ENERGY STAR Windows

Scope

Choose high-performance ENERGY STAR-rated windows.
Choose high-performance ENERGY STAR-rated windows.

Select and install high-performance windows, preferably windows that are ENERGY STAR rated or that meet or exceed the ENERGY STAR program requirements for windows, doors, and skylights.

If you are seeking certification under the ENERGY STAR Certified Homes program or the U.S. Department of Energy's Zero Energy Ready Home program, see the following and the Compliance tab for more specific guidance.

See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Certified Homes, and Indoor airPLUS.

Description

ENERGY STAR estimates that installing ENERGY STAR-rated windows rather than standard windows can save homeowners about 7% to 15% on their utility bills. ENERGY STAR windows typically consist of two or more panes of glass in a fiberglass, vinyl, wood, or combination frame (Figure 1). An odorless, colorless, nontoxic inert gas such as argon or krypton fills the space between the panes to provide better insulation than just air. Special low-emissivity (low-e) coatings on one or more of the glass surfaces reduce the infrared radiation from a warm pane of glass to a cooler pane, thereby making the window more energy efficient (lowering the U-factor). These coatings also reflect ultraviolet (UV) rays to minimize fading of furniture and drapes. A spacer keeps the panes of glass the right distance apart; some spacers are made of non-metal insulating materials that also insulate the edges of the glass panes reducing heat transfer through the window.

ENERGY STAR-rated windows

Figure 1 - High-performance windows like ENERGY STAR-rated windows have features like dual or triple panes, insulated frames, and low-e coatings to improve their efficiency. Reference

ENERGY STAR windows are independently performance tested according to procedures established by the National Fenestration Rating Council (NFRC). The NFRC label shows performance ratings in five categories.

  • U-Factor measures the rate of heat transfer and tells you how well the window insulates. U-factor values generally range from 0.25 to 1.25 and are measured in Btu/h•ft²•°F. The lower the U-factor, the better the window insulates.
  • Solar Heat Gain Coefficient (SHGC) measures the fraction of solar energy transmitted and tells you how well the product blocks heat caused by sunlight. SHGC is measured on a scale of 0 to 1; values typically range from 0.25 to 0.80. The lower the SHGC, the less solar heat the window transmits.
  • Visible Transmittance (VT) measures the amount of light the window lets through. VT is measured on a scale of 0 to 1; values generally range from 0.20 to 0.80. The higher the VT, the more light you see.
  • Air Leakage (AL) measures the rate at which air passes through joints in the window. AL is measured in cubic feet of air passing through one square foot of window area per minute. The lower the AL value, the less air leaks through the window. Most industry standards and building codes require an AL of 0.3 cfm/ft².
  • Condensation Resistance measures how well the window resists water build-up. Condensation Resistance is scored on a scale from 0 to 100. The higher the condensation resistance factor, the less build-up the window allows.

The NFRC label is combined with the ENERGY STAR label, which shows the U.S. regions where the labeled window meets ENERGY STAR specifications (Figure 2).

All ENERGY STAR-Qualified Windows Display the ENERGY STAR Label

Figure 2 - All ENERGY STAR-qualified windows display the ENERGY STAR label, showing the climate zones for which this product qualifies and the National Fenestration Rating Council (NFRC) ratings.  Reference

ENERGY STAR establishes U-Factor and SHGC criteria for ENERGY STAR windows based on climate using a climate zone map developed by ENERGY STAR (see Figure 3). The criteria show the highest U-factor permissible in each climate zone and the SHGC criteria in each climate zone, with higher SHGCs in colder climates and lower SHGCs in hotter climates. The climate zones shown on this map equate to the climate zones shown in the International Energy Conservation Code (IECC) map, as follows: the Southern region = CZ 1 and 2, the South-Central region = CZ 3, the North-Central region = CZ 4, and the Northern region = CZ 5, 6, 7, and 8.

Figure 4 shows the ENERGY STAR Program Requirements for Residential Windows, Door, and Skylights, Version 6.0. This version took effect on January 1, 2015, with the exception of the criteria for windows in the northern climate, which took effect on January 1, 2016.

