Annual simulation with electrochromic glass

Hi,

I would like to achieve annual simulation of an electrochromic glass (tint change) with Radiance to obtain room illumination.

I am interested in the 3 phases method, but the glass xml file defines a constant behavior for each hour of the year.

Is it possible to create a file containing the evolutionary behavior of glass every hour?
Or is there another way to simulate this kind of glass (other than one simulation per hour)?

Thanks in advance,
Best regards,

Julien

Julien,

A while ago I saw THESE SLIDES
<https://www.radiance-online.org/community/workshops/2014-london/presentations/day2/Mardaljevic-Electrochromic.pdf/view>by
John Mardaljevic... maybe they can help you.

On the other hand, the method I would choose for simulating electrochromic
glass would be using Daylight Coefficients. It may take longer (depending
on the number of windows and states you want to simulate), but it will
consider the true specularity of the glass (BSDFs used in the 3-phase
method will not allow that).

What I often do is to perform a DC simulation for every state of the office
(I usually work with simple offices with a small amount of windows), and
then use a script or spreadsheet to select what is the state at each hour.
The calculation of the state of the window at each hour will depend on the
control strategy...

I hope this helps

Germán

···

2016-07-06 7:03 GMT-03:00 Julien Boutillier <[email protected]>:

Hi,

I would like to achieve annual simulation of an electrochromic glass (tint
change) with Radiance to obtain room illumination.

I am interested in the 3 phases method, but the glass xml file defines a
constant behavior for each hour of the year.

Is it possible to create a file containing the evolutionary behavior of
glass every hour?
Or is there another way to simulate this kind of glass (other than one
simulation per hour)?

Thanks in advance,
Best regards,

Julien
_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

Just to clarify a bit (hopefully), what German means is that by simulating the glass *as glass*, and tracing rays through an actual glass material to the sky, you will get better results than if you use a BSDF, in the case of a specular transmitter like clear glazing. The standard Klems resolution for the BSDF (and this is what you have available if you use the standard Radiance tools for annual daylight coefficient simulations) will "smear" the spiky direct solar contributions into a single patch subtending 17 degrees, or worse, take that radiation and spread it among three Klems patches. By doing a separate annual daylight coefficient simulation for each tint state of your EC glazing, you can then mix and match the hourly values. As German said, this is what he does with his tools, and this is also what we do with OpenStudio for EC glazing simulations.

- Rob

···

On 7/6/16, 7:45 AM, "Germán Molina Larrain" <[email protected]<mailto:[email protected]>> wrote:

Julien,

A while ago I saw THESE SLIDES <https://www.radiance-online.org/community/workshops/2014-london/presentations/day2/Mardaljevic-Electrochromic.pdf/view> by John Mardaljevic... maybe they can help you.

On the other hand, the method I would choose for simulating electrochromic glass would be using Daylight Coefficients. It may take longer (depending on the number of windows and states you want to simulate), but it will consider the true specularity of the glass (BSDFs used in the 3-phase method will not allow that).

What I often do is to perform a DC simulation for every state of the office (I usually work with simple offices with a small amount of windows), and then use a script or spreadsheet to select what is the state at each hour. The calculation of the state of the window at each hour will depend on the control strategy...

I hope this helps

Germán

2016-07-06 7:03 GMT-03:00 Julien Boutillier <[email protected]<mailto:[email protected]>>:
Hi,

I would like to achieve annual simulation of an electrochromic glass (tint change) with Radiance to obtain room illumination.

I am interested in the 3 phases method, but the glass xml file defines a constant behavior for each hour of the year.

Is it possible to create a file containing the evolutionary behavior of glass every hour?
Or is there another way to simulate this kind of glass (other than one simulation per hour)?

Thanks in advance,
Best regards,

Julien
_______________________________________________
Radiance-general mailing list
[email protected]<mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general

Hi Julien,

You can simulate an estimate of electrochromic glass performance fairly
easily with SPOT Pro <http://www.daylightinginnovations.com/spot-home>. It
is a work-around and performance estimate but does not have the limitations
(smearing that Rob mentioned) that a daylight cofficient approach might
have with a specular product. You can also control the electrochromic via
an actual exterior photosensor signal or using advanced manual control
algorithms.

