Energy Efficiency
Find energy efficient windows to lower bills and go green. Our guides help you select the most energy smart options.

Energy Efficient Windows for Your Home

Whether building a new home or upgrading the windows in your existing home, selecting energy efficient window designs is key to comfort and energy savings. Advanced glazing, gas fills and low conduction frames minimize heat transfer. Paired with proper installation and weatherization, energy efficient windows reduce heating and cooling costs in any home.

Design Features for Energy Efficiency

Several innovations in window technology contribute to better energy performance. Prioritize these efficiency features when choosing new construction or replacement windows:

Glazing refers to the panes of glass in the window. Double glazed windows use two panes separated by an air gap, while triple glazed windows have three panes. This provides greatly improved insulation over single pane designs.

In colder climates, triple glazing is recommended for maximum efficiency. The gap between panes is typically filled with argon or krypton gas to reduce conduction.

Low-emissivity or Low-E coatings are special metallic layers applied directly on the glass surface. They reduce the emissivity, or ability of the glass to radiate heat outward.

This reflective coating improves insulation. Different Low-E formulations allow you to customize solar heat control:

  • Low-E for heating climates - reduces winter heat loss
  • Low-E for cooling climates - reduces summer solar heat gain
  • Dual-pane Low-E - balanced heat flow control

Filling the space between glass panes with argon or krypton gas instead of just air enhances insulation. These inert gasses conduct less heat than regular air.

Krypton provides somewhat better performance, though argon is more affordable. CO2 and xenon are also options but do not insulate as well.

Window frames made of vinyl, composite materials or fiberglass with internal foam insulation cuts down on conductive heat transfer, especially for colder climates.

Metal frames with thermal breaks also improve upon traditional aluminum frames. Insulated spacers further block energy transfer at the pane edges.

Newer technologies like electrochromic windows can dynamically tint to filter sunlight and reduce solar heat gain. This smart glass technology automatically adjusts to optimize daylighting and control glare.

Other advanced glazings include aerogel filled panes or vacuum insulated panels for maximum efficiency. These newer options come at a higher cost.

Energy Efficient Windows How-To Guides

Looking to make your existing windows more efficient or install new energy efficient replacement windows? Our step-by-step how-to videos and guides can help:

Review these guides for tips to maximize window energy savings and properly maintain your windows.

ENERGY STAR Certification

For reliable energy performance, look for windows certified under the EPA's ENERGY STAR program. ENERGY STAR sets standards for U-factors, Solar Heat Gain Coefficients (SHGC) and air leakage based on climate zones.

When selecting ENERGY STAR windows:

  1. Check your US climate zone map. Zones are ranked from cold to hot.
  2. Verify the ENERGY STAR label, with your zone number listed.
  3. Confirm the NFRC ratings meet or exceed ENERGY STAR requirements.

This ensures the windows meet efficiency criteria optimized for your region’s climate.

Estimated Cost and Energy Savings

Homeowners can expect the following average energy and cost savings from installing energy efficient windows:

Window Efficiency UpgradeAverage Annual Energy SavingsAnnual Heating & Cooling Cost Savings
Single pane to ENERGY STAR double pane10-15%Electric heat: $125-$340 Gas heat: $30-$135
Double pane to ENERGY STAR triple pane5-10% extraElectric heat: $60-$170 extra Gas heat: $15-$65 extra

Savings vary based on climate zone, utility rates, home layout and the efficiency of the original windows. But typically, ENERGY STAR rated windows reduce overall heating and cooling bills by 10-20% per year.

Over the 10-15 year lifespan of most replacement windows, the energy savings can add up to thousands. This helps offset the higher initial cost of efficiency upgrades.

Available Rebates and Incentives

Many utility companies and local governments offer rebates, tax credits and other incentives for installing energy efficient windows:

  • Rebates: Directly reduce upfront costs. Offered at $2 to $7 per window square foot.
  • Tax Credits: Federal tax credit of 10% of install costs, up to $500. Some state tax credits also available.
  • Financing: 0% interest and low-rate financing deals from most window retailers. Stretch payments out over time.
  • Electricity Discounts: Lower rates rewarded for efficiency upgrades in some areas.

Take advantage of these when budgeting for new or replacement windows. They can cover 10-30% of total project costs.

Installation Matters

Proper installation is crucial to ensure energy efficient windows deliver their expected performance. Here are tips for new construction or replacing windows:

  • Ensure the mounting frame is level, square and plumb. Check for flaws in framing or siding that could compromise the seal.
  • Use durable sealants like thermoplastic polyurethane or quad polymer formula at all connections and seams.
  • Provide continuous air barrier between window frame and water-resistive barrier around opening. Avoid any gaps in air sealing.
  • Install durable, minimum Class 15 exterior wall sealant around exterior perimeter.
  • Test window operation and check for uniform seal compression after installing. Operate sashes/ventilation.
  • Seal interior gaps and install insulation in any remaining voids around the window opening.
  • Consult the manufacturer’s specific installation instructions. Consider having certified professionals do the work.

Further Enhance Efficiency

For optimal efficiency and comfort, pair new windows with these added weatherization measures:

  • Insulation: Ensure walls and attics meet code minimums. R-13 for walls, R-30 to R-60 for attics. Stop drafts coming through framing gaps.
  • Caulking: Seal all penetrations on exterior walls. Use quality caulk rated for 30+ year durability.
  • Weatherstripping: Install compression seals or interlocking vinyl strips around window sashes and frames to block air infiltration.
  • Window Coverings: Use tight curtains and window shades to better regulate solar heat gain/loss. Close at night during heating and cooling seasons.
  • House Wrap: Wrap exterior walls with breathable synthetic barrier to further insulate.

With sound air sealing practices and proper installation, energy efficient windows combined with insulation and weatherization provide optimal energy savings and interior comfort.

Keys to Maximizing Window Energy Benefits:

  • Select windows with multiple glazings, Low-E coatings, gas fills and insulated frames
  • Verify proper ENERGY STAR certification for your US climate zone
  • Take advantage of rebates, tax credits and financing incentives
  • Ensure windows are professionally installed for continuous air barrier
  • Supplement with insulation, weatherstripping, window treatments

Investing in energy efficient window design, installation and weatherization helps minimize heating and cooling costs while creating comfortable indoor living spaces.

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