RE: [EnergyPlus_Support] Re: Fresh Air Issues

If the AHU is not a two duct system, one in and one out, i.e., the inlet side has two ducts, one is through the wall one is an open hole to the indoor air. This is already a standard OA mixer box.

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: matthew.sverre.anderson@xxxxxxxxx
Date: Mon, 31 Oct 2011 20:12:48 +0000
Subject: [EnergyPlus_Support] Re: Fresh Air Issues

This is a real building with a constant volume air handler and three dampers that proportionally modulate air flow to the different zones. I use the term "proportionally modulate" in pretty loose terms there since the system is pneumatic, we have no plans, and I was born after dinosaurs walked the Earth so it is difficult for me to figure out exactly how the system operates. (By proportionally modulate it looks like the dampers are linked in such a way that 33% air flow goes to one zone, 33% to the 2nd, 33% to the 3rd and if one zone needs more it can shift to lets say 60%, 20%, 20%).

One of my ideas is to put in some sort of return air system to cut down on the energy consumption which is currently 445 kBTu/SF. Obviously we will update to electronic controls and eliminate leaky valves etc...

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, YuanLu Li <yli006@...> wrote:
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> Are you talking about a real building or something you dream up in your IDF?
> Dr. Li
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> From: matthew.sverre.anderson@...
> Date: Fri, 28 Oct 2011 20:49:18 +0000
> Subject: [EnergyPlus_Support] Fresh Air Issues
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> Hey Everybody,
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> So I am currently trying to model a building for energy analysis. One glaring deficiency is that the building only pulls 100% fresh air, and there is no return air ductwork or economizer. This is obviously a glaring issue that I want to fix, however I am currently at a loss as exactly how to do this or if there are any work-arounds that will let me do it in a an easy manner.
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> Basically, my initial plan was to try to fenagle something in HVAC Templates where I set the fan CFM @ what it is measured at (ie 10,000 CFM) then set the max/min outdoor air @ the same CFM rate so that EnergyPlus is just assuming 100% FA all day, every day (such that it would be leaving via the relief air ductwork). Is this the best way to do it? In reality there is no relief air ductwork since the system just pressurizes the building and forces air out of the cracks etc...
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> I was then working on the .expidf and was curious if anybody had a good way of doing this using the AirLoop HVAC?
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> Basically: what is the best way to model a system with 100% fresh air and no return ductwork/relief ductwork
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