External Shading Devices in Commercial Buildings

Transcription

1 External Shading Devices in Commercial Buildings The Impact on Energy Use, Peak Demand and Glare Control John Carmody and Kerry Haglund Center for Sustainable Building Research University of Minnesota The Alcoa Building in Pittsburgh, PA uses exterior shading devices. Architect: The Design Alliance Architects; Photo: Courtesy of Viracon Sponsored by Air Movement and Control Association International 30 West University Drive Arlington Heights, IL

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3 External Shading Devices in Commercial Buildings The Impact on Energy Use, Peak Demand and Glare Control John Carmody and Kerry Haglund Center for Sustainable Building Reserach, University of Minnesota Contents Acknowledgements...2 Introduction...3 Minneapolis, Minnesota East Orientation Moderate Window Area...6 East Orientation Large Window Area...7 South Orientation Moderate Window Area...8 South Orientation Large Window Area...9 West Orientation Moderate Window Area...10 West Orientation Large Window Area...11 Houston, Texas East Orientation Moderate Window Area...24 East Orientation Large Window Area...25 South Orientation Moderate Window Area...26 South Orientation Large Window Area...27 West Orientation Moderate Window Area...28 West Orientation Large Window Area...29 Chicago, Illinois East Orientation Moderate Window Area...12 East Orientation Large Window Area...13 South Orientation Moderate Window Area...14 South Orientation Large Window Area...15 West Orientation Moderate Window Area...16 West Orientation Large Window Area...17 Phoenix, Arizona East Orientation Moderate Window Area...30 East Orientation Large Window Area...31 South Orientation Moderate Window Area...32 South Orientation Large Window Area...33 West Orientation Moderate Window Area...34 West Orientation Large Window Area...35 Washington, DC East Orientation Moderate Window Area...18 East Orientation Large Window Area...19 South Orientation Moderate Window Area...20 South Orientation Large Window Area...21 West Orientation Moderate Window Area...22 West Orientation Large Window Area...23 Los Angeles, California East Orientation Moderate Window Area...36 East Orientation Large Window Area...37 South Orientation Moderate Window Area...38 South Orientation Large Window Area...39 West Orientation Moderate Window Area...40 West Orientation Large Window Area...41 Appendix...42 Air Movement and Control Association International ( Page 1

4 Acknowledgments The material in this report was prepared by John Carmody and Kerry Haglund from the Center for Sustainable Building Research at the University of Minnesota. The information in this publication is based on computer simulations done at Lawrence Berkeley National Laboratory for the U.S Department of Energy Windows and Glazing Program. The source of some of the text and data in this publication is the book, Window Systems for High Performance Commercial Buildings by John Carmody, Steve Selkowitz, Eleanor S. Lee, Dariush Arasteh and Todd Willmert (Norton, 2004). More extensive results are available in the book, Window Systems for High Performance Buildings, and at the web site umn.edu. The roster of AMCA Committee members who guided the development include the Committee Chair Roger Lichtenwald, American Warming & Ventilating; Randall Geedey, The Airolite Company; Vince Kreglewicz, Arrow United Industries; Steve Lynch, Construction Specialties, Inc.; Mike Watz, Greenheck Fan Corp.; Jo Reinhardt, Industrial Louvers, Inc.; Michael McGill, M.W. McGill & Associates Ltd., Dane Carey, NCA Manufacturing; Mike Almaguer, Pottorff; James Livingston, Ruskin Company, and Timothy Orris, AMCA International, Inc. For further information, contact: Air Movement and Control Association International 30 West University Drive Arlington Heights, IL Copyright 2006 Regents of the University of Minnesota, Twin Cities Campus, College of Design. All rights reserved. Page 2 Air Movement and Control Association International (

