Issues with Switchable Glazing Solar Gain Setpoint

asked 2016-02-16 20:29:05 -0500

StefanG

181 ●1 ●3

updated 2017-06-04 10:28:46 -0500

__AmirRoth__

4436 ●5 ●17 http://bleedinggreenna...

I'm trying to implement electrochromic glass in an OpenStudio 1.10 model as switchable glazing under shading controls, but I noticed that the shading controls had no effect on energy performance. After digging into the IDF, I found that the setpoint for solar gain on the windows to activate the switchable glazing was 5,000 W/m2. I have not had this problem previously in OpenStudio 1.9, so it seems that this is a new issue with OpenStudio 1.10. Has anyone else encountered this?

Find my OSM here: https://www.dropbox.com/s/s4wxmjvocli...

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See my comment on Dan's answer here. This post is also relevant.

Julien Marrec ( 2016-02-17 00:57:59 -0500 )edit

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answered 2016-02-17 03:53:04 -0500

nico

51 ●5

I noticed the same issue with a screen. A blank field in OpenStudio results in 5000 W/m2 value in IDF.

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answered 2016-02-17 01:04:51 -0500

Julien Marrec

29042 ●85 ●74 http://www.effibem.com/

Previously you couldn't set the shading setpoint in the GUI nor in the API. It seems that you can at least set it in the API, see the SDK Documentation, there is a setSetpoint method that accepts a double.

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answered 2016-02-17 09:35:57 -0500

rpg777
6960 ●6 ●15 http://openstudio.net/

You can absolutely change the setpoint to whatever you wish. The default is 5,000, but the units ASSumption is also lux, not watts. This was to support the Radiance controls and from this viewpoint is looking like an incomplete solution. =/

If you're only using EnergyPlus, you can simply adjust the setpoint to whatever you want and you'll be all good. If using Radiance for the daylighting, the simulations will either have a ridiculously low setpoint for the daylighting or a overly high one for the thermal simulation. We will file an issue for this, to make the behavior and the defaults more consistent and reasonable.

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Issues with Switchable Glazing Solar Gain Setpoint