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OpenStudio 1.6 overwriting setpoint schedules

asked 2015-03-13 15:04:16 -0600

updated 2015-07-10 09:08:36 -0600

Hi there,

I'm witnessing some strange behavior in OpenStudio 1.6 with a simple 3-zone residential model for Amsterdam. I'm trying to create two heating setpoint schedules: one for constant 15C and one that has 21C during the day. I'm only applying the 21C setpoint schedule to one zone, the other two are constant 15C. I'm also using Ideal Air Loads and have not created an HVAC system.

First, when I am in the Thermal Zones tab to set the Heating Thermostat Schedule, after making a change OpenStudio isn't asking me to save the file before running a simulation. It has always done that for me in the past.

Second, after running a simulation, the Heating Thermostat Schedule assignment is overwritten for all three zones to be the same. The schedule used is whatever the last schedule I assigned.

Screenshot before running a simulation, where two zones are always 15C and one zone has 21C setback" image description

Screenshot after running a simulation, where all three zones have 21C setback image description

Any thoughts or insight about these issues?

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Just an aside, I did download and install 1.6 today, so there is a chance it is installation-related.

Aaron Boranian's avatar Aaron Boranian  ( 2015-03-13 15:05:27 -0600 )edit

I also just noticed that even if I add Zone Air Temperature as an output variable to be reported in the eplusout.csv file, the file isn't created by OpenStudio in the 5-EnergyPlus-0 directory. I have to simulate the generated out.idf file in EnergyPlus to generate the eplusout.csv file.

Aaron Boranian's avatar Aaron Boranian  ( 2015-03-13 15:12:25 -0600 )edit

2 Answers

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answered 2015-03-13 15:38:49 -0600

When you are in the Thermal Zone tab in OS and you edit the schedules, you are deleting or changing the schedule on a thermostat, not editing or changing the thermostat itself. To do what you are talking about you need to make a new thermostat in SketchUp, and then apply it to the zones you want in SketchUp as well.

First you need to make heating and cooling schedules that you want in OS. image description

Next in the inspector tool in OS add a thermostat and assign the schedules you made. image description

Finally assign this thermostat to the desired zones in Sketchup's inspector tool.image description

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@TaylorRoberts, nice answer. I'm going to detail the issue in another answer and explain the behavior in more detail. Also, looks like your second screenshot was mistakenly a duplicate of the first.

David Goldwasser's avatar David Goldwasser  ( 2015-03-13 23:43:33 -0600 )edit

answered 2015-03-14 00:17:42 -0600

The OpenStudio SketchUp Plugin and the stand alone OpenStudio application have always dealt with thermostats in a different way, which is confusing, and is something that we do need to address. In the underlying API a Thermostat is a shared resource that can be assigned to more than one thermal zone. It is accessible in the plugin via the inspector and also the space attributes dialog. The thermostat object is really a holder for a two schedules; a cooling and heating setpoint schedule.

In the stand alone OpenStudio application the user is shielded from seeing the thermostat object. Only the two setpoint schedules are exposed. Under the hood the approach is more like the thermostat is a child of a thermal zone and when starting from a clean model the thermostats are created when you drop schedules onto the setupoint dropzones.

Generally either of these approaches are fine, but the issues occur when you start in the SketchUp plugin and assign the thermostat to more than one thermal zone. Then you move to the OpenStudio application and try to change the thermostats for just one of the thermal zones. If you change one, they all change, and you can't detach them from each other.

In just doing some testing now I have confirmed a few things.

  1. At first glance when you do add a thermostat to one zone, it looks like it only affects that zone. But if you leave the zone tab and go back, or if you inspect the file you will see it did change all of the zones using that shared thermostat.
  2. With the removal of the on/off button for thermostats, which was generally a good thing, an un-expected byproduct is that you can no longer detach the shared thermostat from within the OpenStudio application. When you remove both the heating and cooling set points, the thermostat is still there, vs. mimicking what the off button would have done in the past.

There is an open issue for this, I'll update it with this information, which reflects change that came in with grid view thermal zone view. Thanks for providing the detail about what was happening. For now you will have to jump into the Plugin like @TaylorRoberts suggested.

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Asked: 2015-03-13 15:04:16 -0600

Seen: 928 times

Last updated: Mar 14 '15