ENERGY STAR Climate Zone Map for Windows

Figure 3 - ENERGY STAR Climate Zone Map for Windows  Reference

Figure 4 - ENERGY STAR Climate-Specific Criteria for Windows and Skylights, Version 6.0.  Reference

How to Purchase and Install ENERGY STAR Windows

  1. Determine your ENERGY STAR climate zone for the ENERGY STAR window criteria using the ENERGY STAR climate zone finder tool, which bases the climate zone on the county in which the home is located.
  2. Look for ENERGY STAR-labeled products that meet the criteria for your climate zone. If ordering from a showroom or building materials supplier, ask for a product that meets the ENERGY STAR criteria in your climate zone.
  3. If you are seeking to have your home certified under either the DOE Zero Energy Ready Home program or the ENERGY STAR Certified Homes program, see the Compliance tab for additional window specifications to meet those program criteria.
  4. Check with local utilities and check the ENERGY STAR website for information about the federal tax credit for ENERGY STAR-rated windows. Also see the DOE Database of State Incentives for Renewables & Efficiency for information on additional state, federal, and local tax credits and exemptions.
  5. Follow the manufacturer’s installation instructions when installing the windows to avoid voiding the warranty. Some warranties require that you use an installer certified by the manufacturer.
  6. Properly install windows to keep air and moisture out. See the guide  Fully Flashed Window and Door Openings.
  7. Properly air seal around window rough openings. See the guide Window and Door Rough Openings.

Table 1. Fenestration Requirements (adapted from the 2009 IECC, Table 402.1.1)

IECC table

Ensuring Success

Look for or request ENERGY STAR-qualifying products when purchasing windows, and follow ENERGY STAR criteria to purchase windows appropriate for the climate zone where they will be installed.

Climate

If you are building to meet an energy-efficiency program certification, refer to that program’s guidance for climate-specific criteria. Criteria for the DOE Zero Energy Ready Home and ENERGY STAR Certified Homes are provided in the Compliance tab.

To maximize beneficial solar heat gain and minimize unwanted solar heat gain, consider window location and sizing when designing the house. Limit the number of west-facing windows, especially in hot climates, to limit late afternoon glare and solar heat gain. Locate south-facing windows under properly sized overhangs or covered porches to minimize heat gain from high summer sun and maximize gain from low winter sun. Locating deciduous shade trees to the south and west will also minimize summer solar gain and maximize winter solar gain. Consider selecting different window models for different sides of the house to maximize beneficial solar gain and minimize unwanted heat gain (EPA 2013).

IECC Climate Zones

IECC Climate Zone Map

Training

Right and Wrong Images

Presentations

None Available

Videos

  1. ENERGY STAR Windows (1)
    Publication Date: July, 2015
    Courtesy Of: BMI

    Video describing ENERGY STAR windows.  

  2. ENERGY STAR Windows (2)
    Publication Date: July, 2015

    Video describing ENERGY STAR windows.

CAD Images

None Available

Compliance

DOE Zero Energy Ready Home Program

The U.S. Department of Energy Zero Energy Ready Home Program’s National Program Requirements (Rev 05) specifies as a mandatory requirement (Exhibit 1, #2.1) that all windows installed meet or exceed the latest ENERGY STAR Program Requirements for Residential Windows, Doors, and Skylights in effect at the time of project permitting.

The DOE Zero Energy Ready Home program allows builders to choose either a prescriptive path or a performance path in order to certify their home as a Zero Energy Ready Home. In addition to choosing windows that are ENERGY STAR labeled, builders using the prescriptive path must meet or exceed the more stringent window criteria listed in Exhibit 2 of the DOE ZERH National Program Requirements (shown in Table 1 below). Builders using the performance path must use these criteria when modeling the target home.

Table 1. Window Criteria excerpted from DOE Zero Energy Ready Home National Program Requirements (Rev 05) Exhibit 2

Windows 25,26,27
  Hot Climates
(2012 IECC Zones 1,2,)
Mixed Climates
(2012 IECC Zones 3,4 except Marine)
Cold Climates
(2012 IECC Zones 4 Marine 5,6,7,8)
SHGC 0.25 0.25 any
U-Value 0.4 0.3 0.27
Homes qualifying through the Prescriptive Path with a total window-to-floor area greater than 15% shall have adjusted U-values or SHGCs.28

Relevant Footnotes from the DOE Zero Energy Ready Home National Program Requirements:

(12) Windows shall meet the applicable ENERGY STAR Window Product Criteria based on the following schedule:

  • For projects permitted on or before 8/31/2015, windows shall meet ENERGY STAR Windows Eligibility Criteria Version 5.0.
  • For projects permitted after 8/31/2015, windows shall meet ENERGY STAR Windows Eligibility Criteria Version 6.0; except for Climate Zones 5 through 8 and Zone 4 Marine, which must follow ENERGY STAR Windows Eligibility Criteria Version 6.0 for projects permitted after 8/31/2016.

