Heat Gains into a Building

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# Heat Gains into a Building - PowerPoint PPT Presentation

Heat Gains into a Building. Solar Gains Shading. Attendance. 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.

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### Heat Gains into a Building

Solar Gains

Attendance
• What improvement did George Ravenscroft (1618 – 1681) develop to make glass windows economically feasible?
• Added color to make it more attractive
• Learned how to bevel the glass
What You Need to Know
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)

sun rays

transmitted

energy

conduction

reflected

energy

glass

window

Sunlit Glass

Fenestration

“Any opening in the external envelope of a building that allows light to pass.”

QS = solar gain + conduction

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

Qconduction = U  A TD

Calculating the Solar Gain

Q = SHGF x A x SC

where:

SHGF = Solar Heat Gain Factor

A = Area

Solar Heat Gain Factor (SHGF), Table 2-15A

Do you see the three variables?

• A completely shaded window is similar to a North facing window
• In the Northern hemisphere, use the North Column
Glass – Conduction

QC = U x A x (T2 – T1)

QC = .47 x (24 x 4) x 17

QC = 767 Btu/Hr

Glass – Solar

QS = SC x A x SHGF

QS = .90 x (24 x 4) x 29

QS = 2,505 Btu/Hr

QT = 2278 Btu/Hr

Wall – Conduction

QC = U x A x TETD

QC = .26 x 377 x 19

QC = 1,875 Btu/Hr

Effect of Glass on a South Wall
LEED EA Credit 1
• Credit 1 – Optimize energy performance (1 to 10 points)
• Building orientation
• Harvest free energy
• Sustainable strategies

SensibleLatent

Roof = 14,253 Btu/Hr

WallS = 1,875 Btu/Hr

WallN = 593 Btu/Hr

WallE = 2,162 Btu/Hr

GlassS = 3,272 Btu/Hr

GlassN = 797 Btu/Hr

People (30) = 7,350 Btu/Hr 4,650 Btu/Hr

Ventilation (372) = 8,184 Btu/Hr 7,083 Btu/Hr

Infiltration = 0 0

TOTAL 38,486 Btu/Hr 11,733 Btu/Hr