5 Introduction Benefits of External Shading Devices Exterior shading devices such as overhangs and vertical have a number of advantages that contribute to a more sustainable building. First, exterior shading devices result in energy savings by reducing direct solar gain through windows. By using exterior shading devices with less expensive glazings, it is sometimes possible to obtain performance equivalent to unshaded higher performance glazings. A second benefit is that peak electricity demand is also reduced by exterior shading devices resulting in lower peak demand charges from utilities and reduced mechanical equipment costs. ally, exterior shading devices have the ability to reduce glare in an interior space without the need to lower shades or close blinds. This means that daylight and view are not diminished by dark tinted glazings or blocked by interior shades. With exterior shading devices, glare control does not depend on user operation. Using This Publication This publication shows the impact of external shading devices on the energy use, peak demand, and glare conditions in commercial office buildings. This publication is intended to help the designer quickly narrow the range of possibilities and understand the approximate impacts in commercial office buildings in order to provide general guidance during early stages of design. If there is more time and budget, this can be followed by a more detailed computer simulation of the specific building and the design conditions. In the following sections, results are presented for six cities with differing climates: Minneapolis, Chicago, Washington DC, Houston, Phoenix and Los Angeles. Within each climate, results are shown for east, south, and westfacing orientations. The north orientation is not shown since the impacts of external shading devices are small. Within each orientation, there are results for both moderate (WWR=0.30) and a large (WWR=0.60) window areas (WWR is the windowtowall ratio). For each set of conditions, there are six window types and five shading conditions. As shown in Figure 1, the five shading conditions include: (), vertical (), (), deep overhang (), and with (f). For each location, orientation and window area, there is a table summarizing the impacts of external shading devices. An example of one of these tables is shown in Table 1 for a perimeter office zone in Houston, Texas with a south facing orientation and large glazing area. For a given glass type, there are five lines of data one for each shading condition. The Energy column shows the actual energy use for each shading condition and the Energy % Save shows the percent savings compared to the unshaded case (). Similarly, the Peak column shows actual peak demand and the Peak % Save shows the percent savings compared to the unshaded case (). The Glare column shows the weighted glare index for each shading condition and the Glare % Red. shows the percent glare reduction compared to the unshaded case (). In comparing different sections of the publication, it is clear that the impacts of external shading devices are different depending on the building location, the window orientation, and window size. In addition, as shown in Table 1, the type of glazing and shading device used also impact the results. FIGURE 1 Air Movement and Control Association International ( Page 3

6 Energy Use Impacts and shading condition, Table 1 the percent savings compared to the Regarding energy use, the percent savings resulting from using a varies from 25.6% when applied to a clear double glazed window compared to 11.3% when applied to a triple glazed lowe window. The actual energy savings from the deep overhang in the two cases ranges from 52 kbtu per square foot when applied to a clear double glazed window to 15 kbtu per square foot when applied to a triple glazed lowe window. They key to this difference is that clear double glazing has a Solar Heat Gain Coefficient (SHGC) of 0.60 meaning that 60% of the solar heat gain is transmitted through the glass while 40% is blocked, while triple glazed lowe glazing has an SHGC of 0.22 meaning only 22% of the solar heat gain is transmitted and 78% is blocked by the glass. In effect, the higher performance glazing is already diminishing the solar gain quite a bit before the external shading device is applied. The overhang still makes a substantial difference in both cases but the value and payback varies depending on the conditions. Figure 2 illustrates this pattern for all the glazings and shading devices in Table 1. As the SHGC of the glazing improves, the absolute value of savings from the external shading device is smaller. This situation also presents an interesting design alternative it is possible to obtain equivalent performance to a low solar heat gain glazing with device by using external shading devices with glazings that have higher solar heat gain characteristics. Peak Demand Impacts The impact of external shading devices on peak demand follows a similar pattern to the impact on energy use. Table 1 shows that the percent savings resulting from using a varies from 44.1% when applied to a clear double glazed window compared to 18.8% when applied to a triple glazed lowe window. The actual peak demand reduction from the in the two cases ranges from 5.03 kw per square foot when applied to a clear double glazed window to 1.19 kw per square foot when applied to a triple glazed lowe window. As with energy use, the overhang still makes a substantial difference on peak demand in both cases but the value and payback varies depending on the conditions. Figure 3 illustrates this pattern for all the glazings and shading devices in Table 1. TABLE 1 IMPACT OF EXTERIOR SHADING HOUSTON, TX South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical 3.36 Page 4 Air Movement and Control Association International (

