Modelling dehumidification with Simple HVAC in DesignBuilder for a hot-humid climate
Hi everyone, I am modelling an office building in DesignBuilder in a hot-humid climate. The real HVAC system is a CAV chilled-water system with traditional dehumidification: air is cooled to remove moisture and then reheated using electric reheat to reach the required supply temperature. My main issue is dehumidification. I want to know whether this can be represented using Simple HVAC in DesignBuilder, or whether Detailed/Advanced HVAC is required. In Simple HVAC, I used the following settings: Enabled humidity control / dehumidification in the HVAC tab using the humidistat. Set the RH dehumidification setpoint to 70% in the Activity tab. The result is that cooling energy increases, but zone humidity is still not controlled properly. Zones still have RH between 70–80% during occupied hours. Also, there is no reheat energy consumption.
My questions are: Can Simple HVAC with humidity control properly model dehumidification for a CAV chilled-water system? Or should this system be modelled using Detailed HVAC?
Thank you.
Try checking:
Schedules of occupation and refrigeration availability: Both have to be ON to control humidity.
"Minimum supply air delivery temperature", in the simple HVAC tab. In a very humid place, this value might need to be lowered from the default 14oC. Same with "Minimum supply air humidity ratio".
In the model options tab do "Data-HVAC-Sizing=Adequate". As you can see here (https://designbuilder.co.uk/helpv7.3/...) in the "Technical description" tab, other sizing modes use only temperatures in simple HVAC and might undersize for dehumidification