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Shading and Solar Control for Windows and Skylights

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    Exterior shading devices such as awnings or overhangs can significantly reduce cooling loads
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    Ensure adequate protection from solar heat gain through windows, doors, and skylights to reduce cooling energy consumption, improve a home’s resistance to extreme heat events, and improve comfort.

    • When possible, site and design homes to avoid direct sunlight through windows during the cooling season. Minimize east- and west-facing window area.
    • Select windows, skylights, or storm windows with the lowest solar heat gain coefficient (SHGC) practical for your climate. (See the High-Performance (ENERGY STAR) Windows guide, the Low-E Exterior Storm Windows guide, and the Interior Storm Windows and Panels guide.)
    • During construction, pre-wire windows for potential use of motorized and automated shading systems to enable smart and dynamic control of solar gains through windows.
    • Integrate exterior architectural shading designs, attachments, and landscaping to block direct sunlight through windows and glass doors during the cooling season.
    • Incorporate interior window attachments to supplement exterior systems and allow versatile solar control.
    • Avoid skylights. If using skylights, minimize area. Consider using north-or south-facing clerestory windows instead.
    • Select interior and exterior shading attachment systems that are rated by the Attachments Energy Rating Council (AERC) to ensure that products have a low SHGC and a high “Warm Climate” performance rating to optimize performance in the cooling season.
    Description
    Description

    Solar radiation is a major contributor to heat gain in most homes. Heat gains from solar radiation through the glazed areas of a home (windows, glass doors, and skylights) can be reduced significantly by using exterior and interior shading attachments, architectural shading elements, landscape shading, and high-performance glass.

    There are numerous benefits to implementing shading and solar control strategies for a home, including the following:

    • Increased "hours of safety" provided by the home during extreme heat events. This is particularly important if air conditioning has failed or is not available.
    • Reduced energy consumption, cost, and emissions due to reduced load on the air conditioning (A/C) system.
    • Increased comfort. Even with A/C, shading can improve localized comfort.
    • Reduced wear on the A/C system. This results in less maintenance and longer equipment life.
    • Reduced A/C equipment size. Smaller equipment results in lower first-cost and potentially a smaller footprint.
    • Reduced exposure of interior and exterior surfaces to UV radiation. This can slow the fading and deterioration of fabrics, furniture, wood flooring or decking, trim, siding, plastics, and painted surfaces.
    • Impact-resistance during high-wind events. Some shading devices are designed to perform double duty as protection against flying debris during hurricanes or tornadoes.
    • Protection from rain. Some shading devices, such as roof overhangs and window awnings, protect windows, trim, and siding from rainwater.
    • Heating energy savings. Some shading devices, such as interior cellular shades, can reduce nighttime heat losses through windows during the winter.
    • Improved outdoor living space. Some shading systems, such as porches and pergolas, create extra outdoor space that can be used throughout much of the year (Figure 1).
    • Increased home value. The curb appeal of homes can be improved through design features like covered porches or landscape features like shade trees.

     

    Figure 1. The patio roof on this home creates an attractive outdoor living space and provides full shade to large glass doors and windows while maintaining important door and window functions such as view from the inside, easy door access for ingress and egress, airflow, and daylighting. (Source: NREL 2000)

     

     

    Windows, skylights, and doors perform multiple functions such as access, natural light (daylighting), visual connection to the outdoors, architectural interest, solar heat gain in winter, and ventilation for cooling or indoor air quality. These must be balanced with the potentially large heat losses in winter and heat gains in summer that are attributable to these glazed areas. A good shading system will preserve the beneficial functions of windows, skylights, and glass doors while minimizing heat gain in the summertime.

    Characteristics of Sunlight 

    Sunlight can be divided into two primary forms: direct beam solar radiation and diffuse solar radiation. Direct beam solar radiation consists of parallel rays of sunlight and diffuse solar radiation consists of scattered rays of sunlight. Direct beam radiation is responsible for glare and intense heating of surfaces, while diffuse radiation can be utilized as a pleasant, natural source of light.

    To minimize heat gain, direct beam radiation should be blocked. Diffuse radiation, on the other hand, can be encouraged as a natural light source to reduce the use of heat-generating, energy-consuming, artificial light.

    How well a shading system blocks direct beam radiation is highly affected by the daily and seasonal changes in the position of the sun in the sky. The sun’s interaction with the home changes throughout the year. In the summer, the amount of solar radiation striking the roof and the east- and west-facing walls increases significantly as compared to the south-facing wall (See Figure 2).

    Figure 2. Sun paths through the sky in winter, spring, summer, and fall show that a home receives sunlight mostly from the south in the winter and the east-west in the summer. (Source: Courtesy of FSEC)

     

    In most latitudes, the summer sun shines directly on east and west walls and windows for significantly more hours than it falls on north and south walls. In the middle of the summer, unshaded east-west windows receive as much as two times more solar heat per square foot than unshaded south-facing windows at the latitudes of the contiguous United States. As the season moves toward late summer, south-facing windows and walls receive increasing amounts of sunlight, eventually outpacing the east and west exposures from fall to spring.

    The path of the sun in the summer months greatly increases solar radiation on the roof and skylights as well. One square foot of roof area can receive approximately three to four times as much solar radiation on a midsummer day as one square foot of north- or south-facing wall. See Table 1.

     

    Table 1. In midsummer, the roof and skylights will receive much more solar radiation per square foot than an unshaded east- or west-facing wall or window, which in turn will receive more solar radiation per square foot than north- or south-facing walls and windows, as shown in this example from Boulder, CO. (Source: NREL 1995)

     

    General Shading Strategies Based on Orientation

    When adding summertime shading, focus on skylights first, east- and west-facing windows second, south-facing windows third, and north-facing windows last. Understanding the sun’s path through the sky allows more effective shading design.