See www.energystar.gov/windows for current ENERGY STAR Windows Eligibility Criteria. For homes achieving PHIUS+ certification where triple glazed window assemblies with thermal breaks/spacers between the panes are used, such windows are deemed to meet this requirement even in the absence of an ENERGY STAR certification.

(13) Fenestration shall meet the applicable ENERGY STAR Windows Eligibility Criteria for U and SHGC, with the following exceptions:

a. An area-weighted average of fenestration products shall be permitted to satisfy the U-factor requirements;

b. An area-weighted average of fenestration products ≥ 50% glazed shall be permitted to satisfy the SHGC requirements;

c. 15 square feet of glazed fenestration per dwelling unit shall be exempt from the U-factor and SHGC requirements, and shall be excluded from area-weighted averages calculated using a) and b), above;

d. One side-hinged opaque door assembly up to 24 square feet in area shall be exempt from the U-factor requirements and shall be excluded from area-weighted averages calculated using a) and b), above;

e. Fenestration utilized as part of a passive solar design shall be exempt from the U-factor and SHGC requirements, and shall be excluded from area-weighted averages calculated using a) and b), above. Exempt windows shall be facing within 45 degrees of true South and directly coupled to thermal storage mass that has a heat capacity > 20 btu / ft3x◦F and provided in a ratio of at least 3 sq. ft. per sq. ft. of South facing fenestration. Generally, thermal mass materials will be at least 2 in. thick.

(25) All decorative glass and skylight window areas count toward the total window area to above-grade conditioned floor area (WFA) ratio.

(26) DOE strongly encourages all DOE Zero Energy Ready Home partners to consider using R-5 windows in cold climates in anticipation of them becoming the state-of-the-art window choice in the near future. Visit the DOE web site (http://www1.eere.energy.gov/buildings/windowsvolumepurchase/) for more details and sources of these windows.

(27) For homes using Exhibit 2 for Prescriptive compliance with the DOE Zero Energy Ready Home, the following exceptions to the U-Value and SHGC requirements in Exhibit 2 apply:

a. An area-weighted average of fenestration products shall be permitted to satisfy the U-factor requirements;

b. An area-weighted average of fenestration products ≥ 50% glazed shall be permitted to satisfy the SHGC requirements;

c. 15 square feet of glazed fenestration per dwelling unit shall be exempt from the U-factor and SHGC requirements, and shall be excluded from area-weighted averages calculated using a) and b), above;

d. One side-hinged opaque door assembly up to 24 square feet in area shall be exempt from the U-factor requirements and shall be excluded from area-weighted averages calculated using a) and b), above;

e. Fenestration utilized as part of a passive solar design shall be exempt from the U-factor and SHGC requirements, and shall be excluded from area-weighted averages calculated using a) and b), above. Exempt windows shall be facing within 45 degrees of true South and directly coupled to thermal storage mass that has a heat capacity > 20 btu / ft3x ◦F and provided in a ratio of at least 3 sq. ft. per sq. ft. of South facing fenestration. Generally, thermal mass materials will be at least 2 in. thick.

(28) For Prescriptive Path: All decorative glass and skylight window areas count toward the total window area to above-grade conditioned floor area (WFA) ratio. For homes using the Prescriptive Path that have a WFA ratio > 15%, the following additional requirements apply:

a. In Climate Zones 1, 2, and 3, an improved window SHGC is required and is determined by:
Improved SHGC = [0.15 / WFA] x [ENERGY STAR SHGC]
Where the ENERGY STAR SHGC is the maximum allowable SHGC in Exhibit 1, ENERGY STAR Reference Design, for the Climate Zone where the home will be built.

b. In Climate Zones 4, 5, 6, 7, and 8, an improved window U-Value is required and is determined by:
Improved U-Value = [0.15 / WFA] x [ENERGY STAR U-Value]
Where the ENERGY STAR U-Value is the maximum allowable U-Value in Exhibit 1, ENERGY STAR Reference Design, for the Climate Zone where the home will be built. 