7 FIGURE 2 FIGURE 3 25 ANNUAL ENERGY USE HOUSTON, TX South Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND HOUSTON, TX South Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Glare Impacts The impact of exterior shading devices on glare in interior spaces is also illustrated by Table 1. The glare index is calculated at a point five feet from the window for a person facing the side wall. A lower index is better. A glare index of 10 is considered just perceptible, an index of 16 is just acceptable and an index of 22 is just uncomfortable. Unlike energy use and peak demand, glare reduction appears to be similar in percentage and amount for all glazing types. The greatest glare reduction occurs with a combination of a with vertical. The percent savings in glare index resulting from using a with is 35.1% when applied to a clear double glazed window compared to 40.8% when applied to a triple glazed lowe window. The glare index is reduced from 15 to 10 when the with are applied to a clear double glazed window. The glare index is reduced from 14 to 8 when applied to a triple glazed lowe window. A key advantage of external shading devices is that they can provide glare reduction without the need to lower shades or close blinds. This means that daylight and view are not diminished by dark tinted glazings or blocked by interior shades. With exterior shading devices, glare control does not depend on user operation. External shading devices can play an important role in creating more sustainable buildings with less energy use and peak demand as well as improved glare conditions for the building occupants. The AMCA publication and other resources are now available to assist designers in optimizing façade design. References Carmody, John, External Shading Devices in Commercial Buildings: The Impact on Energy Use, Peak Demand and Glare Control. Published by Air Movement and Control Association International (AMCA), 30 West University Drive, Arlington Heights, Illinois Phone: Web: Carmody, J., E. Lee, S. Selkowitz, D. Arasteh, and T. Willmert, Window Systems for High Performance Buildings, W.W. Norton & Company, Commercial Windows Web Site: Air Movement and Control Association International ( Page 5

8 Minneapolis, Minnesota East Orientation Moderate Window Area page show the impact of external shading devices on an eastfacing facade with moderate window area in a commercial office building in Minneapolis, Minnesota. device used. Six typical commercial heat gain coefficients are analyzed. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING MINNEAPOLIS, MN East Orientation Moderate Window Area (WWR=0.30) Note: All cases are eastfacing with a 0.30 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE MINNEAPOLIS, MN East Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND MINNEAPOLIS, MN East Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 6 Air Movement and Control Association International (

9 Minneapolis, Minnesota East Orientation Large Window Area shading devices on an eastfacing facade with a large window area Minneapolis, Minnesota. device used. Six typical commercial heat gain coefficients are analyzed. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING MINNEAPOLIS, MN East Orientation Large Window Area (WWR=0.60) Note: All cases are eastfacing with a 0.60 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE MINNEAPOLIS, MN East Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND MINNEAPOLIS, MN East Orientation Large Window Area (WWR=0.60) 20 1 kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 7

10 Minneapolis, Minnesota South Orientation Moderate Window Area shading devices on an southfacing facade with moderate window area Minneapolis, Minnesota. device used. Six typical commercial heat gain coefficients are analyzed. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING MINNEAPOLIS, MN South Orientation Moderate Window Area (WWR=0.30) Note: All cases are southfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE MINNEAPOLIS, MN South Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND MINNEAPOLIS, MN South Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 8 Air Movement and Control Association International (

11 Minneapolis, Minnesota South Orientation Large Window Area shading devices on an southfacing facade with a large window area Minneapolis, Minnesota. device used. Six typical commercial heat gain coefficients are analyzed. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING MINNEAPOLIS, MN South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE MINNEAPOLIS, MN South Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND MINNEAPOLIS, MN South Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 9

12 Minneapolis, Minnesota West Orientation Moderate Window Area shading devices on an westfacing facade with moderate window area Minneapolis, Minnesota. device used. Six typical commercial heat gain coefficients are analyzed. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING MINNEAPOLIS, MN West Orientation Moderate Window Area (WWR=0.30) Note: All cases are westfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE MINNEAPOLIS, MN West Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND MINNEAPOLIS, MN West Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 10 Air Movement and Control Association International (