    East-and West-Facing Windows

    During the summer, the east side of the house receives low sun directly facing the wall in the morning as well as high sun at an angle to the wall toward midday. The low, morning solar angles are best shaded by vertical shading in front of the window, such as a shrub or tree, trellises, solar screens, shutters, and interior shading such as roller shades or blinds. Late morning and midday sunlight can be effectively blocked by horizontal overhangs. Deeper overhangs will begin to be effective earlier in the day than shallower overhangs. Very deep overhangs such as porch roofs or pergolas can be very effective on the east side except in the earliest parts of the day. This type of shading will reduce heat gain in the winter as well as the summer, however. Combinations of horizontal and vertical shading, such as a roof eave plus roller shades, can be an excellent and versatile approach that allows solar heat gain in the winter if desired. The same shading strategies that work on an east-facing window will also work on a west-facing window.

    South-Facing Windows

    The south side of a home receives sunlight from mostly high in the sky during the summer. Properly sized horizontal overhangs or roof eaves are very effective for south-facing windows (Figure 3). Properly designed, this type of shading can block all direct sunlight during the summer while allowing direct sunlight in during the winter when the sun is lower in the sky. See the Architectural Shading section of this guide for information on sizing overhangs.

     

    Figure 3. Infrared photometry shows the impact of a roof overhang on the south façade of a home, where the unshaded patio stonework is significantly hotter than the shaded portions of the patio and wall surfaces (temperature scale is in Celsius, peaking at 116°F). (Source: Courtesy of FSEC)

     

     

    North-Facing Windows

    The north side of a home receives low sun in the morning and evening during the summer, but at a significant glancing angle from the east or west. Vertical side-shading is effective here such as permanently attached wall fins (Figure 4) or vertical shrubbery planted to the sides of a window. Shading of north-facing windows is generally not a high priority, but in  very low latitudes it should not be neglected.

     

    Figure 4. Vertical side-shading, such as these side fins, can provide effective summertime shading for north-facing windows, but are generally not recommended for other orientations due to their marginal performance and restricted views as compared to horizontal shading devices. (Source: LBNL 2023)

     

     

    Skylights

    The roof receives sunlight all day long, at very direct angles as well as glancing angles. Tall shade trees can be effective for shading skylights, as well as interior attachments such as automatic blinds.

    Vertical Front-Shading (All Orientations)

    In virtually all orientations, some form of vertical shading is usually required to block direct-beam solar radiation during some parts of the day or year. The closer to due east or west a window faces, the more valuable this type of vertical shading becomes. Vertical shading can be as simple as interior blinds or roller shades, which can be conveniently (or automatically) opened and closed based on the time of day and whether there is direct sunlight on the window (Figure 5).

     

    Figure 5. Interior window attachments such as these light-filtering roller shades provide vertical shading in front of the window; they are an excellent supplement to exterior horizontal shading devices because they provide shade regardless of where the sun is in the sky. (Source: AERC 2023)

     

     

    Methods of Shading and Solar Control

    Methods of solar control for windows and skylights include high-performance glazing (glass), landscape shading, architectural shading, exterior attachments, and interior attachments. Figure 6 shows an array of exterior shading options.

     

    Figure 6. There are multiple options for exterior shading of glazing systems to reduce heat gain to a home (Source: Courtesy of FSEC).

     

     

    High-Performance Glazing (Glass)

    One of the most effective ways to reduce solar heat gain is simply to install high-performance low-emissivity (low-e) windows with a low solar heat gain coefficient (SHGC). Low SHGC storm windows are also a highly effective option for retrofits. SHGC is a measure of how much solar heat a window assembly will allow to pass through. Windows with lower SHGC values transmit less solar heat.

    For information on high-performance windows, see the High-Performance (ENERGY STAR) Windows guide, the Low-E Exterior Storm Windows guide, and the Interior Storm Windows and Panels guide.

    When selecting new or replacement windows, glass doors, or skylights, choose units that are ENERGY STAR rated for your region. See the ENERGY STAR Residential Windows, Doors, and Skylights webpage as well as the ENERGY STAR Storm Windows webpage. See also the Climate tab of this guide for guidance on regionally appropriate ENERGY STAR windows.

    Landscape Shading

    See the Landscaping to Reduce Cooling Load guide for in-depth information on how to use landscaping as a source of shade. Landscaping can be utilized to greatly reduce solar gains through windows and skylights. Tall trees with a high canopy can function in a similar manner to horizontal overhangs and are appropriate for south-facing windows and doors. They are also one of the only feasible options for shading a roof or skylights. Deciduous trees located on the south side of a house will block summer sun while allowing beneficial solar heat gain in winter. Large shade trees separated from the house by some distance can block lower-angle sunlight from the east or west while preserving views and breezes. Shrubbery close to the house can also provide excellent vertical shading but may restrict views. Figure 7 shows the impact of a well-placed tree at a residence in central Florida.

     

    Figure 7. Infrared photometry shows the impact of landscape shading on the surface temperatures of a home (temperature scale is in Celsius, ranging from 79°F to 102°F). (Source: Courtesy of FSEC)

     

     

    Architectural Shading

    Architectural shading includes roof eaves, overhangs, fins, latticework, vertical trellises, horizontal pergolas, porches, decks, and other elements that are designed into the structure of the home. When designed properly, architectural shading will block direct solar radiation in the summer while allowing solar heat gain in winter. Good shading will allow diffuse daylighting into the home, preserve views, allow access to breezes and ventilation, and allow access to egress and ingress if needed (Figure 8).

