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2016-03-29 21:38:44 -0500 | asked a question | OpenStudio: DOAS won't match Design Specification Outdoor Air rates I'm trying to model a residential tower with HRV's in each suite (approximated with one large air loop with air-to-air HX, supply/exhaust fans, and AirTerminal Single Duct Uncontrolled in each zone). Minimum fraction of O/A has been set to 1.0 via a schedule at the air loop Outdoor Air Controller. I have defined People and Design Specification Outdoor Air rates at the Space Type level. I have also tried setting flags in OS:Sizing:System so that "type of load to size on" is set to VentilationRequirement and "System Outdoor Air Method" is set to VentilationRateProcedure. All fans, intakes, terminals etc are autosized. When I run the model, the resulting airflows are massive (10x what I have defined or more). If I hard-size all the diffusers to the airflow I know I need it works fine. Kind of defeats the purpose of schedules and hierarchies though. I am at a loss. If anyone is able to assist, would be much appreciated. Edit:Link to download OSM file here (thanks Julien & Jamie). I switched a few diffusers in air loop "Residential HRV Loop" back to autosize, most have been left hard-sized for comparison's sake: https://www.dropbox.com/s/7kxqg0u2kxu... Edit2: Here's an example comparison of some of the zones that are autosized airflows vs hardsized flows entered at zone diffuser. Values are taken from the standard OpenStudio reports, Outdoor Air section. As you can see, difference is pretty extreme in some cases from the defined airflow requirements. |
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