13 Minneapolis, Minnesota West Orientation Large Window Area shading devices on an westfacing facade with a large window area Minneapolis, Minnesota. device used. Six typical commercial heat gain coefficients are analyzed. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING MINNEAPOLIS, MN West Orientation Large Window Area (WWR=0.60) Note: All cases are westfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE MINNEAPOLIS, MN West Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND MINNEAPOLIS, MN West Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 11

14 Chicago, Illinois East Orientation Moderate Window Area shading devices on an eastfacing facade with moderate window area Chicago, Illinois. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING CHICAGO, IL East Orientation Moderate Window Area (WWR=0.30) Note: All cases are eastfacing with a 0.30 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE CHICAGO, IL East Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND CHICAGO, IL East Orientation Moderate Window Area (WWR=0.30) kbtu/sfyear B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 12 Air Movement and Control Association International (

15 Chicago, Illinois East Orientation Large Window Area page show the impact of external shading devices on an eastfacing facade with large window area in a commercial office building in Chicago, Illinois. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING CHICAGO, IL East Orientation Large Window Area (WWR=0.60) Note: All cases are eastfacing with a 0.60 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE CHICAGO, IL East Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND CHICAGO, IL East Orientation Large Window Area (WWR=0.60) kbtu/sfyear B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 13

16 Chicago, Illinois South Orientation Moderate Window Area shading devices on an southfacing facade with moderate window area Chicago, Illinois. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING CHICAGO, IL South Orientation Moderate Window Area (WWR=0.30) Note: All cases are southfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE CHICAGO, IL South Orientation Moderate Window Area (WWR=0.30) PEAK ELECTRICITY DEMAND CHICAGO, IL South Orientation Moderate Window Area (WWR=0.30) kbtu/sfyear B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 14 Air Movement and Control Association International (

17 Chicago, Illinois South Orientation Large Window Area shading devices on an southfacing facade with a large window area Chicago, Illinois. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING CHICAGO, IL South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE CHICAGO, IL South Orientation Large Window Area (WWR=0.60) 1 1 PEAK ELECTRICITY DEMAND CHICAGO, IL South Orientation Large Window Area (WWR=0.60) kbtu/sfyear B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 15

18 Chicago, Illinois West Orientation Moderate Window Area shading devices on an westfacing facade with moderate window area Chicago, Illinois. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING CHICAGO, IL West Orientation Moderate Window Area (WWR=0.30) Note: All cases are westfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE CHICAGO, IL West Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND CHICAGO, IL West Orientation Moderate Window Area (WWR=0.30) kbtu/sfyear B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 16 Air Movement and Control Association International (

19 Chicago, Illinois West Orientation Large Window Area shading devices on an westfacing facade with a large window area Chicago, Illinois. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING CHICAGO, IL West Orientation Large Window Area (WWR=0.60) Note: All cases are westfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE CHICAGO, IL West Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND CHICAGO, IL West Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 17

20 Washington, DC East Orientation Moderate Window Area shading devices on an eastfacing facade with moderate window area Washington, DC. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING WASHINGTON, DC East Orientation Moderate Window Area (WWR=0.30) Note: All cases are eastfacing with a 0.30 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE WASHINGTON, DC East Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND WASHINGTON, DC East Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 18 Air Movement and Control Association International (

21 Washington, DC East Orientation Large Window Area page show the impact of external shading devices on an eastfacing facade with a large window area in a commercial office building in Washington, DC. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING WASHINGTON, DC East Orientation Large Window Area (WWR=0.60) Note: All cases are eastfacing with a 0.60 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE WASHINGTON, DC East Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND WASHINGTON, DC East Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 19

22 Washington, DC South Orientation Moderate Window Area shading devices on an southfacing facade with moderate window area Washington, DC. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING WASHINGTON, DC South Orientation Moderate Window Area (WWR=0.30) Note: All cases are southfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE WASHINGTON, DC South Orientation Moderate Window Area (WWR=0.30) PEAK ELECTRICITY DEMAND WASHINGTON, DC South Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 20 Air Movement and Control Association International (

23 Washington, DC South Orientation Large Window Area shading devices on an southfacing facade with a large window area Washington, DC. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING WASHINGTON, DC South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE WASHINGTON, DC South Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND WASHINGTON, DC South Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 21

