Post on 04-Jan-2016
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Interzone short wave radiative couplings through windows and large openings : proposal of a
simplified model
H. Boyer T. Berthomieu, F. Garde, A. Bastide, T. Mara, F. Miranville
Université de La Réunion
harry.boyer@univ-reunion.fr
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Plan
• Introduction• Initial short wave model and basic
problem • Matricial approach of the couplings • Simulations versus experiments • Conclusion
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Introduction
• Single zone short wave repartition modeling
• What about multizone cases ?
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The basic problem Given indoor diffuse d0 value (W), how to compute short wave radiation leaving the zone ?
•With hypothesis of no direct couplings
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Basic problem solution
=
=
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Transmitted diffuse radiation
With hypothesis of no direct couplings
Direct incident in the zone Diffuse window transmittance
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Extension to multizone case
• Use of interzone short wave matrix of couplings …
• …very similar to matrical airflow matrix
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An example on indoor coupling matrix
1 3
4
2
0
8
21
Zone 0 1 2 3 4 Zone
0
1
2
3
4
Windows
Bay window
Sliding door
• 8 % on incident solar inputs of zone 4 will
be transfered to zone 2
• 21 % of solar inputs of zone 2 zone 4
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Some properties of this matrix
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4
2
8
21
0 1 2 3 4 Zone
0
1
2
3
4
10
+ + + + = 37 %15 + 0 +0 +0 +21
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Final calculation of net diffuse values
• For zone i, di0 is the incident diffuse radiation and di the net
diffuse radiation resulting of the couplings. di ?
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• If aij = 0, the matrix is Id and
• Sum of the 3 equations traduces short wave conservation
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CODYRUN
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CODYRUN’s block solving strategy
•4 basic blocs
•All heat transfer modes taking into account
•Fully coupled approach
•Numerous software ouputs available
for thermal analysis (heat fluxes, …)
Airflow model
Thermal model
Humidity model
CO2 model
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Outputs of CODYRUN software
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Elements of validation
West façade
East façade
N
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Incoming solar radiation
0
50
100
150
200
250
300
1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229
half hours
W/m
²
Measure -> In
Incoming solar radiation
0
50
100
150
200
250
300
1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193 205 217 229
half hours
W/m
²
Measure -> In
CODYRUN
• Incident radiation correctly modeled (=4%)
• Errors linked to uncertaincies on measurments
• Peak in measure linked to single sensor use
Analysis of solar radiation input
N
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Outgoing solar radiation
0
5
10
15
20
25
1 12 23 34 45 56 67 78 89 100
111
122
133
144
155
166
177
188
199
210
221
232
half hours
W/m
²
Measure -> Out
Outgoing solar radiation
0
5
10
15
20
25
1 12 23 34 45 56 67 78 89 100 111 122 133 144 155 166 177 188 199 210 221 232
half hours
W/m
²
CODYRUN
Measure -> Out
• Outgoing radiation weak values
• Errors mainly linked to the model
Analysis of radiation output in a zone
N
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• Existence of direct coupling between Living room
and Room 2
Short wave exchanges ROOM2 -> LIVING ROOM
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100
150
200
250
300
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46
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111
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half hours
W
meas.
Short wave exchanges ROOM2 -> LIVING ROOM
0
50
100
150
200
250
300
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26
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1
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half hours
W
meas.
Phi SW 4->2 (W)
Analysis of couplings between 2 zones
N
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Conclusion
• The proposed method using a diffuse coupling matrix method
- obtains good results for in/out exchanges
- is acceptable only in case of non direct couplings
• Model improvements can be made easily, but need complete
geometrical description of the building.
• Multi sensor experiments will be used to
validate such an approach