How to Model Demand Control Ventilation - DCV in eQUEST

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DCV-1 Partial

In this tutorial, we’re going to cover how to set up demand control ventilation in eQuest. With the first method, the first thing we need to do is we need to go to the Air-Side HVAC. We’re already there, the Air-Side HVAC module. We’ll just click on an air handling unit.

We’re going to go to outdoor air. We want to go to the minimum outdoor air control method. It starts, and defaults to “fraction of design flow,” as you can see in green. There’s a DCV return sensor and a DCV zone sensor. Typically, we would choose the DCV zone sensors, that way it’s based on individual zones. The next thing that is the, probably, common confusion point here, is the select the sizing method. 

We can set the critical zone, but typically you’ll want to set the sum of zone outdoor air. The critical zone method has some rather cumbersome math behind it, and it t doesn’t seem to work well in eQuest. If you’re an expert, and even then, it probably is not going to work that well. So you’ll just want to use the sum of the zone outdoor air. The math will make a lot more sense that way.

We click “done” here, and then we need to have a zone that has the man-controlled ventilation. I just picked the first one. We want to go to air flow, and the minimum flow control. This is how you’re going to control the air here. If you want to hit the Help option, you can always right-click. But, we’re going to select VCV reset up/down. That gives us the option to increase or decrease the amount of outdoor air. 

You need to do this for all of your zones that have DCV for it to have any substantial impact. When you do that, we can run the simulation and verify whether or not we saved energy using DCV, and that’s all there is to the first method of running DCV.