Demand Controlled Ventilation- how the measure works?

I am currently using Openstudio 1.14 on my windows 10 computer, and I have a question about the 'enable demand control ventilation' BCL measure.

I understand how demand control ventilation (DCV) is supposed to work in a real building, but I'm not sure about how it's implemented in Openstudio. I'd like to know, since in the model it seems to have a big impact: my 'baseline' building (2-storey multi-use university building, heat from gas boilers distributed by VAV system) has an EUI of 56kbtu/ft2.

When I apply the 'enable economizer control' measure (fixedenthalpy option) that doesn't change EUI at all, but when I apply DCV it goes all they way down to 39kbtu/ft2.

The thing is, other than selecting the VAV air loop that serves the entire building, I didn't do anything specific to implement the measure- there wasn't any "click here to apply the CO2 sensor to this space" option or anything like that...so how exactly does DCV get implemented by the measure? What is it assuming about locating C02 sensors and calculating the CO2 level (presumably from occupancy & activity space type schedules)?

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gsuscalo

asked 2017-09-13 19:35:02 -0500

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__AmirRoth__

updated 2017-09-14 07:24:37 -0500

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Please always include links to shared resources such as a BCL measure, I don't want to have to look for it if I'm going to help you. Thanks!

Julien Marrec (2017-09-14 03:37:23 -0500) edit

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The measure happens to be here Enable Demand Controlled Ventilation, and it does have a bunch of information that you need to read, especially the measure description.

This measure enable demand controlled ventilation on all or a single air loops in the building. The measure will loop through the selected systems, go into the "control" tab for the air system and toggles the "Demand Controlled Ventilation" button to the "on" position. If the HVAC system does not have an air side system, or if the "Demand Controlled Ventilation" button is already in the "on" position, then the runner sends an info message to the user that the model was not changed. The cost arguments are user arguments that start with a default of $0.

Then I suggest you head towards my answer to the previously asked question How can I model DCV? since that part has already been answered. Short story, it enabled this field in EnergyPlus Controller:MechanicalVentilation>DCV and will vary the outside air based on the actual number of occupants in the space as opposed to the nominal number of occupants.