The use of venetian blinds to control solar gain through windows is common in both residential and commercial buildings, and their potential for reduction in peak cooling load and energy consumption is recognized to be large. As such, there is a strong need for models that allow a venetian blind to be included in glazing system analysis. A simplified method of calculating the “effective” solar optical properties of a venetian blind is presented. The solar optical properties of the entire blind are determined based on slat geometry and the optical properties of the slat material, and on the direction and nature (beam or diffuse) of incident radiation. The slat material optical properties are assumed to be independent of the angle of incidence, and are assumed to transmit and reflect beam radiation diffusely. As a first approximation, the slats are assumed to be flat with negligible thickness. A correction is then developed and applied that accounts for the curvature of the slat. The results of the flat and curved slat models are compared with experimental data for commercially available venetian blinds. Both models demonstrate excellent agreement with experiments, except when the profile and slat angles are aligned. In that case, the flat slat model predicts blind transmissions that are too large. The models developed in this study provide useful input to multilayer glazing/shading models used for rating or for building energy simulation.

1.
Breitenbach
,
J.
,
Lart
,
S.
,
Langle
,
I.
, and
Rosenfeld
,
J. L. J.
, 2001, “
Optical and Thermal Performance of Glazing With Integral Venetian Blinds
,”
Energy Build.
0378-7788,
33
, pp.
433
442
.
2.
Jiang
,
T.
, 2005, “
Transmittance Measurements of Louvered Blinds Using a Broad Area Illumination Integrating Sphere
,” MS thesis, University of Waterloo, Waterloo, ON.
3.
Parmelee
,
G. V.
, and
Aubele
,
W. W.
, 1952, “
The Shading of Sunlit Glass—An Analysis of the Effect of Uniformly Spaced Flat Opaque Slats
,”
ASHVE Transactions
,
58
, pp.
377
398
.
4.
Pfrommer
,
P.
,
Lomas
,
K. J.
, and
Kupke
,
Chr.
, 1996, “
Solar Radiation Transport through Slat-Type Blinds: A New Model and Its Application for Thermal Simulation of Buildings
,”
Sol. Energy
0038-092X,
57
(
2
), pp.
77
91
.
5.
Rosenfeld
,
J. L. J
,
Platzer
,
W. J.
,
Van Dijk
,
H.
, and
Maccari
A.
, 2000, “
Modelling the Optical and Thermal Properties of Complex Glazing: Overview of Recent Developments
,”
Sol. Energy
0038-092X,
69
, pp.
1
13
.
6.
Yahoda
,
D. S.
, and
Wright
,
J. L.
, 2005, “
Methods for Calculating the Effective Solar-Optical Properties of a Venetian Blind Layer
,”
ASHRAE Trans.
,
111
(
1
), pp.
572
586
.
7.
Klems
,
J. H.
, 1994, “
A New Method for Predicting the Solar Heat Gain of Complex Fenestration System—1. Overview and Derivation of the Matrix Layer Calculation
,”
ASHRAE Trans.
,
100
(
1
), pp.
1065
1072
.
8.
Klems
,
J. H.
, 1994, “
A New Method for Predicting the Solar Heat Gain of Complex Fenestration System—2. Detailed Description of the Matrix Layer Calculation
,”
ASHRAE Trans.
,
100
(
1
), pp.
1073
1086
.
9.
Wright
,
J. L.
, and
Kotey
,
N. A.
, 2006, “
Solar Absorption by Each Element in a Glazing/Shading Layer Array
,”
ASHRAE Trans.
,
112
(
2
), pp.
3
12
. 0038-092X
10.
Edwards
,
D. K.
, 1977, “
Solar Absorption by Each Element in an Absorber-Coverglass Array
,”
Sol. Energy
0038-092X,
19
, pp.
401
402
.
11.
Platzer
,
W. J.
, 2005, “
Performance Assessment for Solar Shadings—State of the Art
,” http://www.glassfiles.com/library/2/article978.htmhttp://www.glassfiles.com/library/2/article978.htm.
12.
Collins
,
M.
, and
Jiang
,
T. R.
, 2008, “
Validation of Solar/Optical Models for Louvered Shades Using a Broad Area Illumination Integrating Sphere
,”
ASHRAE Trans.
,
114
(
1
), pp.
483
490
.
13.
Kotey
,
N. A.
, and
Wright
,
J. L.
, 2006, “
Simplified Solar Optical Calculations for Windows With Venetian Blinds
,”
Proceedings of the 31st Conference of the Solar Energy Society of Canada Inc. (SESCI)
.
14.
Yahoda
,
D. S.
, and
Wright
,
J. L.
, 2005, “
Methods for Calculating the Effective Longwave Radiative Properties of a Venetian Blind Layer
,”
ASHRAE Trans.
,
110
(
1
), pp.
455
462
.
15.
Milburn
,
D. I.
, and
Hollands
,
K. G. T.
, 1994, “
Solar Transmittance Measurements Using an Integrating Sphere With Broad Area Irradiation
,”
Sol. Energy
0038-092X,
52
(
6
), pp.
497
507
.
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