Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
Jim, I realize your question is now fairly old, but I was just looking at this myself, and found your post, so I thought I'd share my thoughts. I am also looking at the three output variables Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate, Zone Predicted Sensible Load to Cooling Heat Transfer Rate, and Zone Predicted Sensible Load to Setpoint Heat Transfer Rate. I reported these at the "Detailed" level, which might be helpful for clearly seeing what is going on. In my model I have a heating setpoint (23C) and a cooling setpoint (24C) with a 1C deadband between the two. I also reported the Zone Air Temperature. When I compare the zone air temp to the three predicted load variables it seems to make sense in this way:
When the zone temp is in the deadband: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate is zero. (The Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate and Zone Predicted Sensible Load to Cooling Heat Transfer Rate have non-zero values reflecting what it would take to get from the deadband zone temp to the respective setpoint temps.)
When the zone temp is above the cooling setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Cooling Heat Transfer Rate. (Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate also has a non-zero value reflecting what it would take to drop the zone temp all the way down to the heating setpoint.)
When the zone temp is below the heating setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate. (Zone Predicted Sensible Load to Cooling Heat Transfer Rate also has a value reflecting what it would take to heat the zone all the way up to the cooling setpoint.)
| | 2 | No.2 Revision |
Jim, I realize your question is now fairly old, but I was just looking at this myself, and found your post, so I thought I'd share my thoughts. I am also looking at the three output variables Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate, Zone Predicted Sensible Load to Cooling Heat Transfer Rate, and Zone Predicted Sensible Load to Setpoint Heat Transfer Rate. I reported these at the "Detailed" level, which might be helpful for clearly seeing what is going on. In my model I have a heating setpoint (23C) and a cooling setpoint (24C) with a 1C deadband between the two. I also reported the Zone Air Temperature. When I compare the zone air temp to the three predicted load variables it seems to make sense in this way:
When the zone temp is in the deadband: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate is zero. (The Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate and Zone Predicted Sensible Load to Cooling Heat Transfer Rate have non-zero values reflecting what it would take to get from the deadband zone temp to the respective setpoint temps.)
When the zone temp is above the cooling setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Cooling Heat Transfer Rate. (Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate also has a non-zero value reflecting what it would take to drop the zone temp all the way down to the heating setpoint.)
When the zone temp is below the heating setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate. (Zone Predicted Sensible Load to Cooling Heat Transfer Rate also has a value reflecting what it would take to heat the zone all the way up to the cooling setpoint.)
It is also important to note that these values don't reflect the impact of air delivered to the zone, as explained in the response to another question I asked. So, for example, when meeting these loads in simulation, if your system/terminal minimum flow settings and supply air temp limits result in overcooling - that can create an additional load and the additional heating required to counteract it would not be included in these reported values.
| | 3 | No.3 Revision |
Jim, I realize your question is now fairly old, but I was just looking at this myself, and found your post, so I thought I'd share my thoughts. I am also looking at the three output variables Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate, Zone Predicted Sensible Load to Cooling Heat Transfer Rate, and Zone Predicted Sensible Load to Setpoint Heat Transfer Rate. I reported these at the "Detailed" level, which might be helpful for clearly seeing what is going on. In my model I have a heating setpoint (23C) and a cooling setpoint (24C) with a 1C deadband between the two. I also reported the Zone Air Temperature. When I compare the zone air temp to the three predicted load variables it seems to make sense in this way:
When the zone temp is in the deadband: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate is zero. (The Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate and Zone Predicted Sensible Load to Cooling Heat Transfer Rate have non-zero values reflecting what it would take to get from the deadband zone temp to the respective setpoint temps.)
When the zone temp is above the cooling setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Cooling Heat Transfer Rate. (Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate also has a non-zero value reflecting what it would take to drop the zone temp all the way down to the heating setpoint.)
When the zone temp is below the heating setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate. (Zone Predicted Sensible Load to Cooling Heat Transfer Rate also has a value reflecting what it would take to heat the zone all the way up to the cooling setpoint.)
It sounds like there were some odd control issues in the model you were looking at, but in any case comparing the predicted load variables with the zone air temperature should be helpful.
It is also important to note that these values don't reflect the impact of air delivered to the zone, as explained in the response to another question I asked. So, for example, when meeting these loads in simulation, if your system/terminal minimum flow settings and supply air temp limits result in overcooling - that can create an additional load and the additional heating required to counteract it would not be included in these reported values.
| | 4 | No.4 Revision |
Jim, I realize your question is now fairly old, but I was just looking at this myself, and found your post, so I thought I'd share my thoughts. I am also looking at the three output variables Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate, Zone Predicted Sensible Load to Cooling Heat Transfer Rate, and Zone Predicted Sensible Load to Setpoint Heat Transfer Rate. I reported these at the "Detailed" level, which might be helpful for clearly seeing what is going on. In my model I have a heating setpoint (23C) and a cooling setpoint (24C) with a 1C deadband between the two. I also reported the Zone Air Temperature. When I compare the zone air temp to the three predicted load variables it seems to make sense in this way:
When the zone temp is in the deadband: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate is zero. (The Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate and Zone Predicted Sensible Load to Cooling Heat Transfer Rate have non-zero values reflecting what it would take to get from the deadband zone temp to the respective setpoint temps.)
When the zone temp is above the cooling setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Cooling Heat Transfer Rate. (Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate also has a non-zero value reflecting what it would take to drop the zone temp all the way down to the heating setpoint.)
When the zone temp is below the heating setpoint: the Zone Predicted Sensible Load to Setpoint Heat Transfer Rate has the same value as the Zone Predicted Sensible Load to Heating Setpoint Heat Transfer Rate. (Zone Predicted Sensible Load to Cooling Heat Transfer Rate also has a value reflecting what it would take to heat the zone all the way up to the cooling setpoint.)
It sounds like there were some odd control issues in the model you were looking at, but in any case comparing the predicted load variables with the zone air temperature should be helpful.
It is also important to note that these values don't reflect the impact of air delivered to the zone, as explained in the response to another question I asked. So, for example, when meeting these loads in simulation, if your system/terminal minimum flow settings and supply air temp limits result in overcooling - that can create an additional load and the additional heating required to counteract it would not be included in these reported values.