24 Washington, DC West Orientation Moderate Window Area shading devices on an westfacing facade with moderate window area Washington, DC. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING WASHINGTON, DC West Orientation Moderate Window Area (WWR=0.30) Note: All cases are westfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE WASHINGTON, DC West Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND WASHINGTON, DC West Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 22 Air Movement and Control Association International (

25 Washington, DC West Orientation Large Window Area shading devices on an westfacing facade with a large window area Washington, DC. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING WASHINGTON, DC West Orientation Large Window Area (WWR=0.60) Note: All cases are westfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE WASHINGTON, DC West Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND WASHINGTON, DC West Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 23

26 Houston, Texas East Orientation Moderate Window Area shading devices on an eastfacing facade with moderate window area Houston, Texas. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING HOUSTON, TX East Orientation Moderate Window Area (WWR=0.30) Note: All cases are eastfacing with a 0.30 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE HOUSTON, TX East Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND HOUSTON, TX East Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 24 Air Movement and Control Association International (

27 Houston, Texas East Orientation Large Window Area page show the impact of external shading devices on an eastfacing facade with a large window area in a commercial office building in Houston, Texas. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING HOUSTON,TX East Orientation Large Window Area (WWR=0.60) Note: All cases are eastfacing with a 0.60 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE HOUSTON, TX East Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND HOUSTON, TX East Orientation Large Window Area (WWR=0.60) 20 1 kwh/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 25

28 Houston, Texas South Orientation Moderate Window Area shading devices on an southfacing facade with moderate window area Houston, Texas. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING HOUSTON, TX South Orientation Moderate Window Area (WWR=0.30) Note: All cases are southfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE HOUSTON, TX South Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND HOUSTON, TX South Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 26 Air Movement and Control Association International (

29 Houston, Texas South Orientation Large Window Area shading devices on an southfacing facade with a large window area Houston, Texas. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING HOUSTON, TX South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE HOUSTON, TX South Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND HOUSTON, TX South Orientation Large Window Area (WWR=0.60) 20 1 kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 27

30 Houston, Texas West Orientation Moderate Window Area shading devices on an westfacing facade with moderate window area Houston, Texas. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING HOUSTON, TX West Orientation Moderate Window Area (WWR=0.30) Note: All cases are westfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE HOUSTON, TX West Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND HOUSTON, TX West Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 28 Air Movement and Control Association International (

31 Houston, Texas West Orientation Large Window Area shading devices on an westfacing facade with a large window area Houston, Texas. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING HOUSTON, TX West Orientation Large Window Area (WWR=0.60) Note: All cases are westfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE HOUSTON, TX West Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND HOUSTON, TX West Orientation Large Window Area (WWR=0.60) 20 1 kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 29

32 Phoenix, Arizona East Orientation Moderate Window Area page show the impact of external shading devices on an eastfacing facade with moderate window area in a commercial office building in Phoenix, Arizona. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING PHOENIX, AZ East Orientation Moderate Window Area (WWR=0.30) Note: All cases are eastfacing with a 0.30 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE PHOENIX, AZ East Orientation Moderate Window Area (WWR=0.30) 8.00 PEAK ELECTRICITY DEMAND PHOENIX, AZ East Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 30 Air Movement and Control Association International (

33 Phoenix, Arizona East Orientation Large Window Area page show the impact of external shading devices on an eastfacing facade with a large window area in a commercial office building in Phoenix, Arizona. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING PHOENIX, AZ East Orientation Large Window Area (WWR=0.60) Note: All cases are eastfacing with a 0.60 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE PHOENIX, AZ East Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND PHOENIX, AZ East Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 31

34 Phoenix, Arizona South Orientation Moderate Window Area shading devices on an southfacing facade with moderate window area Phoenix, Arizona. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING PHOENIX, AZ South Orientation Moderate Window Area (WWR=0.30) Note: All cases are southfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE PHOENIX, AZ South Orientation Moderate Window Area (WWR=0.30) 8.00 PEAK ELECTRICITY DEMAND PHOENIX, AZ South Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 32 Air Movement and Control Association International (