     

    Figure 8. The south face of this home has an overhanging second floor, a pergola, and a roof eave to provide effective window and door shading for both floors in the summer without blocking views, daylighting, breezes, or ingress and egress. (Source: Courtesy of PNNL)

     

     

    Horizontal Shading Elements

    Horizontal shading such as overhangs, roof eaves, and pergolas are very versatile in application and can preserve views and other beneficial aspects of windows and doors, as shown in Figure 8 above and Figure 9 below. These systems are particularly applicable for south-facing windows and doors due to their ability to block high summertime sun angles.

    Figure 9. Porch roofs, pergolas, and large overhangs can effectively shade windows and doors facing south, southeast, southwest, or even due east or west for most of the day if the overhang is very deep and sufficiently wide. (Source: Courtesy of UCLA Energy Design Tools Group, copyright 2008, 2014 Regents of the University of California; modified by PNNL)

     

    Solar panels mounted as overhangs for south-facing windows can provide shade while producing electricity (Figure 10). Roof eaves are also a great dual-purpose application (protection from sun and rain), but can typically only provide shade for the top story of a home. On a two-story home, roof eaves will do little to shade first-floor windows.

     

    Figure 10. The photovoltaic solar panels installed on the south face of this home perform double duty as window overhangs for summertime shading. (Source: City of Burnsville 2023)

     

    Sizing Horizontal Overhangs

    When correctly sized for the home’s latitude, a south-facing horizontal overhang will provide full shade in summer while allowing direct solar gain in winter (Figure 11).

     

    Figure 11. This overhang for a south-facing window provides full shade in the summer and full sun in the winter, optimizing savings in both cooling and heating energy (results shown for 2pm in both summer and winter, 36N latitude). (Courtesy of PNNL)

     

    Guidance and online calculators for sizing overhangs can be found from a number of sources on passive solar design. The guidance can vary significantly from source to source, so it is worthwhile to understand the logic behind any recommendation. A few key concepts will aid a designer in selecting a method for sizing overhangs:

    • Most readily available guidance on overhang or eave sizing is intended only for windows facing due south. Best practice recommendations should change based on window orientation.
    • Some sources of guidance only consider peak solar angles at the summer solstice and the winter solstice when recommending the depth of an overhang. Best practice guidance considers heat gain throughout each hour of the day and each month of the year, with the goal of optimizing the balance between shading in the cooling season and heat gain during the heating season.
    • The height between the top of the window and the bottom of the overhang must be taken into consideration. This dimension has a strong effect on whether the overhang can provide full shade throughout the cooling season and full sun throughout the heating season. It also strongly effects how quickly an overhang will transition from providing full shade to providing full sun as the year progresses from summer to fall to winter. 
    • The width of an overhang as compared to the window must be taken into consideration as well as its depth. If an overhang is only as wide as the window, it will allow direct sun to slant in from the side during every hour of the day except for the brief moment when the sun is directly in front of the window (Figure 14 at the end of this section illustrates this).
    • Online calculators and simplified rules of thumb for overhang sizing can be appropriate, but only if the rule of thumb specifies the latitude, window orientation, height between the top of the window and the bottom of the overhang, and the climate for which the rule is intended. Any rule of thumb should be based on hourly heat gain modeling analyses.

    The National Renewable Energy Laboratory has provided reliable overhang sizing guidance for numerous locations across the U.S. in its document Solar Radiation Data Manual for Buildings. The guidance is designed to fully shade south-facing windows during the cooling season and provide full sun during the heating season. Recommendations are based on both latitude and local climate (e.g. in very warm climates, the sizing is biased heavily toward more shading for a greater part of the year). The guidance is provided as proportional values for overhang depth and height of overhang above the window (Figure 12). Note that it does not provide recommendations for overhang width. This can be determined using shading visualization programs or using the rules of thumb provided later in this section.

    Figure 12. The Solar Radiation Data Manual for Buildings provides window overhang sizing guidance for 239 locations across the U.S.; this example is for Boulder, CO. (Source: NREL 1995)

     

    By multiplying the proportional values by the height of the actual window to be installed, the dimensions for a specific installation can be obtained. For example, if sizing an overhang for a south-facing window in Boulder, CO, the values in Figure 12 can be used. If the glass in the window unit measures 36 inches from top to bottom, each value in the figure would be multiplied by 36. Once multiplied, the window height dimension in the figure would be, of course, 36 inches (36 x 1.000). The depth of the overhang would be 19 1/4 inches (36 x 0.534). This would be measured horizontally from the glass to the end of the overhang, including gutters, etc. Note that the horizontal measurement should be from the glass, not from the window frame or from the wall. The vertical height between the top of the glass and the bottom of the overhang would be 11 1/2 inches (36 x 0.321). If the overhang is slanted downward, this measurement should be made vertically from the top of the glass to the lowest part of the overhang (i.e. the measurement should be vertical, made to an imaginary horizontal line that is level with the low end of the overhang). Neither the overhang depth nor the height dimension should be measured on a slant; they are measured exactly level and plumb (horizontal and vertical). 

    Free, web-based overhang sizing and analysis tools are also available, such as this suite of solar analysis tools.

    To be effective for summer shading on southeast-, southwest-, due east-, and due west-facing glazing, horizontal overhangs may need to be deeper than for south-facing glazing. Porches, second-story decks, and pergolas can provide the deep overhang needed to protect east- and west-facing windows for most of the day. However, deep horizontal shading over east- and west-facing windows will increase shading in both summer and winter; they do not provide the advantage of wintertime heat gain the way properly sized overhangs for south-facing windows can. East-and west-facing windows can be difficult to optimize for both summer and winter performance. One approach to overhang sizing for east- or west-facing windows is to simply use the same size overhangs as south-facing windows, then incorporate interior or exterior operable shades or shutters to make up for the lack of shading provided during the earlier and later parts of the day.