ENERGY STAR Certified Homes 

Builders, contractors, and home owners wishing to meet the fenestration (window) requirements of ENERGY STAR Certified Homes should see the ENERGY STAR Certified Homes National Program Requirements. The latest version (Ver 3.0, Rev. 08) provides builders with a performance path that includes mandatory requirements plus a set of efficiency features builder must use to design and model a reference design house to determine the HERS Index target for the floor plan they wish to build.

The mandatory requirements specify that the builder must comply with the ENERGY STAR Rater Field Checklist, which states in item 1.1 “Fenestration meets or exceeds levels specified in Item 2.1 of the Rater Design Review Checklist.” Item 2.1 of the Rater Design Review Checklist states that fenestration “meets or exceeds 2009 IECC requirements.” The 2009 IECC window requirements are summarized in Table 1.

Table 1. Fenestration Requirements, adapted from the 2009 IECC, Table 402.1.1

IECC table

The ENERGY STAR reference design house requirements includes minimum fenestration performance requirements, which are shown in Table 2.

Table 2. ENERGY STAR Reference Design Fenestration Requirements, excerpted from the ENERGY STAR National Program Requirements Exhibit 1: ENERGY STAR Reference Design Home

 Envelope, Windows, & Doors

 Windows and doors modeled, as illustrated below:

Window U-Value: 0.60 in CZs 1,2 &0.35 in CZ 3 0.32 in CZ 4 0.30 in CZs 4 C,5,6,7,8
Window SHGC: 0.27 in CZs 1,2 0.30 in CZ 3 0.40 in CZ 4 Any in CZs 4 C,5,6,7,8

 

 

Relevant Footnotes from the ENERGY STAR Certified Homes (Version 3/3.1, Revision 08), Rater Design Review Checklist

(3)  All windows, doors and skylights shall meet or exceed the component U-factor and SHGC requirements specified in 2009 IECC Table 402.1.1. If no NFRC rating is noted on the window or in product literature (e.g., for site-built fenestration), select the U-factor and SHGC value from Tables 4 and 10, respectively, in 2013 ASHRAE Fundamentals, Chapter 15. Select the highest U-factor and SHGC value among the values listed for the known window characteristics (e.g., frame type, number of panes, glass color, and presence of low-e coating). Note that the U-factor requirement applies to all fenestration while the SHGC only applies to the glazed portion. The following exceptions apply:

a. An area-weighted average of fenestration products shall be permitted to satisfy the U-factor requirements;

b. An area-weighted average of fenestration products ≥ 50% glazed shall be permitted to satisfy the SHGC requirements;

c. 15 square feet of glazed fenestration per dwelling unit shall be exempt from the U-factor and SHGC requirements, and shall be excluded from area-weighted averages calculated using a) and b), above;

d. One side-hinged opaque door assembly up to 24 square feet in area shall be exempt from the U-factor requirements and shall be excluded from area-weighted averages calculated using a) and b), above;

e. Fenestration utilized as part of a passive solar design shall be exempt from the U-factor and SHGC requirements, and shall be excluded from area-weighted averages calculated using a) and b), above. Exempt windows shall be facing within 45 degrees of true South and directly coupled to thermal storage mass that has a heat capacity > 20 btu / ft3xoF and provided in a ratio of at least 3 sq. ft. per sq. ft. of South facing fenestration. Generally, thermal mass materials will be at least 2 in. thick.

In Passive House (PHIUS+) certified homes, where triple-glazed window assemblies with thermal breaks / spacers between the panes are used, such windows meet the intent of Item 2.1 and shall be excluded when assessing compliance of a) through e), above.

2009 IECC

Section 303.1.3 Fenestration product rating: U-factors of fenestration products (windows, doors, and skylights) are determined per NFRC 100 and labeled and certified by the manufacturer. The SHGC must be determined per NFRC 200 and labeled and certified by the manufacturer.  Products with no labels will be assigned a default U factor as listed in Table 303.1.3(1) and a default SHGC value as listed in Table 303.1.3(3).

Table 402.1.1 lists insulation and fenestration requirements by building component.

