Question-and-Answer Resource for the Building Energy Modeling Community
Get started with the Help page
Ask Your Question

Revision history [back]

click to hide/show revision 1
initial version

Unit Ventilator Economizer

I have a model in OpenStudio v2.6 with ~50 zones served by a 4-pipe fan coil w/ an economizer. Ventilation to the zones is provided by a central DOAS system. I'm using the Unit Ventilator Object w/ an ON/OFF Fan + Heating and Cooling coils to model the 4-pipe fan coils, and the zones are connected to a central Air loop to model the DOAS.

However, i have been unable to get the economizer on the Unit Ventilator to operate correctly. Ideally the system would operate only in cooling mode and provide a varying amount of outside air depending on temperatures and load. Something like the diagram shown below. image description

At first glance of the description of the Input/Output reference guide, the Variable Percent control seemed to offer the correct control capabilities.

image description

However, the control description further down in the Input/Output reference guide seems to contradict this and says that in both heating and cooling mode, the outside air is set to minimum for both heating and cooling.

image description image description

When I applied the Variable Percentage control to the Unit Ventilator, the system only delivers the minimum outside air and never modulates up based on conditions. Am I using the correct zone equipment/controls I need?

Unit Ventilator Economizer

I have a model in OpenStudio v2.6 with ~50 zones served by a 4-pipe fan coil w/ an economizer. Ventilation to the zones is provided by a central DOAS system. I'm using the Unit Ventilator Object w/ an ON/OFF Fan + Heating and Cooling coils to model the 4-pipe fan coils, and the zones are connected to a central Air loop to model the DOAS.

However, i have been unable to get the economizer on the Unit Ventilator to operate correctly. Ideally the system would operate only in cooling mode and provide a varying amount of outside air depending on temperatures and load. Something like the diagram shown below. image description

At first glance of the description of the Input/Output reference guide, the Variable Percent control seemed to offer the correct control capabilities.

image description

However, the control description further down in the Input/Output reference guide seems to contradict this and says that in both heating and cooling mode, the outside air is set to minimum for both heating and cooling.

image description image description

When I applied the Variable Percentage control to the Unit Ventilator, the system only delivers the minimum outside air and never modulates up based on conditions. Am I using the correct zone equipment/controls I need?

Unit Ventilator Economizer

I have a model in OpenStudio v2.6 with ~50 zones served by a 4-pipe fan coil w/ an economizer. Ventilation to the zones is provided by a central DOAS system. I'm using the Unit Ventilator Object w/ an ON/OFF Fan + Heating and Cooling coils to model the 4-pipe fan coils, and the zones are connected to a central Air loop to model the DOAS.

However, i have been unable to get the economizer on the Unit Ventilator to operate correctly. Ideally the system would operate only in cooling mode and provide a varying amount of outside air depending on temperatures and load. Something like the diagram shown below. image description

At first glance of the description of the Input/Output reference guide, the Variable Percent control seemed to offer the correct control capabilities.

image description

However, the control description further down in the Input/Output reference guide seems to contradict this and says that in both heating and cooling mode, the outside air is set to minimum for both heating and cooling.

image description image description

When I applied the Variable Percentage control to the Unit Ventilator, the system only delivers the minimum outside air and never modulates up based on conditions. Am I using the correct zone equipment/controls I need?