    Figure 13 shows the difference between a large overhang such as a second-story deck and a smaller overhang when shading a west-facing window. Note how the window with the smaller overhang begins to receive direct sunlight by 2pm, while the window with the larger overhang doesn’t receive full sun until nearly 5pm. 

     

    Figure 13. The 8-foot-deep west-facing overhang on the left provides much better shading late in the day than the 2-foot-deep overhang on the right (results shown for west-facing window, late summer, 36N latitude). (Courtesy of PNNL)

     

    Overhangs should extend well past the sides of the window widthwise, or the window will not be fully shaded when the sun is shining at an angle to the window (Figure 14). Overhangs for south-facing windows should extend widthwise on both sides of the window as shown in Figure 14, but east- and west-facing windows may only need to extend widthwise in one direction (Figure 13 illustrates this for a west-facing window). When viewing a west-facing overhang from the outside, the overhang should extend widthwise to the right (toward the south), and on an east face it should extend widthwise to the left (also toward the south).

     

    Figure 14. The overhang on the left is much wider than the window, allowing it to provide better shade throughout the day than the overhang on the right, which is only the width of the window (results shown for south-facing window, late summer, 2pm, 36N latitude). (Courtesy of PNNL)

     

    The amount of width-extension required depends on the height of the window and how far above the window the overhang is. The greater the dimension from the bottom of the window to the bottom of the overhang, the wider the overhang should be. A simple rule of thumb is to try to size the width of the extension on each side of a south-facing window to be at least equal to the height from the bottom of the window to the bottom of the overhang. For example, a 3 foot by 3 foot window with an overhang that is 0.5 feet above the window would have an overhang with a total width of about 10 feet (3 feet of window width, plus 3.5 feet of width extension on either side). Even at this width sunlight will outflank the overhang in the earlier and later parts of the day. On an east- or west-facing window the width extension should be at least 0.5 times the height from the bottom of the window to the bottom of the overhang at lower latitudes (e.g. 30N), about 0.75 times this dimension at higher latitudes (e.g. 45N), and about 1 times this dimension at very high latitudes (e.g. 60N, if shading is desired at all).  

     

    Vertical Shading Elements

    Once a window with horizontal shading begins to receive direct sun, another form of shading is needed to supplement the overhang. For a shorter overhang, a simple interior shade such as roller blinds may work well. For deeper overhangs such as a porch roof, additional options are possible such as porch shutters, porch curtains, vertical trellises, hanging porch plants, or external landscaping. Even a simple porch screen will reduce solar gains significantly. Figure 15 shows an example of full-coverage porch shutters providing shade from low-angle sunlight while allowing airflow through the porch.

     

    Figure 15. These folding louvered porch doors provide effective shade from low-angle western sunlight and can open for views; the photovoltaic panels overhead allow in filtered natural light. (Source: DOE 2007)

     

     

    Vertical side-shading (as opposed to vertical shading in front of a window) offers another suite of shading options, such as wall fins. Side-fin shading can impede views significantly and only provides moderate protection in most orientations during the summer. Even on east- and west-facing windows, vertical side-shading generally performs no better than well-designed horizontal shading, but provides worse views, less protection from rain, and less solar heat gain in winter (Figure 16). While this type of shading can supplement other shading types on all orientations, it is generally only recommended for north-facing windows. North-facing doors and windows only receive side-angled sunlight from the east and west, so side fins can be an effective stand-alone shading system in this application.

     

    Figure 16. The 2-foot overhang on the left performs better than the 2-foot vertical fin on the right for providing shade in the summer and solar heat gain in the winter (results shown for west-facing window, 2pm, 36N latitude). (Courtesy of PNNL)

     

     

    Window Attachments

    See the Window Attachments for Solar Control and Energy Efficiency guide for in-depth information on utilizing window attachments for shading. Window attachments include interior and exterior products that are installed over windows, doors, or skylights in both residential and commercial buildings. Interior attachments include blinds (Figure 17), shades, drapes, shutters, and surface-applied films.  Exterior products include roller shades, shutters, solar screens, and awnings.  Attachments also include both interior and exterior storm windows. Window attachment products can offer a variety of benefits to homeowners, including solar control and energy savings. Some of the greatest advantages of many window attachments are operability, flexibility, potential for automation, and the ability fully shade the entire window regardless of the sun’s position in the sky.

     

    Figure 17. Light filtering pleated blinds provide cooling savings in summer by blocking and reflecting sunlight, while allowing some diffuse daylight to pass through. (Source: AERC 2023)

     

     

    Window attachments are now rated for energy efficiency in a similar manner to the ratings provided for new windows. The Attachments Energy Rating Council (AERC) is an independent, non-profit rating council that provides accurate and credible information about the energy performance of window attachment products.

    Figure 18 shows an example AERC product label. The higher the rating, the better the attachment performs. The AERC rating can be used to compare products by using the product search feature on the AERC website.

     

    Figure 18.  The Attachment Energy Rating Council label provides cool and warm climate energy performance ratings for tested window attachment products and reports the product’s U-factor, solar heat gain coefficient, visible transmittance, and air leakage (Source:  AERC 2023).

     

     

    In addition to AERC’s rating information, the U.S. Department of Energy (DOE) has developed a window attachments selection tool, located on the Efficient Window Coverings (EWC) website. This tool helps provide guidance on the best window attachment solution for your situation. Figures 19 and 20 show the various types of attachments included on the EWC website.