Section 402.3.1 U-factor:  an area-weighted average is allowed to satisfy the U-factor requirements. Section 402.3.2 Glazed fenestration SHGC: an area-weighted average of products with more than 50 percent glazing is allowed to satisfy the SHGC requirements. Section 402.3.3 Glazed fenestration exemption: up to 15 square feet per dwelling unit may be exempted from U-factor and SHGC requirements under the prescriptive approach.  Section 402.3.4 Opaque door exemption: one side-hinged door up to 24 square feet may be exempted from the U-factor requirement.*

2009 IRC

Table N1102.1.1 Insulation and Fenestration Requirements by Component. Section N1101.5 Fenestration product rating: U-factors of fenestration products (windows, Doors, and skylights) are determined per NFRC 100 and labeled and certified by the manufacturer. The SHGC must be determined per NFRC 200 and labeled and certified by the manufacturer.  Products with no labels must meet the requirements of Table N1101.5(1) – Table N1101.5(3). Section N1102.3.1 U-factor:  an area-weighted average is allowed to satisfy the U-factor requirements. Section N1102.3.2 Glazed fenestration SHGC: an area-weighted average of products with more than 50 percent glazing is allowed to satisfy the SHGC requirements. Section N1102.3.3 Glazed fenestration exemption: up to 15 square feet per dwelling unit may be exempted from U-factor and SHGC requirements under the prescriptive approach.  Section N1102.3.4 Opaque door exemption: one side-hinged door up to 24 square feet may be exempted from the U-factor requirement.*

2012 IECC

Section R303.1.3 Fenestration product rating: U-factors of fenestration products (windows, doors and skylights) are determined per NFRC 100 and labeled and certified by the manufacturer. The SHGC and visible transmittance must be determined per NFRC 200 and labeled and certified by the manufacturer.  Products with no labels must meet the requirements of Table R303.1.3(1) – Table R303.1.3(3). Section R402.3.1 U-factor:  an area-weighted average is allowed to satisfy the U-factor requirements. Section R402.3.2 Glazed fenestration SHGC: an area-weighted average of products with more than 50 percent glazing is allowed to satisfy the SHGC requirements. Section R402.3.3 Glazed fenestration exemption: up to 15 square feet per dwelling unit may be exempted from U-factor and SHGC requirements under the prescriptive approach.  Section R402.3.4 Opaque door exemption: one side-hinged door up to 24 square feet may be exempted from the U-factor requirement.*

2012 IRC

Section N1101.12.3 Fenestration product rating: U-factors of fenestration products (windows, Doors, and skylights) are determined per NFRC 100 and labeled and certified by the manufacturer. The SHGC and visible transmittance must be determined per NFRC 200 and labeled and certified by the manufacturer.  Products with no labels must meet the requirements of Table N1101.12.3(1)-N1101.12.3(3). Section N1102.3.1 U-factor:  an area-weighted average is allowed to satisfy the U-factor requirements. Section N1102.3.2 Glazed fenestration SHGC: an area-weighted average of products with more than 50 percent glazing is allowed to satisfy the SHGC requirements. Section N1102.3.3 Glazed fenestration exemption: up to 15 square feet per dwelling unit may be exempted from U-factor and SHGC requirements under the prescriptive approach.  Section N1102.3.4 Opaque door exemption: one side-hinged door up to 24 square feet may be exempted from the U-factor requirement.*

2015 IECC

Section R303.1.3 Fenestration product rating: U-factors of fenestration products (windows, doors, and skylights) are determined by an accredited independent laboratory per NFRC 100  (except for garage doors whose U factors can be determined in accordance with either NFRC 100 or ANSI/DASMA 105.) They are labeled and certified by the manufacturer. The SHGC and visible transmittance are determined by an accredited independent laboratory per NFRC 200 and labeled and certified by the manufacturer.  Products with no labeled U-factor must meet the requirements of Table R303.1.3(1) or Table R303.1.3(2). Products with no labeled SHGC must meet the requirements of Table R303.1.3(3).  Table R402.1.2 specifies Fenestration U-factors and SHGC values by climate zone.  Section R402.3.1 U-factor:  an area-weighted average is allowed to satisfy the U-factor requirements. Section R402.3.2 Glazed fenestration SHGC: an area-weighted average of products with more than 50 percent glazing is allowed to satisfy the SHGC requirements. Section R402.3.3 Glazed fenestration exemption: up to 15 square feet per dwelling unit may be exempted from U-factor and SHGC requirements under the prescriptive approach.  Section R402.3.4 Opaque door exemption: one side-hinged door up to 24 square feet may be exempted from the U-factor requirement.*

