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How can I design automatic slats that will minimize Heating + Cooling Loads + Electric Lighting in a classroom?

asked 2017-07-23 10:58:00 -0600

sirYESsir gravatar image

updated 2017-07-24 03:50:42 -0600

I would like to know the influence that automatic slats would have on the total electric consumption of a school, specially on Summer.

For this season, the interesting topic to assess is how closed should the slats be, remembering that if the solar radiation is being a representative load, the slats will close, but the luminosity will also decrease and, reached a certain level, the lights will rather be turned on, representing an extra consumption.

In a nutshell: for certain weather conditions, it would be better to leave the slats open altogether and meet the cooling loads alone, with no need to turn the lights on.

Is there a way to address this problem with Energyplus?

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(FYI, we have a convention on UnmetHours to not include greetings such as Thank you, etc)

Julien Marrec gravatar imageJulien Marrec ( 2017-07-24 03:51:48 -0600 )edit

Is your question how to model automatic slats that open/close continuously (or stepped) based on luminosity?

Or how to model "magic" slats that would open/close at each time step as needed to minimize energy consumption/cost?

Julien Marrec gravatar imageJulien Marrec ( 2017-07-24 03:58:01 -0600 )edit

Also, define "closed".

A blind comprised of slats has typically two main parameters: the slat angle, and how much of the blind covers the window (typically you can retract the blind from the bottom up, as well as vary the slat angle). Out of the box (no EMS) in E+, you can vary the slat angle very easily, varying the blind coverage is harder.

Julien Marrec gravatar imageJulien Marrec ( 2017-07-24 04:09:04 -0600 )edit

@Julien Marrec: I don't really know which would be better to model. My only goal is to reduce the costs and meet the glare comfort at the same time. Regarding the 'closed' concept, I guess the best would be, for starters, to fully retract them at night - so that heat would escape through the windows more easily during that period; and keep them closed with a specific angle during the day. This would be the Summer scenario. The opposite would be applied for Winter.

sirYESsir gravatar imagesirYESsir ( 2017-08-01 10:39:54 -0600 )edit

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answered 2017-07-24 04:16:28 -0600

The short story here without using any EMS is to use:

If BlockBeamSolar, the slat angle is set each timestep to just block beam solar radiation. If there is no beam solar on the window the slat angle is set to the value input for the WindowMaterial:Blind that is contained in the construction specified by Name of Construction with Shading or is specified by Material Name of Shading Device. The BlockBeamSolar option prevents beam solar from entering the window and causing possible unwanted glare if the beam falls on work surfaces while at the same time allowing near-optimal indirect radiation for daylighting

This is going to allow you to vary:

  • The slat angle
  • Whether the blind is deployed or not. That's binary, not varying. Either fully deployed, either fully retracted.
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@Julien Marrec: If I define all of those objects that you just mentioned, are the lights going to be adjusted according to the luminosity and the schedule of the room? If so, what was the setpoint luminosity?

sirYESsir gravatar imagesirYESsir ( 2017-08-01 10:33:43 -0600 )edit

Whether you have blinds or not, if you want to adjust the lighting power based on a setpoint (lux), you need to add daylighting controls (see here and there are have been questions asked about lighting controls on unmet hours, do a search)

Julien Marrec gravatar imageJulien Marrec ( 2017-08-02 03:42:38 -0600 )edit

How to fully retract the blinds when slat control = BlockBeamSolar and no solar beam is reaching the window?

sirYESsir gravatar imagesirYESsir ( 2017-08-31 09:09:55 -0600 )edit

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Asked: 2017-07-23 10:58:00 -0600

Seen: 102 times

Last updated: Jul 24 '17