    Figure 19.  The Efficient Window Coverings website identifies seven categories of exterior window shading attachments. (Source: EWC 2023)

     

     

    Figure 20.  The DOE Efficient Window Coverings website identifies twelve categories of interior window shading attachments (Source: EWC 2023)

     

    Reducing Solar Heat Gain through Skylights

    Skylights tend to admit a large amount of solar heat during the summer season while losing heat in winter. In new construction, attempt to eliminate or minimize skylights in the design. If the building must have skylights, then low-SHGC properties become extremely important. Interior shading systems similar to those used for windows are available for skylights as well.

    One alternative to skylights is to use north- or south-facing clerestory windows, as shown in Figure 21. Clerestory windows, especially if oriented to the north, allow diffuse daylight during most of the day, only receiving direct-beam sunlight near sunrise and sunset in summer. On the other hand, a skylight will admit direct-beam solar radiation into a home all day. South-facing clerestories with proper overhangs can provide fairly even diffuse light in summer and uneven (but interesting) direct light and heat in winter. Figure 20 shows a south-facing clerestory window in winter.

    Figure 21. Clerestory windows bring light in from above, reflecting it off of surfaces, making it more appealing than the direct light that comes from skylights (Source: FSEC).

     

     

    How to Select Shading and Solar Control Systems for Windows and Skylights

    1. Determine window orientation (N, E, W, S, NE, NW, SE, SW, or skylight) and climate zone (see Climate tab).
    2. For new construction, select ENERGY STAR windows and skylights based on your climate. For climates with significant heating loads in winter, consider windows with higher SHGC for south-facing windows. See the Climate tab.
    3. Select a shading system or combination based on the table below.
      1. Combine shading technologies as appropriate, with at least one operable technology per window (e.g., interior or exterior roller shutters, roller screens, roller shades, cellular shades, Roman shades, curtains, Bahama shutters, or traditional hinged shutters). Fixed shading systems can rarely be designed to provide optimal shading, diffuse light, heat gain, privacy, and ventilation through all times of the day and year.
      2. When selecting shading systems, consider performance in both summer and winter, maintenance, convenience, control and automation, resistance to high winds, view preservation, airflow through the window, diffuse natural light performance, privacy, cost, and aesthetics.
      3. For new construction, pre-wire above windows to enable motorized and automated shading systems.
      4. Utilize the Attachments Energy Rating Council, Efficient Window Coverings, and ENERGY STAR Storm Windows websites to compare products.

     

    Table 2 below provides a summary of shading systems, noting appropriate applications for each type of device.

    Table 2. Window Shading Options
    Shading System 
    Best Application/Orientation
    Comments
    Windows, Storm Windows, and Window Films
       
    Low-SHGC Window N, E, W, Skylight In addition to E-W, also appropriate for south-facing windows in warm-hot climates. Low-SHGC windows will increase heating needs in winter. Use the ENERGY STAR climate-specific guidance for target SHGC values. See the Climate tab of this guide. Check the ENERGY STAR product finder to compare products.
    Low-SHGC Storm Window N, E, W, Skylight Appropriate for retrofits only. In addition to E-W, also appropriate for south-facing windows in warm-hot climates. Low-SHGC windows will increase heating needs in winter. Use the ENERGY STAR climate-specific guidance for target SHGC values. See the Climate tab of this guide. Use the ENERGY STAR product finder to find certified products. Check the AERC Warm Climate Rating and SHGC to compare products.
    Standard Storm Windows S, N Appropriate for retrofits only. Provides little solar control but increases U-value. Most appropriate for south- and north-facing windows in cool-cold climates. Will not perform as well as low-E storm windows.
    Window Films E, W, Skylight Appropriate for retrofits only. In addition to E-W, also appropriate for south- and north-facing windows in warm-hot climates. Target low SHGC. Films may increase heating needs in winter. May alter view and reduce daylighting. Ensure film is compatible with existing window.
    Exterior Attachments and Architectural Shading
       
    Exterior Insect Screens (Fixed) Any Choose removable screens to allow removal in winter for better view and solar gains. Will reduce airflow for breeze. Choose UV-resistant material.
    Exterior Roller Solar Screens E, W Can be used in any orientation and adjusted based on needs. Allows view but may block less heat than solid shading. Conducive to automatic control. Will reduce airflow for breeze. Choose UV-resistant material. Check the AERC Warm Climate Rating and SHGC to compare products.
    Exterior Roller Shutters E, W Can be used in any orientation and adjusted based on needs but will block view. Conducive to automatic control. Choose hurricane-rated shutters in high-wind areas.  Check the AERC Warm Climate Rating and SHGC to compare products.
    Traditional Shutters (French door-style) E, W, N Can be used in any orientation and adjusted based on needs. Louvers allow views while blocking direct sun. Can act as vertical fins if left half-open. Choose hurricane-rated shutters in high-wind areas. If louvered, can allow natural ventilation through open windows.
    Bahama Shutters E, W In addition to E-W, also appropriate for south- and north-facing windows due to operability and potential use as a horizontal overhang. Choose hurricane-rated shutters in high-wind areas. Louvers allow view and natural ventilation through open windows.
    Awnings S, E, W May block view from upper portion of window. May not block side-angle sunlight. Check the AERC Warm Climate Rating and SHGC to compare products.
    Window Overhangs S, E, W Properly sized for a given orientation, provides excellent summer shade while allowing winter sun. Allows full view and access to breeze. On east and west, overhangs may need to be deeper, and another form of shading such as roller shades may be needed.
    Roof Eaves S, E, W Properly sized, provides excellent summer shade while allowing winter sun. Allows full view and access to breeze. Also protects windows and siding from rain. On east and west, roof overhang may need to be deeper, and another form of shading such as roller shades may be needed.
    Deep Overhangs (porch roof, second story deck) SE, SW, E, W Appropriate for south-facing windows in hot climates where solar gain in winter is not important. Allows partial view and access to breeze.
    Pergolas or Horizontal Trellises SE, SW, E, W Appropriate for south-facing windows in hot climates where solar gain in winter is not important. Allows partial view and access to breeze. Allows more daylight than porch roof or deck.
    Vertical Trellises E, W, NE, NW If deciduous vines are used, will allow more light and heat in in winter. Can impede view. Some vines are destructive to wall structures, and all vines will hold moisture that can damage a wall. Ensure a buffer space is incorporated between trellises and walls, and select non-destructive vines.
    Fins N, NE, NW Can impede view.
    Landscape Shading
       
