HEAT TRANSFER TO A SUNROOM

1
HEAT TRANSFER TO A SUNROOM

• the affect of window type on heat transfer

2
The Situation

• Clear Day
• Mid June
• Provo, UT
• The Pates have recently added a sunroom to the
  exterior of their home. In the summer the
  temperature rises in that room a considerable
  amount. Should they have installed double pane
  windows instead? Should they invest in windows
  with reflective coating? How much of a
  difference would these windows make?

3
What We Know

• Incident Solar Radiation
• East Wall 5015 W/m2
• South Wall 2997 W/m2
• West Wall 5015 W/m2
• Temperature Data
• Tsur, interior 20 C
• Tsur, exterior 35 C
• Physical Properties
• Glass (T300K)
• 1.4 W/mK
• Air
• K.0263 W/mK (T300K)

• Areas of Windows
• East Wall
• 8.09 m2
• South Wall
• 6.77 m2 (x 2)
• 2.60 m2 (x2)
• West Wall
• 8.09 m2
• Volume of the Room
• 60 m3

4
What We Assume

• Radiation Properties of Glass
• Transmissivity .95
• Absorbtivity 0
• Reflectivity .05
• Emissivity .9
• Neglect radiation out of the room (only consider
  incident radiation)

• No heat transfer through the walls
• Tsur stays constant
• Window areas are all square (see diagram)

5
Single Pane Glass

• ho,i 6 W/m2
• qconvcond 728 W
• qrad 1606 W
• qtotal 2324

Ho, To
Hi , Ti
6
Double Pane Glass

• RaL91.37 ?T
• RaLmax 1307
• 1307 lt 1708
• Convection between planes is negligible.
• Transmissivity .9
• Reflectivity .1
• h 6 W/m2
• qconvcond 168 W
• qrad 1522 W
• qtotal 1690 W

Ho, To
Hi , Ti
7
Double Pane Glass with Coating

• Reflective glass
• Reflectivity .28
• Transmissivity .72
• Heat transfer from convection and conduction
  stays the same.
• qconvcond 168 W
• qrad 1217 W
• qtotal 1385 W

Ho, To
Hi , Ti
8
Air Conditioning Cost

• Single Pane 122.07
• Double Pane 148.09
• Coated Double Pane 216.12
• .08/KWhr
• COP 3.4
• Summer Savings 94.05
• Coating 36/Window
• Estimate 216 to upgrade, 2.5 Summers to recover
  the savings

9
Presented By

• Nathan Honka
• Dallin Shaw
• Jenny Pate

10
Appendix A Radiation Data
11
Appendix B Equations

• Inside Convection Coefficient

• Thermal Resistances

12
Appendix B Equations

• qconv,i on inner surface
• qcond through window
• qconv,o qcond qconv,i
• Could not solve that system so we assumed h6W/m2
  to determine qconv,i and qconv,o.

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Appendix C Spreadsheet Solution
SINGLE PANE Area (m2) q (cond conv) q (rad) q (total)
SINGLE PANE 8.09 728.1 1606.2695 2334.3695
SINGLE PANE 6.77 609.3 803.9375 1413.2375
SINGLE PANE 6.77 609.3 803.9375 1413.2375
SINGLE PANE 2.6 234 308.75 542.75
SINGLE PANE 2.6 234 308.75 542.75
SINGLE PANE 8.09 728.1 1606.2695 2334.3695
SINGLE PANE       8580.714
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Appendix C Spreadsheet Solution
DOUBLE PANE Area (m2) q (cond conv) q (rad) q (total)
DOUBLE PANE 8.09 167.8 1521.729 1689.529
DOUBLE PANE 6.77 140.4 761.625 902.025
DOUBLE PANE 6.77 140.4 761.625 902.025
DOUBLE PANE 2.6 53.9 292.5 346.4
DOUBLE PANE 2.6 53.9 292.5 346.4
DOUBLE PANE 8.09 167.8 1521.729 1689.529
DOUBLE PANE       5875.908
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Appendix C Spreadsheet Solution
DOUBLE PANE WITH COATING Area (m2) q (cond conv) q (rad) q (total)
DOUBLE PANE WITH COATING 8.09 167.8 1217.3832 1385.1832
DOUBLE PANE WITH COATING 6.77 140.4 609.3 749.7
DOUBLE PANE WITH COATING 6.77 140.4 609.3 749.7
DOUBLE PANE WITH COATING 2.6 53.9 234 287.9
DOUBLE PANE WITH COATING 2.6 53.9 234 287.9
DOUBLE PANE WITH COATING 8.09 167.8 1217.3832 1385.1832
DOUBLE PANE WITH COATING       4845.5664
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Sources

• Incident Solar Radiation Values
  http//geology.utah.gov/sep/renewable_energy/solar
  /images/data_tables/slcbld.jpg