Tim Johnson's profile - activity

After spending some time with a grocery store model, it seems there is an issue with how the Refrigeration:Condenser:AirCooled object is controlling the condenser fans. This object has very few inputs to determine power and capacity, just the rated fan power and a linear curve for condenser capacity. If it is cold outside, everything operates as it should, the fan speed drops and the condensing temperature is set constant at the minimum specified in the input. When the outdoor air temperature rises above that minimum condensing temperature, the program forces the fans to run at 100% all the time. Instead these fans should operate to maintain a dT between the outdoor air temperature and condensing temperature.

For example, if it is 90F outside, the condensing temperature should be 100F if we are maintaining a 10F dT. instead, I am seeing the dT at 3-5F because the fans are running flat out, using way more energy than they should. This isn't a big deal for colder climates, but when I move this model to Miami, the condenser fans run at essentially 100% all year.

Looking at the [Engineering Reference], the condensing temperature is determined by a variable called Hrej divided by HrejRated rather than a constant dT when the outside air temp is warm. The system then thinks the condenser fans need to run at 100% to maintain this low condensing temperature.

So far, I have experimented with the linear curve coefficient, min/max values, speed control type, and minimum fan speed. Please let me know if I am missing something.

Here is the % capacity by outside air temperature:

and the dT between outside air temp and condensing temperature:

Great stuff. Thanks Eric!

Eric, thanks for the detailed analysis, this is really great stuff. We should be able to figure out the EMS to change th

Refrigeration Air Cooled Condenser Curves - EnergyPlus After spending some time with a grocery store model, it seems the

I am looking to show the impact of thermal mass on building performance and looking for an hourly report that shows the time delay and peak load shaving that is typical of a thermally massive wall. EnergyPlus outputs include conduction, convection, radiation, and storage variables, but I am struggling to interpret the results and their relation to the zone.

Intuitively, I figured the convection and radiation components of the inside surface would add up to the heat transfer to the space, but the results don't match the trends I was expecting. This sum shows the shift in peak load, but a mass wall of similar U-value has much higher peaks than a frame wall.

The table outputs show a peak load for each zone, but I am looking for hourly trends and would like to evaluate walls by exposure. I am not looking for the total zone wall heat transfer.

Can someone shed some light on this for me?

Thanks, Tim

As a temporary fix, I set up the availability managers how I wanted them in OpenStudio, then ran the OpenStudio simulati

Thanks for the quick response. I just installed 2.9.0 and ran it again. I get the same applicability schedule error.

Did either of you figure out this issue? I am having the same problem, but can't seem to replicate it on a simplified mo

Did either of you figure out this issue? I am having the same problem, but can't seem to replicate it on a simplified mo

After upgrading to OpenStudio 2.1.0, followed by 2.1.1, I am no longer able to open the "Results Summary" tab in the OS interface. I am able to run models successfully and view the results in the model folder, but the program locks up after clicking on the "Results Summary" tab. I have tried this with and without the "OpenStudio Results" measure and it does not seem to make a difference. I can access all the files I need, but it is inconvenient to have to dig them up in the folder structure. Any ideas?

I am having further issues beyond what was discussed here and here with the OpenStudio 2.5.1 updates. The error says it is unable to find the eplusout.sql file in my local temp folder. I don't understand how this folder fits into the measure, but I do know the I have an eplusout.sql file in my run folder that seems to work fine though it is nearly 200 MB. Here is the error from the baseline measure log:

ERROR Results for the run couldn't be found here: C:/Users/timj/AppData/Local/Temp/OpenStudioApp.MS1964/ApplyMeasureNow/run/000_6c1da0f7-8c62-40b0-a0e2-d327568f89c5/output/SR1/run/eplusout.sql.

This is a fairly large model at 320k sf and 120 or so zones. The OSM runs, but takes over 3 hours with no major red flags that I can see. This particular ECM is a 2012 IECC code compliance model that needs to be adapted to 2010 Appendix G. I have my .osm located here for reference. It doesn't seem to matter if I apply the 2010 or 2013 measure.

Any help on this would be appreciated as I have struggled to get the baseline measure to run on these larger OpenStudio models.

Eric, thanks for the help, that did the trick. When I applied other HVAC measures, they must have left some pieces. I'll

OS 2.5.1 Baseline Measure I am having further issues beyond what was discussed here and here with the OpenStudio 2.5.1

OS 2.5.1 Baseline Measure I am having further issues beyond what was discussed here and here with the OpenStudio 2.5.1

@aparker, if you are interested in investigating my model, I would love to hear what you find. You can find the model h

Interesting. I guess mine is a different issue. I'll post the solution if I figure it out.

I found it at C:\Users\MyUserName\BCL

Interesting. Are there other characters that might cause this? The only special characters I have are colons and dashes.

Thanks @aparker, I will check it out when the BCL is back online.

I am getting a similar error. Any updates on this?

The latest OpenStudio 2.5.0 release does not seem to be compatible with the "Create DOE Prototype Building" measure. It doesn't seem to matter which code or building type I pick. Is there a simple fix to the script that would take care of this?

This seems to have done the trick for the prototype script, but not the baseline script. Do you have an ETA on the Basel

Thanks for dealing with this, @David Goldwasser. This script and the baseline script are awesome scripts that really hel

OpenStudio's refrigeration systems are geared towards commercial refrigeration, so the would likely be way oversized for