    Trees (high canopy, close to house) S, SE, SW, Skylight Use deciduous trees to allow solar gain in winter. Avoid shading solar panels. Allows view and access to breeze.
    Trees (low canopy, close to house) E, W In addition to E-W, also appropriate for NE, NW. May impede view.
    Trees (large, farther away from house) E, W Maintains view and access to breeze. Also appropriate for NE, NW.
    Shrubs E, W Can be appropriate for north if grown vertically to act as side fins. Also appropriate for NE, NW. May impede view.
    Interior Attachments
       
    Interior Solar Screens E, W, Skylight Can be used in any orientation. Preserves view but may not provide as much shade and glare protection as other options. Conducive to automatic control.  Will reduce airflow for breezes. Check the AERC Warm Climate Rating and SHGC to compare products.
    Interior Blinds E, W, Skylight Can be used in any orientation and adjusted to allow full view, full shade, or partial view and partial shade. Conducive to automatic control.  Check the AERC Warm Climate Rating and SHGC to compare products.
    Interior Roman Shades and Curtains E, W Can be used in any orientation and adjusted based on needs but will block views when providing shade. Some models can provide diffuse daylight. Can offer some insulating value in winter. Conducive to automatic control. Will mostly block airflow for breeze.   Check the AERC Warm Climate Rating and SHGC to compare products.
    Interior Cellular Shades E, W, Skylight Can be used in any orientation and adjusted based on needs but will block view when providing shade. Can provide diffuse daylight or blackout depending on model. Provides insulating value in winter. Conducive to automatic control. Will mostly block airflow for breeze. Check the AERC Warm Climate Rating and SHGC to compare products.
    Interior Roller Shades and Pleated Shades E, W, Skylight Can be used in any orientation and adjusted based on needs but will block view when providing shade. Can provide diffuse daylight or blackout depending on model. Can provide some insulating value in winter. Conducive to automatic control. Will mostly block airflow for breeze. Check the AERC Warm Climate Rating and SHGC to compare products.

     

     

    Success
    Ensuring Success

    Any increase in shading during the cooling season is beneficial, no matter how small. The benefits of shading are greatest on the east and west sides of the house in most climate locations. Simple design steps such as increasing a roof overhang, carefully locating a porch, planning for strategic shade trees, and specifying climate-appropriate ENERGY STAR windows can improve the comfort and energy performance for the life of a home. Avoiding or minimizing unshaded skylights, east-facing windows, and west-facing windows is vital to reducing heat gains for comfort, energy efficiency, and resistance to extreme heat.

    Climate
    Climate

    The approach to managing solar heat gain through windows and skylights should be different for different climates. In cold climates, one can take advantage of solar heat gain to provide much needed heat in winter, but in hot climates, protection from solar heat in summer takes priority.

    In areas with long heating seasons, ensure solar access to the south is not shaded in winter. Horizontal overhangs designed to only provide shade in summer are appropriate for south-facing windows in cold regions. Shading east and west windows is generally still appropriate in cool and cold climates. Allowing solar access to these windows in winter is important, however. Though east- and west-facing windows are less important for winter heat gain than south-facing windows, they can still be a significant source of heat.  Deciduous trees will allow some light and heat gain in winter through east and west-facing windows. Overhangs are more appropriate than deciduous trees for the south side, as trees will still block some solar gain in winter even after the leaves have dropped.

    In low-latitude and hot climate areas (far south), highly effective shading of east and west facing surfaces is of primary importance. Unlike higher latitude regions, at very low latitudes shading north-facing glass becomes important as well, as these windows and doors will receive direct solar radiation in mornings and evenings in the summer. The sunlight on north-facing surfaces will mostly come at a low angle from the east and west, so vertical side-shading of windows is appropriate, such as vertical fins or landscaping. Overhangs will not be very effective on north-facing windows. Horizontal overhangs for south-facing glass are appropriate at low latitudes, as in all locations in the United States as long as the overhangs are properly sized for the local latitude and climate.

    The EPA ENERGY STAR program uses different sets of window performance criteria based on the climate regions shown in Figure 1. Figure 2 shows the U-Factor and SHGC requirements that must be met to be ENERGY STAR qualified. See the ENERGY STAR Residential Windows, Doors, and Skylights webpage as well as the ENERGY STAR Storm Windows webpage for links to the certified products finder.

    Figure 1. ENERGY STAR climate zone map for windows and skylights. (EPA 2022)

     

    Figure 2. ENERGY STAR Climate-Specific Criteria for Windows and Skylights, Version 6.0. (Source: EPA 2022)

     

    The International Code Council (ICC) also provides guidance on window specification depending on climate zone in its building code compliance documents including the International Energy Conservation Code (IECC) and the International Residential Code (IRC). Figure 3 provides the IECC climate zone map that applies to IECC versions 2009, 2012, 2015, and 2018. Figure 4 provides the IECC climate zone map that applies to IECC version 2021. This table provides the maximum U-factor and SHGC allowed by various versions of the IECC. Notes and exceptions apply. Consult your local building code for requirements in your jurisdiction. 

