Hi, Jeannie
I am not sure whether you are referring the thermostat in EPlus or a real thermostat.
A real thermostat is usually a Ton and Toff switch. In BAS, sensors are used for the program, but real thermostats are used for fail safe operations.
The EPlus zone thermostat is not really a thermostat. It is a setpoint register. The zone mean air temperature is computer to satisfy this value, balancing the cooling and heating load.
The type 4 thermostat can be implemented by two mercury switch thermostats, AND connecting the two cold and two hot switches to generate the dead band, the two units are in opposite states. (neither cool or heat would be on.)
Many control components are not simulated in EPlus. The time delay, and some other features are now slowly added in the new versions. This is one reason why new users have more problem in filling in the IDF directly.
Your opening statement seems to referring to the common air thermostat switch with a setting lever. It does not have a "dead band", and has a set back range and usually has a heat and cool selection to use either one of the switch in the same mechanism. (Ton1L and Toff1H, or Toff2L and ton2H.). Two of these (Four contacts) can produce a dead band.
In BAS, the zone temperature values are collected with sensors. They are processed and then acted on with the VAV diffusers or duct temperature control. The total load for one system is optimized with different plant equipment changes.
For example, to provide safety of the system, the boiler will have over heat warning and automatic burner shut off with a hard wired thermostat mounted at the boiler. Usually, the BAS will generate a warning and control the situation without the safety devices being operated.
Because of the connecting wires and power requirements, some local hardware gravity operated system are usually involve for added safety requirement. Eplus has the maximum design temperatures, etc. these will require additional equipment, but need not be present in the normal energy usage simulation.
In general, a central BAS is an information collection, monitoring, and display system and can provide customed adjustment to the control zones as the environment changes, via a remote control system. The installed system can normally operate under local BAS or manual control, without the central BAS monitoring being in active control.
I have seen a few systems in operation, but have never design one.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Mon, 27 Feb 2012 09:50:32 +0000
Subject: [EnergyPlus_Support] Thermostat Control and the BAS
__._,_.___
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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I am not sure whether you are referring the thermostat in EPlus or a real thermostat.
A real thermostat is usually a Ton and Toff switch. In BAS, sensors are used for the program, but real thermostats are used for fail safe operations.
The EPlus zone thermostat is not really a thermostat. It is a setpoint register. The zone mean air temperature is computer to satisfy this value, balancing the cooling and heating load.
The type 4 thermostat can be implemented by two mercury switch thermostats, AND connecting the two cold and two hot switches to generate the dead band, the two units are in opposite states. (neither cool or heat would be on.)
Many control components are not simulated in EPlus. The time delay, and some other features are now slowly added in the new versions. This is one reason why new users have more problem in filling in the IDF directly.
Your opening statement seems to referring to the common air thermostat switch with a setting lever. It does not have a "dead band", and has a set back range and usually has a heat and cool selection to use either one of the switch in the same mechanism. (Ton1L and Toff1H, or Toff2L and ton2H.). Two of these (Four contacts) can produce a dead band.
In BAS, the zone temperature values are collected with sensors. They are processed and then acted on with the VAV diffusers or duct temperature control. The total load for one system is optimized with different plant equipment changes.
For example, to provide safety of the system, the boiler will have over heat warning and automatic burner shut off with a hard wired thermostat mounted at the boiler. Usually, the BAS will generate a warning and control the situation without the safety devices being operated.
Because of the connecting wires and power requirements, some local hardware gravity operated system are usually involve for added safety requirement. Eplus has the maximum design temperatures, etc. these will require additional equipment, but need not be present in the normal energy usage simulation.
In general, a central BAS is an information collection, monitoring, and display system and can provide customed adjustment to the control zones as the environment changes, via a remote control system. The installed system can normally operate under local BAS or manual control, without the central BAS monitoring being in active control.
I have seen a few systems in operation, but have never design one.
Dr. Li
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: jeannieboef@xxxxxxxxx
Date: Mon, 27 Feb 2012 09:50:32 +0000
Subject: [EnergyPlus_Support] Thermostat Control and the BAS
Dear Group,
As I understand it, a thermostat will output a signal based on the monitored drybulb and the set Set Point. There are different types, but mainly we use duel set point for heating and cooling with deadband.
The question is, how does this tie in with the central control at the BAS which takes into acount ODA rates, humidities and heating and cooling loads from numerous zones and relays the appropriate signals to one or more AHU and other zone equipment, as well as heating and cooling plant equipment.
I would have thought that a BAS doesn't need thermostats in the classical sense, because Set Points for ODA, RH, Htg and Clg Setpoints, CO2, etc. are centrally assigned on the computer system, and only sensors are needed in the zones for the various properties.
Does anyone have experience on typical control methodologies incorporating BAS?
Regards,
Jean.
As I understand it, a thermostat will output a signal based on the monitored drybulb and the set Set Point. There are different types, but mainly we use duel set point for heating and cooling with deadband.
The question is, how does this tie in with the central control at the BAS which takes into acount ODA rates, humidities and heating and cooling loads from numerous zones and relays the appropriate signals to one or more AHU and other zone equipment, as well as heating and cooling plant equipment.
I would have thought that a BAS doesn't need thermostats in the classical sense, because Set Points for ODA, RH, Htg and Clg Setpoints, CO2, etc. are centrally assigned on the computer system, and only sensors are needed in the zones for the various properties.
Does anyone have experience on typical control methodologies incorporating BAS?
Regards,
Jean.
__._,_.___
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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