Heat Gains into a Building Solar Gains Shading

Attendance A.

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What improvement did George Ravenscroft (1618 – 1681) develop to make glass windows economically feasible?

Made it square Added color to make it more attractive Added lead oxide Learned how to bevel the glass Made it thinner

What You Need to Know How solar radiation effects cooling loads

What You Need to be Able To Do Be able to calculate solar loads Develop strategies to limit/postpone/utilize solar loads

Terms Fenestration Solar Heat Gain Factor (SHGF) Shading Coefficient (SC)

Sunlit Glass sun rays Fenestration “Any opening in the external envelope of a building that allows light to pass.” reflected energy

conduction solar gain (radiation)

transmitted energy glass window

Q S = solar gain + conduction

Glass - Conduction •Calculated the same way as heating for conduction

Q conduction = U

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Calculating the Solar Gain where: Q = SHGF x A x SC SHGF = Solar Heat Gain Factor A = Area SC = Shading Coefficient

Solar Heat Gain Factor (SHGF), Table 2-15A Do you see the three variables?

Shading Coefficients Table 2-16

Shading Strategies Fins Overhangs

Shading Strategies Adjacent Buildings

Shading Strategies A completely shaded window is similar to a North facing window

Accounting for Shade In the Northern hemisphere, use the North Column

Effect of Glass on a South Wall Glass – Conduction Q C Q C Q C = U x A x (T 2 – T 1 ) = .47 x (24 x 4) x 17 = 767 Btu/Hr Wall – Conduction Q C Q C = U x A x TETD = .26 x 377 x 19 Q C = 1,875 Btu/Hr Glass – Solar Q S Q S = SC x A x SHGF = .90 x (24 x 4) x 29 Q S = 2,505 Btu/Hr Q T = 2278 Btu/Hr

LEED EA Credit 1 Credit 1 – Optimize energy performance (1 to 10 points)    Building orientation Harvest free energy Sustainable strategies

Cooling Peak Load – Sum of All Cooling Loads at Peak Conditions Latent Roof = Wall S Wall N = = Wall E = Glass S Glass N = = People (30) = Ventilation (372) = Infiltration = Sensible 14,253 Btu/Hr 1,875 Btu/Hr 593 Btu/Hr 2,162 Btu/Hr 3,272 Btu/Hr 797 Btu/Hr 7,350 Btu/Hr 8,184 Btu/Hr 0 TOTAL 38,486 Btu/Hr 4,650 Btu/Hr 7,083 Btu/Hr 0 11,733 Btu/Hr