Question-and-Answer Resource for the Building Energy Modeling Community
 | 1 | initial version |
In order to have your free cooling running you need to go to your HVAC tab and select the OS:Controller:OutdoorAir of the air loop serving your zone as shown below
Here you need to set the economizer control type to "FixedDewPointAndDryBulb". Then use the limits of your free cooling which are 23°C Dry bulb temperature and 19.366°C Dew Point(which gives 80% RH at 23°C DB) in your case. There is no limit for RH so you need to see if this works for your case for example during winter. Finally, use the Air System Outdoor Air Limiting Factor output variable to see when economizer is used. When the output is 2 then "Economizer is active and sets the flow greater than the minimum outdoor air fraction".
The 100% outdoor air in your comment is a sizing option for your coil and does not represent the free cooling.
| | 2 | No.2 Revision |
In order to have your free cooling running you need to go to your HVAC tab and select the OS:Controller:OutdoorAir of the air loop serving your zone as shown below
Here you need to set the economizer control type to "FixedDewPointAndDryBulb". Then use the limits of your free cooling which are 23°C Dry bulb temperature and 19.366°C Dew Point(which gives 80% RH at 23°C DB) in your case. There is no limit for RH so you need to see if this works for your case for example during winter. Finally, use the Air System Outdoor Air Limiting Factor output variable to see when economizer is used. When the output is 2 then "Economizer is active and sets the flow greater than the minimum outdoor air fraction".
The 100% outdoor air in your comment is a sizing option for your coil and does not represent the free cooling.cooling. As far as when your cooling coil operates you should also check if the zone temperature is above your thermostat and not the outside temperature
