# daylighting matrix

Hello experts:

I am learning the tutorial "The Three-Phase Daylight Coefficient Method for
Simulating Complex Fenestration with Radiance". I am very confused with the
daylighting matrix. Daylighting matrix should be a matrix with size of
KlemsDivision* SkyPatches. Is that right D-matrix tells me
the contributions of each sky patch to each Klems division (each angle?)?
If so, different point in the window area should have different D-matrix
because the sky patches' contributions to the same direction in different
positions of window are different, in other words, the D matrix is
different. But in fact, there is only one D matrix for a window. Could
someone explain how daylighting matrix works?

Thank you,

Jia

When you say "the sky patches' contributions to the same direction in
different positions of window are different", are you referring to the
effect of shading elements on the window, making those contributions
different? Because in order to model this accurately, you are correct in
that you need more daylight matrices (i.e. need to subdivide the window).
Andy covers this really well in his (fabulous) tutorial (see the Appendix,

Rob Guglielmetti IESNA, LEED AP
Commercial Buildings Research Group
National Renewable Energy Laboratory
1617 Cole Blvd, MS-5202
Golden, CO 80401-3393
T. 303.275.4319
F. 303.384.7540
E. [email protected]

···

On 11/3/10 4:47 PM, "Jia Hu" <[email protected]> wrote:

Hello experts:

I am learning the tutorial "The Three-Phase Daylight Coefficient Method for
Simulating Complex Fenestration with Radiance". I am very confused with the
daylighting matrix. Daylighting matrix should be a matrix with size of
KlemsDivision* SkyPatches. Is that right D-matrix tells me
the contributions of each sky patch to each Klems division (each angle?)?
If so, different point in the window area should have different D-matrix
because the sky patches' contributions to the same direction in different
positions of window are different, in other words, the D matrix is different.
But in fact, there is only one D matrix for a window. Could someone explain
how daylighting matrix works?

Thank you,

Jia

Hello Rob:

Thank you. Yes and I mean the luminance distribution in the window may not
be uniform in case of shading or obstructions. Now I understand more D

Jia

···

On Wed, Nov 3, 2010 at 7:02 PM, Guglielmetti, Robert < [email protected]> wrote:

When you say "the sky patches' contributions to the same direction in
different positions of window are different", are you referring to the
effect of shading elements on the window, making those contributions
different? Because in order to model this accurately, you are correct in
that you need more daylight matrices (i.e. need to subdivide the window).
Andy covers this really well in his (fabulous) tutorial (see the Appendix,

Rob Guglielmetti IESNA, LEED AP
Commercial Buildings Research Group
National Renewable Energy Laboratory
1617 Cole Blvd, MS-5202
Golden, CO 80401-3393
T. 303.275.4319
F. 303.384.7540
E. [email protected]

On 11/3/10 4:47 PM, "Jia Hu" <[email protected]> wrote:

> Hello experts:
>
> I am learning the tutorial "The Three-Phase Daylight Coefficient
Method for
> Simulating Complex Fenestration with Radiance". I am very confused with
the
> daylighting matrix. Daylighting matrix should be a matrix with size of
> KlemsDivision* SkyPatches. Is that right D-matrix tells me
> the contributions of each sky patch to each Klems division (each
angle?)?
> If so, different point in the window area should have different D-matrix
> because the sky patches' contributions to the same direction in different
> positions of window are different, in other words, the D matrix is
different.
> But in fact, there is only one D matrix for a window. Could someone
explain
> how daylighting matrix works?
>
> Thank you,
>
> Jia

_______________________________________________