Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Dear Parker,
Thank you for your analysis.
The outdoor air in this model really is empty and the thermal load was a little low because of that, but I have done several other models and I always think the load is too low. I´ve compared the same model simulations in Trace 700 and EnergyPlus and the results in Trace are always higher, in some cases up to 3 times.
When analyzing the sources of the loads in the results of both softwares, I noticed that the loads, due to solar radiation, are the most divergent. In some cases, the fenestration solar load is up to 10 times higher in Trace. I find that very strange. My opinion is that the Trace results seem more suitable, because in some cases the glass area is very large and the loads of EnergyPlus do not seem to follow the increase in glasses. The loads due to ventilation and infiltration are also very different.
I don´t think the input data is wrong. I think it could be some software configuration on how to account for the load due to radiation. Perhaps the following fields are not with the defaults well configured in OpenStudio:
In Timesteps Averaging Window: blanck field
Number of Timesteps Per Hour: 6
Maximum Number of Days Warmup: 25
Minimum Number of Days Warmup: 6
Loads Convergence Tolerance Value: 0:04
Temperature Tolerance Value Convergence: 00:04
Solar Distribution: FullInteriorAndExterior
Tolerance For Time Cooling Setpoint Not Met: 0.2
Maximum HVAC Iterations: 20
Minimum Plant Iterations: 2
Maximum Plant Iteration: 8
Minimum System TimeStep: blank field
I will develop a simplified model in Trace 700 and EnegyPlus - OpenStudio and publish the files and results in a new topic for further discussion.
I believe it would be of great importance to have an opinion about possible differences between both softwares, since they are two well-known tools. However, I think the results should be similar, which I have not seen in my experiments.
| | 2 | No.2 Revision |
Dear Parker,
Thank you for your analysis.
The outdoor air in this model really is empty and the thermal load was a little low because of that, but I have done several other models and I always think the load is too low. I´ve compared the same model simulations in Trace 700 and EnergyPlus and the results in Trace are always higher, in some cases up to 3 times.
When analyzing the sources of the loads in the results of both softwares, I noticed that the loads, due to solar radiation, are the most divergent. In some cases, the fenestration solar load is up to 10 times higher in Trace. I find that very strange. My opinion is that the Trace results seem more suitable, because in some cases the glass area is very large and the loads of EnergyPlus do not seem to follow the increase in glasses. The loads due to ventilation and infiltration are also very different.
I don´t think the input data is wrong. I think it could be some software configuration on how to account for the load due to radiation. Perhaps the following fields are not with the defaults well configured in OpenStudio:
In Timesteps Averaging Window: blanck field
field
Number of Timesteps Per Hour: 6
6
Maximum Number of Days Warmup: 25
25
Minimum Number of Days Warmup: 6
6
Loads Convergence Tolerance Value: 0:04
0:04
Temperature Tolerance Value Convergence: 00:04
00:04
Solar Distribution: FullInteriorAndExterior
FullInteriorAndExterior
Tolerance For Time Cooling Setpoint Not Met: 0.2
0.2
Maximum HVAC Iterations: 20
20
Minimum Plant Iterations: 2
2
Maximum Plant Iteration: 8
8
Minimum System TimeStep: blank field
I will develop a simplified model in Trace 700 and EnegyPlus - OpenStudio and publish the files and results in a new topic for further discussion.
I believe it would be of great importance to have an opinion about possible differences between both softwares, since they are two well-known tools. However, I think the results should be similar, which I have not seen in my experiments.
