17_Shading%20Requirements_GB_2007-slides

17_Shading Require - Solar Radiation Window Properties Shading Analysis Arch 140 Lecture#17 Tuesday What happens to solar radiation intercepted by

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Solar Radiation, Window Properties & Shading Analysis Arch 140, Lecture #17 Tuesday, March 13, 2007
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What happens to solar radiation intercepted by the earth’s atmosphere? Direct Beam 50% (Diffuse) Solar constant = 430 Btu/hr-ft 2
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1. The Solar Constant 2. Earth’s Movement 3. Location on Earth 4. Surface Tilt & Orientation 5. Weather / Climate Patterns 6. Microclimatic Shading 7. Surface Shading Devices 8. Transmission through Glazing 9. Surface Absorption Solar Modifiers
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South Vertical E, W Vertical Horizontal North Vertical E f e c t o O r i n a (40°NL) Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec S l R d ( B u / y - s q . g ) In summer, horizontal receives 3x south-facing E/W receives more sun in summer than winter
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Horizontal South Vertical (90 º tilt) 60 º tilt 30 º tilt Effect of Tilt (40° NL) Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Solar Radiation (Btu/day-sq.ft glass) Tilting increases winter gain, but effect is bigger in summer
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Solar Geometry Spreadsheet Annual Version Benton’s spreadsheet
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Daily Patterns – South Window Direct Solar Radiation for South-Facing Window 0 50 100 150 200 250 300 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour Solar Radiation (Btu/hr-sf) DEC MAR-SEP JUNE S-facing window receives over 3 times as much sun at noon in winter, than at noon in summer
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Daily Patterns – Horizontal Skylight Direct Solar Radiation for Horizontal Skylight 0 50.0 100.0 150.0 200.0 250.0 300.0 0 1 2 3 4 5 6 7 8 9 1 01 11 21 31 41 51 61 71 81 92 02 12 22 32 4 Hour Solar Radiation (Btu/hr-sf) DEC MAR-SEP JUNE The radiation striking a horizontal skylight represents a cooling liability in most climates
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Daily Patterns – East Window 0 50 100 150 200 250 300 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Hour Solar Radiation (Btu/hr-sf) Direct Solar Radiation for East-Facing Window DEC MAR-SEP JUNE
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Window Properties – Radiant heat exchange OUTDOORS OUTDOORS INDOORS INDOORS Double-glazed window Solar transmittance Inward flowing component of absorbed radiation Absorbed radiation Incident radiation Admitted radiation Admitted = Transmitted + Absorbed/Re-radiated
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National Fenestration Rating Council (NFRC) NFRC's primary goal is to provide accurate information to measure and compare the energy performance of fenestration products. Fenestration: Any opening in a building’s envelope including windows, doors and skylights www.nfrc.org
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NFRC Window Rating System U-Factor Solar Heat Gain Coefficient Visible Light Transmittance Air Leakage NFRC has established a voluntary national energy performance rating and labeling system for fenestration products.
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U-Factor (Btu/hr-ft 2 -°F) U-factor measures how well a product prevents heat from escaping. U-factor ratings for windows generally fall between 0.20 and 1.20. The lower the U-factor, the greater a window's resistance to heat flow and the better its insulating value.
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This note was uploaded on 01/13/2010 for the course ARCH 140 taught by Professor Benton during the Spring '08 term at University of California, Berkeley.

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17_Shading Require - Solar Radiation Window Properties Shading Analysis Arch 140 Lecture#17 Tuesday What happens to solar radiation intercepted by

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