I do not understand why you are not using the zone thermostat control with some schedules. What is the time lag you are considering? Are you trying to measure the time lag of an AHU.
An AHU for one zone can use the zone thermostat directly without the setpoint managers.
If you have both heating and cooling, let the building temperature float to the OA temperature and start cooling or heating in steps to the value you want for the occupied time. Do the reverse in the evening or at night.
In an AHU, a set point is used for the heat source feeding the coils. The fan controls the air flow rate. The zone thermostat would control the fan or the coil, depends on whether you wanted to use constant fan of on/off fan.
The water flow rate in the coil is changed to adjust the supply capacity to the demand requirements. With a DX coil, the PLR of the compressor is changed to change the supply capacity..
================================
If you are thinking about the start up time for a boiler, you may limit the heat supply and watch the temperature rise per time step, with a boiler availability schedule..
The rise time of the AHU is also visible in the variable report, if the coil has a lower set point temperature or flow rate, so that the air cannot be heated to the final temperature in one time step..
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: andreacostaenergyplus@xxxxxxxxx
Date: Tue, 10 May 2011 18:18:16 +0000
Subject: [EnergyPlus_Support] AHU thermal capacitance? Work around?
Dear All,
I have a night set back heating temperature (15 C) in my one zone building.
I am trying to model the optimal time to change the set point temperature to the occupied time value (30 C) in order to reach the right temperature in the morning when the first building occupant arrives.
However I find this problematic.
The problem is that as soon as I put the set point to 30 C the AHU heating coil starts IMMEDIATELY to supply air at 45 C (maximum supply air temperature to meet the zone heating requirement - SetpointManager:SingleZone:Heating) with no time lag.
The model doesn't take into account the lag due to the time that the heating coil takes to heat up the air in the real word.
I know that for the plant loop it is possible to "play" with the "Plant Loop Volume" parameter in order to consider the system capacitance and impose this time lag to water temperature, I would like to do the same with air temperature in the AHU.
Can anybody suggest any work around for this?
Many thanks in advance!
Andrea
I have a night set back heating temperature (15 C) in my one zone building.
I am trying to model the optimal time to change the set point temperature to the occupied time value (30 C) in order to reach the right temperature in the morning when the first building occupant arrives.
However I find this problematic.
The problem is that as soon as I put the set point to 30 C the AHU heating coil starts IMMEDIATELY to supply air at 45 C (maximum supply air temperature to meet the zone heating requirement - SetpointManager:SingleZone:Heating) with no time lag.
The model doesn't take into account the lag due to the time that the heating coil takes to heat up the air in the real word.
I know that for the plant loop it is possible to "play" with the "Plant Loop Volume" parameter in order to consider the system capacitance and impose this time lag to water temperature, I would like to do the same with air temperature in the AHU.
Can anybody suggest any work around for this?
Many thanks in advance!
Andrea
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