If you have a real life system, it can always be simulated in EPlus, with energy usage as an objective..
Hardware operating details are not all simulated in EPlus yet. By this I mean, for example, the fan must come on first before the cooling or heating source is turned on. The fan will remain on for a while after the sources are turned off. If the fan air is interrupted, the gas or oil supply is switched off automatically. Similarly, the gas pilot must be on, before the main jet is turned on. The managers are there, but not easy to use.
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Type 4 dual set point with dead band would eliminate many conflicting cases. OA will let in cold air in the dead band temperature. The cooling coil will never start up. The heating coil may start when the dead band is set below 10°C.
When you have high internal load, the heating would stop, but the zone temperature would continue to rise and turn on the cooling. This can be avoided by adding cool outside air, if available, with is the economizer operation. Economizer always save energy, but it require additinal hardware sensors and controllers.
If you know that the return air temperature is higher than the outside air, the return air should be reduced and the outside air increased. This is why the HRE is not effective in Summer. The temperature of the return air can be higher than that of the outside air.
In Winter, the relief air alone is not effective either. That is the reason why I always suggested to find another waste heat source, such as the boiler chemney.
The warnings can be eliminated by correct scheduling and setpoint control.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Date: Tue, 1 Nov 2011 16:10:20 +0000
Subject: [EnergyPlus_Support] ASHRAE 90.1 Baseline system with no economizer serving a high internal load area
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Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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Hardware operating details are not all simulated in EPlus yet. By this I mean, for example, the fan must come on first before the cooling or heating source is turned on. The fan will remain on for a while after the sources are turned off. If the fan air is interrupted, the gas or oil supply is switched off automatically. Similarly, the gas pilot must be on, before the main jet is turned on. The managers are there, but not easy to use.
======================================
Type 4 dual set point with dead band would eliminate many conflicting cases. OA will let in cold air in the dead band temperature. The cooling coil will never start up. The heating coil may start when the dead band is set below 10°C.
When you have high internal load, the heating would stop, but the zone temperature would continue to rise and turn on the cooling. This can be avoided by adding cool outside air, if available, with is the economizer operation. Economizer always save energy, but it require additinal hardware sensors and controllers.
If you know that the return air temperature is higher than the outside air, the return air should be reduced and the outside air increased. This is why the HRE is not effective in Summer. The temperature of the return air can be higher than that of the outside air.
In Winter, the relief air alone is not effective either. That is the reason why I always suggested to find another waste heat source, such as the boiler chemney.
The warnings can be eliminated by correct scheduling and setpoint control.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Date: Tue, 1 Nov 2011 16:10:20 +0000
Subject: [EnergyPlus_Support] ASHRAE 90.1 Baseline system with no economizer serving a high internal load area
Dear Forum,
For certain climates, ASHRAE 90.1 specifies that an economizer is not required for the Baseline system.
If the system serves an internal load-dominated space such as an assembly area or meeting rooms, you:
* need the (DX) cooling coil to maintain comfort
* run into millions of warnings when your DX coil runs to provide cooling in the cool months. With modest (or greater)amounts of outdoor air for minimum ventilation needs, the DX coil sees a low entering temperature and attempts to cool it .... producing near freezing discharge temperatures.
So.... I'm wondering how you have dealt with this situation.
1) Do you live with the warnings?
2) Add an economizer (and live with the lesser savings compared to Proposed)?
3) Something else?
Thanks in advance! I appreciate all of your input.
For certain climates, ASHRAE 90.1 specifies that an economizer is not required for the Baseline system.
If the system serves an internal load-dominated space such as an assembly area or meeting rooms, you:
* need the (DX) cooling coil to maintain comfort
* run into millions of warnings when your DX coil runs to provide cooling in the cool months. With modest (or greater)amounts of outdoor air for minimum ventilation needs, the DX coil sees a low entering temperature and attempts to cool it .... producing near freezing discharge temperatures.
So.... I'm wondering how you have dealt with this situation.
1) Do you live with the warnings?
2) Add an economizer (and live with the lesser savings compared to Proposed)?
3) Something else?
Thanks in advance! I appreciate all of your input.
__._,_.___
Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx
The primary EnergyPlus web site is found at:
http://www.energyplus.gov
The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/
Attachments are currently allowed but be mindful that not everyone has a high speed connection. Limit attachments to small files.
EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
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