does not intend to provide and is not providing legal or tax advice on this web site and recommends that purchasers consult their own tax advisor to determine whether the windows and doors they purchase qualify for the tax credit.


Grids and large size windows can have a negative effect on SHGC performances. Check with your Milgard dealer for more information.

Products which are shipped to or over altitudes higher than the elevation of manufacture may require capillary tubes to relieve pressure in the insulated glass units. These products do not qualify for the 3D MAX® Energy Package.

“ENERGY STAR” is a registered trademark of the U.S. Environmental Protection Agency.

If there is any question about a specific window meeting the 0.30 U-factor and 0.30 SHGC criteria to help qualify for the federal tax credit, please see your Milgard Certified Dealer.


Last Updated (Friday, 27 November 2009 17:41)