Re: [EnergyPlus_Support] Room Air Modeling

Thanks for your input. I checked the RDD as well as Input/Output ref. and it seems that the only extra output you get from the 'nondimensional height' roomair model is the thermostat temperature, and this 'room air zone thermostat temperature' is purely cosmetic. When I change the input thermostat offset from 0.4 (a measured value) to 100 (a made-up-nonsense value), nothing changes in the simulation. But in the paper that the EnergyPlus documentation references (Griffith et al), they provide a way to change the air heat balance equation to reflect thermostat offset. And Griffith wrote the source code for many of the roomair models. So it seems the thermostat offset is not implemented in nondimensional height roomair models, which is not what the documentation says.

Am I wrong? Any advice on where to find the heat balance equations in the source code so I can verify?

Thank you!

Ryan Kennett

On Monday, February 8, 2016 4:27 AM, "Jean Marais jeannieboef@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

There are other outputs for these objects which show the theoretical temperature at different heights as well as at the thermostat height. Look for them in your rdd file (I assume you have specified it to be written out as an output). That way you can control if you are getting the stratification that you hope to get.

EnergyPlus should be controlling on the thermostat temperature. That's the main function of these kind of objects.

On 3 Feb 2016 7:22 pm, "ryanwalterkennett@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:

Hi,

I'm modeling a tall facility (25 ft ceiling) using RoomAir:TemperaturePattern:NondimensionalHeight objects to simulate vertical stratification. These objects allow the thermostat temperature to float with the zone's average air temperature on a schedule (I have 24 temperature profiles defined over 1 year on a schedule).

Based on plotting Output:Variable:ZoneAirTemperature and Output:Variable:ZoneThermostatAirTemperature, it is clear that the HVAC system is controlling the average air temperature when it should be controlling the thermostat air temperature (see attached pictures).

Is anybody familiar enough with room air modeling to understand this discrepancy? Perhaps the modeling is correct, and the output variables are simply not up to date with the room air models.

Note: in the images, the thermostat air temperature varies so much because of a retrofit I'm studying. Why isn't the thermostat controlled at setpoint, 22.2 C, and the space temperature varied?

Best,
Ryan Kennett
University of Maryland

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Posted by: Ryan Kennett <ryanwalterkennett@xxxxxxxxx>

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