2015 IRC

Section N1101.10.3 Fenestration product rating: U-factors of fenestration products (windows, Doors, and skylights) are determined by an accredited independent laboratory per NFRC 100 and labeled and certified by the manufacturer. The SHGC and visible transmittance are determined by an accredited independent laboratory per NFRC 200 and labeled and certified by the manufacturer.  Products with no labels must meet the requirements of Table N1101.12.3(1)-N1101.12.3(3).  Section N1102.1.2 (R402.1.2) Insulation and fenestration criteria are listed in Table N1102.1.2 by climate zone.  Section N1102.3.1 U-factor:  an area-weighted average is allowed to satisfy the U-factor requirements. Section N1102.3.2 Glazed fenestration SHGC: an area-weighted average of products with more than 50 percent glazing is allowed to satisfy the SHGC requirements. Section N1102.3.3 Glazed fenestration exemption: up to 15 square feet per dwelling unit may be exempted from U-factor and SHGC requirements under the prescriptive approach.  Section N1102.3.4 Opaque door exemption: one side-hinged door up to 24 square feet may be exempted from the U-factor requirement.*

*Due to copyright restrictions, exact code text is not provided.  For specific code text, refer to the applicable code.

More Info.

Contributors to this Guide

The following Building America Teams contributed to the content in this Guide.

Case Studies

  1. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: January, 2013

    Case study about the first certified DOE Zero Energy Ready Home—the “Wilson Residence” in Winter Park, Florida.

  2. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: September, 2013

    Case study of a DOE Zero Energy Ready Home in west Connecticut that scored HERS 39 without solar PV. The 3,000 ft2 two-story home has R-33 double-walls, R-72 flat roof with closed-cell foam and blown cellulose, an ERV, and LED lighting.

  3. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: January, 2013

    Case study of a DOE Challenge Home in Winter Park FL that scored HERS 57 without PV or HERS -7 with PV. This 4,305 ft2 custom home has autoclaved aerated concrete walls, a sealed attic with R-20 spray foam, and ductless mini-split heat pumps.

  4. Author(s): BA-PIRC
    Organization(s): BA-PIRC
    Publication Date: November, 2013

    Case study describing a package of energy- efficiency measures for new manufactured homes in the Pacific Northwest, including triple-pane highly efficient windows.

References and Resources*

  1. Author(s): DOE
    Organization(s): DOE
    Publication Date: May, 2015

    Standard requirements for DOE's Zero Energy Ready Home national program certification.

  2. Author(s): EPA
    Organization(s): EPA
    Publication Date: September, 2015

    Document outlining the program requirements for ENERGY STAR Certified Homes, Version 3 (Rev. 08).

  3. Author(s): EPA
    Organization(s): EPA
    Publication Date: January, 2014

    ENERGY STAR specifications for residential window, door and skylights, Version 6, effective January 1, 2015. 

  4. Author(s): EPA
    Organization(s): EPA
    Publication Date: October, 2011

    Guide describing details that serve as a visual reference for each of the line items in the Thermal Enclosure System Rater Checklist.

  5. Author(s): EPA
    Organization(s): EPA
    Publication Date: January, 2013

    Information sheet outlining the criteria for ENERGY STAR qualified, windows, doors, and skylights.

Building Science-to-Sales Translator

High-R Window =
High-Efficiency Window

Technical Description: 

High-efficiency ENERGY STAR-rated windows perform at least 15% better than a standard window. Ultra-efficient windows perform at least 50% better. On average, high-efficiency windows save homeowners 7% to 15% on utility bills. These windows use a combination of insulating frames and other features to reduce heat loss. They consist of two or three glass panes separated by insulating spacers. The space between the glass layers is filled with a nontoxic gas like argon or krypton that insulates better than air and the glass panes are coated with a nearly invisible low-emissivity coating that reflects heat to keep warm air in during the winter and hot sun out in summer. The coatings also help to block ultraviolet rays, minimizing fading of curtains and furniture.

Alternate Terms

Enhanced Comfort Window
Quiet Window
High-Efficiency or Ultra-Efficient Window
Advanced Window Technology
Sun Protection Window
High-Efficiency Window
Sales Message
High-efficiency windows effectively block unwanted heat gain in summer while retaining your home’s heat in winter. What this means to you is less wasted energy along with enhanced comfort and noise reduction. Wouldn’t you agree high-efficiency windows should be included in every new home?
Last Updated: 03/14/2016

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