35 Phoenix, Arizona South Orientation Large Window Area shading devices on an southfacing facade with a large window area Phoenix, Arizona. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING PHOENIX, AZ South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE PHOENIX, AZ South Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND PHOENIX, AZ South Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 33

36 Phoenix, Arizona West Orientation Moderate Window Area shading devices on an westfacing facade with moderate window area Phoenix, Arizona. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING PHOENIX, AZ West Orientation Moderate Window Area (WWR=0.30) Note: All cases are westfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE PHOENIX, AZ West Orientation Moderate Window Area (WWR=0.30) 8.00 PEAK ELECTRICITY DEMAND PHOENIX, AZ West Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 34 Air Movement and Control Association International (

37 Phoenix, Arizona West Orientation Large Window Area shading devices on an westfacing facade with a large window area Phoenix, Arizona. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING PHOENIX, AZ West Orientation Large Window Area (WWR=0.60) Note: All cases are westfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE PHOENIX, AZ West Orientation Large Window Area (WWR=0.60) PEAK ELECTRICITY DEMAND PHOENIX, AZ West Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 35

38 Los Angeles, California East Orientation Moderate Window Area page show the impact of external shading devices on an eastfacing facade with moderate window area in a commercial office building in Los Angeles, California. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING LOS ANGELES, CA East Orientation Moderate Window Area (WWR=0.30) Note: All cases are eastfacing with a 0.30 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE LOS ANGELES, CA East Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND LOS ANGELES, CA East Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 36 Air Movement and Control Association International (

39 Los Angeles, California East Orientation Large Window Area shading devices on an eastfacing facade with a large window area in a commercial office building in Los Angeles, California. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING LOS ANGELES, CA East Orientation Large Window Area (WWR=0.60) Note: All cases are eastfacing with a 0.60 windowtowall ratio and include daylighting controls. Annual energy use is expressed in kbtu per square foot of floor area within a 15footdeep perimeter zone. Peak demand is expressed in Watts per square foot of floor area within a 15footdeep point 5 feet from the window for a person facing the side wall. A lower index is better. All results were computed using DOE2.1E for a typical office building. of external shading devices. SHGC=solar heat gain coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE LOS ANGELES, CA East Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND LOS ANGELES, CA East Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE s LowE G LowE B LowE B LowE s LowE G LowE Air Movement and Control Association International ( Page 37

40 Los Angeles, California South Orientation Moderate Window Area shading devices on an southfacing facade with moderate window area Los Angeles, California. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING LOS ANGELES, CA South Orientation Moderate Window Area (WWR=0.30) Note: All cases are southfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE LOS ANGELES, CA South Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND LOS ANGELES, CA South Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 38 Air Movement and Control Association International (

41 Los Angeles, California South Orientation Large Window Area shading devices on an southfacing facade with a large window area in a commercial office building in Los Angeles, California. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING LOS ANGELES, CA South Orientation Large Window Area (WWR=0.60) Note: All cases are southfacing with a 0.60 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE LOS ANGELES, CA South Orientation Large Window Area (WWR=0.60) 1 PEAK ELECTRICITY DEMAND LOS ANGELES, CA South Orientation Large Window Area (WWR=0.60) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Air Movement and Control Association International ( Page 39

42 Los Angeles, California West Orientation Moderate Window Area shading devices on an westfacing facade with moderate window area Los Angeles, California. analyzed include (), vertical (), shallow overhang (), (), and with, (f). IMPACT OF EXTERIOR SHADING LOS ANGELES, CA West Orientation Moderate Window Area (WWR=0.30) Note: All cases are westfacing with a 0.30 windowtowall ratio and include daylighting per square foot of floor area within a 15footdeep Watts per square foot of floor area within a 15footdeep computed using DOE2.1E for a typical office building. coefficient, Uvalue=heat transmission in Btu/hrsf f vertical & vertical ANNUAL ENERGY USE LOS ANGELES, CA West Orientation Moderate Window Area (WWR=0.30) 7.00 PEAK ELECTRICITY DEMAND LOS ANGELES, CA West Orientation Moderate Window Area (WWR=0.30) kbtu/sfyr B LowE B LowE LowE G LowE B LowE B LowE LowE G LowE Page 40 Air Movement and Control Association International (