     

    Figure  3. Climate Zone Map from IECC 2009, 12, 15, and 18. (Source: 2012 IECC)

     

    Figure  4. Climate Zone Map from IECC 2021. (Source: 2021 IECC)

     

     

    Training
    Right and Wrong Images
    Image
    The overhang on the left is much wider than the window, allowing it to provide far better shade throughout the day than the overhang on the right, which is only the width of the window (results shown for south-facing window, late summer, 36N latitude).
    The overhang on the left is much wider than the window, allowing it to provide far better shade throughout the day than the overhang on the right, which is only the width of the window (results shown for south-facing window, late summer, 36N latitude).
    Image
    The 8-foot deck/overhang on the left provides better summer shading than the 2-foot extended-width overhang, which performs better than the 2-foot window-width overhang, which performs better than the 2-foot vertical fin (late summer, 36N latitude)
    The 8-foot deck/overhang on the left provides better summer shading than the 2-foot extended-width overhang, which performs better than the 2-foot window-width overhang, which performs better than the 2-foot vertical fin (late summer, 36N latitude)
    Image
    The 2-foot extended-width overhang on the left allows more wintertime solar heat gain to this west-facing window than the 2-foot side fin on the right (results shown for west-facing window, mid-winter, 36N latitude)
    The 2-foot extended-width overhang on the left allows more wintertime solar heat gain to this west-facing window than the 2-foot side fin on the right (results shown for west-facing window, mid-winter, 36N latitude)
    Image
    Right – Horizontal overhangs on this house block sunlight in the summer while allowing it in during winter
    Right – Horizontal overhangs on this house block sunlight in the summer while allowing it in during winter
    Image
    Right – deeply inset entryways and overhangs provide shade to reduce solar heat entry to this building.
    Right – deeply inset entryways and overhangs provide shade to reduce solar heat entry to this building.
    Image
    Right- Landscaping shades the entry on the south west corner of this hot dry climate building.
    Right- Landscaping shades the entry on the south west corner of this hot dry climate building.
    Image
    Right - This house has key features to block heat such as such as tree shading for the west wall and roof, minimized west-facing windows, and a porch roof, floor, and wing walls creating deep architectural overhangs and fins to shade south-facing windows
    Right - This house has key features to block heat such as such as tree shading for the west wall and roof, minimized west-facing windows, and a porch roof, floor, and wing walls creating deep architectural overhangs and fins to shade south-facing windows
    Image
    Wrong - this building provides no overhangs, minimal window shading, and clear window glass resulting in high solar heat gain.
    Wrong - this building provides no overhangs, minimal window shading, and clear window glass resulting in high solar heat gain.
    Image
    Right - This home's windows have protective coverings that are raised to provide shade in good weather and can drop to protect the windows during high wind events.
    Right - This home's windows have protective coverings that are raised to provide shade in good weather and can drop to protect the windows during high wind events.
    Image
    Right – This model home for the Solar Decathlon competition incorporates vertical trellises and retractable exterior blinds to control solar heat gain.
    Right – This model home for the Solar Decathlon competition incorporates vertical trellises and retractable exterior blinds to control solar heat gain.
    Image
    Right - In cooler climates, landscape shading should focus on the east- and west-facing walls, while leaving the south side of the house clear for solar access in winter (well-sized roof overhangs could provide summer shading for the south-facing windows)
    Right - In cooler climates, landscape shading should focus on the east- and west-facing walls, while leaving the south side of the house clear for solar access in winter (well-sized roof overhangs could provide summer shading for the south-facing windows)
    Image
    Right – A deep porch provides shade and keeps sun off sliding glass doors in this Arizona home while artificial turf and xeriscaping minimize irrigation usage.
    Right – A deep porch provides shade and keeps sun off sliding glass doors in this Arizona home while artificial turf and xeriscaping minimize irrigation usage.
    Image
    Right - Window shading is built into the south side of this home and east facing windows have been minimized to reduce heat gain from the summer sun while allowing low winter sun into the home
    Right - Window shading is built into the south side of this home and east facing windows have been minimized to reduce heat gain from the summer sun while allowing low winter sun into the home
    Compliance

    Compliance

    The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

    EPA ENERGY STAR label for windows and skylights

    See the Climate tab for information on ENERGY STAR requirements for windows and skylights.

     

    ENERGY STAR Single-Family New Homes, Version 3/3.1/3.2

    The ENERGY STAR Reference Design Home is the set of efficiency features modeled to determine the ENERGY STAR ERI Target for each home pursuing certification. The requirements for the Reference Design Home, including the fenestration (windows) requirements, are listed in Exhibit 1 of the National Program Requirements document. They are not mandatory but can be traded off with other measures to achieve the ENERGY STAR ERI Target.

     

    DOE Zero Energy Ready Home Version 1 and Version 2

    Exhibit 1 Mandatory Requirements.
    Version 1: Exhibit 1, Item 2) Fenestration shall meet or exceed ENERGY STAR requirements.

    Version 2: Exhibit 1, Item 3) DOE is monitoring ENERGY STAR specifications and plans to adopt them in a future version update.

     

    2009-2021 IECC and IRC Window U-Factor Requirements Table

    The maximum U-Factor and Solar Heat Gain Coefficient (SHGC) requirements for fenestration (windows) and skylights in new homes, as listed in the 2009, 2012, 2015, 2018, and 2021 IECC and IRC, can be found in this table.

     

    2009 International Energy Conservation Code (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.

     

    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.

     

    2015 and 2018 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.