In SPOT to simulate electrochromic glazing, you just apply a "multiplier"
glazing as the window treatment. Your base window might have the ~58%
transmittance of a clear state. Then, say, the most tinted state is ~1%,
you can define a 1.7% transmittance glass and apply as the window
treatment. This is not the most accurate way to model in Radiance as it
introduces another uneccesary surface and reflectance interactions but
should work well enough for annual space performance analysis. This only
models the top and bottom tint state, but I think it comes pretty close to
simulating annual performance as I am not sure how often in between states
are even used. As a designer or an occupant, I would want to have the
darkest tint if I was under direct sunlight and the clearest tint
otherwise. They exist, but there are limited hours where there is no
direct sunlight but the clouds/sky are just too bright. SPOT would not
capture these 2nd and 3rd state conditions.

A more accurate generic electrochromic model is in the works and will be
included in an upcoming SPOT release.

Cheers,
Zack

···

On Wed, Jul 6, 2016 at 4:03 AM, Julien Boutillier <[email protected]> wrote:

Hi,

I would like to achieve annual simulation of an electrochromic glass (tint
change) with Radiance to obtain room illumination.

I am interested in the 3 phases method, but the glass xml file defines a
constant behavior for each hour of the year.

Is it possible to create a file containing the evolutionary behavior of
glass every hour?
Or is there another way to simulate this kind of glass (other than one
simulation per hour)?

Thanks in advance,
Best regards,

Julien
_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general

--
Zack Rogers, P.E., LEED AP BD+C
Daylighting Innovations, LLC
808 S. Public Road, Suite 200
Lafayette, CO 80026
(303)946-2310

www.daylightinginnovations.com

Hi,

Thank you for your answers (German, Rob and Zack).

I will check all this information.

Best regards,

Julien

···

Le 6 juil. 2016 à 20:25, Zack Rogers <[email protected]> a écrit :

Hi Julien,

You can simulate an estimate of electrochromic glass performance fairly easily with SPOT Pro <http://www.daylightinginnovations.com/spot-home>. It is a work-around and performance estimate but does not have the limitations (smearing that Rob mentioned) that a daylight cofficient approach might have with a specular product. You can also control the electrochromic via an actual exterior photosensor signal or using advanced manual control algorithms.

In SPOT to simulate electrochromic glazing, you just apply a "multiplier" glazing as the window treatment. Your base window might have the ~58% transmittance of a clear state. Then, say, the most tinted state is ~1%, you can define a 1.7% transmittance glass and apply as the window treatment. This is not the most accurate way to model in Radiance as it introduces another uneccesary surface and reflectance interactions but should work well enough for annual space performance analysis. This only models the top and bottom tint state, but I think it comes pretty close to simulating annual performance as I am not sure how often in between states are even used. As a designer or an occupant, I would want to have the darkest tint if I was under direct sunlight and the clearest tint otherwise. They exist, but there are limited hours where there is no direct sunlight but the clouds/sky are just too bright. SPOT would not capture these 2nd and 3rd state conditions.

A more accurate generic electrochromic model is in the works and will be included in an upcoming SPOT release.

Cheers,
Zack

On Wed, Jul 6, 2016 at 4:03 AM, Julien Boutillier <[email protected] <mailto:[email protected]>> wrote:
Hi,

I would like to achieve annual simulation of an electrochromic glass (tint change) with Radiance to obtain room illumination.

I am interested in the 3 phases method, but the glass xml file defines a constant behavior for each hour of the year.

Is it possible to create a file containing the evolutionary behavior of glass every hour?
Or is there another way to simulate this kind of glass (other than one simulation per hour)?

Thanks in advance,
Best regards,

Julien
_______________________________________________
Radiance-general mailing list
[email protected] <mailto:[email protected]>
http://www.radiance-online.org/mailman/listinfo/radiance-general

--
Zack Rogers, P.E., LEED AP BD+C
Daylighting Innovations, LLC
808 S. Public Road, Suite 200
Lafayette, CO 80026
(303)946-2310

www.daylightinginnovations.com <http://www.daylightinginnovations.com/>
_______________________________________________
Radiance-general mailing list
[email protected]
http://www.radiance-online.org/mailman/listinfo/radiance-general