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Issues with Switchable Glazing Solar Gain Setpoint

asked 2016-02-16 20:29:05 -0600

StefanG gravatar image

updated 2017-06-04 10:28:46 -0600

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:

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

Julien Marrec gravatar image Julien Marrec  ( 2016-02-17 00:57:59 -0600 )edit

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answered 2016-02-17 09:35:57 -0600

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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answered 2016-02-17 01:04:51 -0600

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 03:53:04 -0600

nico gravatar image

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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Asked: 2016-02-16 20:29:05 -0600

Seen: 295 times

Last updated: Feb 17 '16