     

    2021 IECC

    For 2021 complying by the U-factor method, the fenestration U-factor can be no higher than 0.30 in climate zones 3 through 8, no higher than 0.4 in climate zone 2 and no higher than 0.5 in climate zones 0 and 1. The skylight U-factor can be no higher than 0.55 in climate zones 3 -8, no higher than 0.65 in climate zone 2 and no higher than 0.75 in climate zones 1 and 2. The SHGC can be no more than 0.25 in climate zones 0 -3, no more than 0.4 in climate zones 4 and 5 (Except marine climate areas where there is no SHGC requirement). There is not an SHGC requirement in climate zones 6 and 7. Note that other code compliance methods have some flexibility. The R-value method of compliance lets the average fenestration to meet the requirements that allows, for example, a higher SHGC on south side orientations and lower on east and west facades, although it is rare for builders to do this. Other compliance methods such as UA alternative compliance, performance compliance and compliance by the ERI method allow trade-offs among envelope and/or other features.

     

    Retrofit:  2009201220152018,  and 2021 IECC

    Section R101.4.3 (in 2009 and 2012). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)

    Chapter 5 (in 2015, 2018, 2021). The provisions of this chapter shall control the alteration, repair, addition, and change of occupancy of existing buildings and structures.

     

    2009 International Residential Code (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 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 and 2018 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.

     

    Retrofit:  2009201220152018,  and 2021 IRC

    Section R102.7.1 Additions, alterations, or repairs. Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with the requirements of this code, unless otherwise stated. (See code for additional requirements and exceptions.)

    Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.

    Retrofit
    Existing Homes

    The simplest approach to solar control for windows in a retrofit situation is to use window attachments as described in the Window Attachments for Solar Control and Energy Efficiency guide, as well as the Window Attachments section on the Description tab of this guide. See Figure 1 for a list of interior attachment types and Figure 2 for exterior attachments. See the Attachments Energy Rating Council (AERC) and the Efficient Window Coverings (EWC) websites. See also the Low-E Exterior Storm Windows guide, and the Interior Storm Windows and Panels guide for information on high-performance storm window retrofits.

    Figure 1.  The Window Coverings and Attachments website divides interior shading attachments into 12 categories as shown above. (Source: EWC 2023

     

    Figure 2.  The Window Coverings and Attachments website divides exterior shading attachments into 7 categories as shown above. (Source: EWC 2023

     

    More

    More Info.

    Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

    References and Resources*
    Author(s)
    National Fenestration Rating Council
    Organization(s)
    NFRC
    Publication Date
    Description
    Database from the National Fenestration Rating Council providing a directory of NFRC-certified window products searchable by manufacturer, product type, CPD number, or various NFRC label specifications.
    Author(s)
    National Fenestration Rating Council
    Organization(s)
    NFRC
    Publication Date
    Description
    Database of NFRC rated windows.
    Author(s)
    Attachments Energy Rating Council
    Organization(s)
    AERC
    Publication Date
    Description
    Website developed by the Attachments Energy Rating Council to provide consumers with credible, relevant, and comparable information about window attachments and their performance.
    Author(s)
    Lawrence Berkeley National Laboratory
    Organization(s)
    Building Green,
    DOE,
    LBNL
    Publication Date
    Description
    Website sponsored by DOE to provide consumers with intelligent and unbiased guidance on the best window covering for your climate, your needs, and your windows.
    Author(s)
    Energy Saver
    Organization(s)
    U.S. Department of Energy
    Publication Date
    Description
    Web page providing an overview of window coverings such as blinds, shades, shutters, films, and storm windows.
    Author(s)
    Florida Solar Energy Center
    Organization(s)
    University of Central Florida
    Publication Date
    Description
    Web article providing information on how to reduce solar gains through windows.
    Author(s)
    Don Prowler and Joseph Bourg
    Organization(s)
    Whole Building Design Guide
    Publication Date
    Description
    Article providing fundamental information and recommendations for shading windows for energy savings.
    Author(s)
    Curcija Charlie,
    Yazdanian Mehry,
    Kohler Christian,
    Hart Robert,
    Mitchell Robin,
    Vidanovic Simon
    Organization(s)
    Lawrence Berkeley National Laboratory,
    LBNL
    Publication Date
    Description
    Report describing a comprehensive analysis on energy savings from multiple types of shading devices in multiple climate zones.
    Author(s)
    Cort Katherine A,
    McIntosh Joshua A,
    Sullivan Greg P,
    Ashley Travis A,
    Metzger Cheryn E,
    Fernandez Nicholas
    Organization(s)
    Pacific Northwest National Laboratory,
    PNNL,
    Efficiency Solutions
    Publication Date
    Description
    DOE-sponsored report describing the experimental design and results of testing the energy performance of Hunter Douglas double-cell cellular shades under various control schemes in the Pacific Northwest National Laboratory’s Lab Homes.
    Author(s)
    Walter Hunt,
    Katherine Cort
    Organization(s)
    Pacific Northwest National Laboratory
    Publication Date
    Description
    DOE-sponsored report describing the experimental setup and results of field studies on using exterior fabric shading attachments to reduce solar heat gain, reduce glare, and improve comfort.
    Author(s)
    Bhandari Mahabir,
    Kunwar Niraj,
    Gehl Anthony,
    Curcija Charlie
    Organization(s)
    Oak Ridge National Laboratory,
    ORNL,
    Lawrence Berkeley National Laboratory,
    LBNL
    Publication Date
    Description
    DOE-sponsored report describing a study investigating the energy savings potential of cellular shades in homes.
    *For non-dated media, such as websites, the date listed is the date accessed.
    Contributors to this Guide

    The following authors and organizations contributed to the content in this Guide.

    Last Updated

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