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[EnergyPlus_Support] Re: Fresh Air Issues

Thank you for your response, and access to the ductwork isn't really a problem and this facility is very small. It was originally a large work space/garage which was retrofitted to have a bunch of small "offices" which have ceilings you can climb onto using a ladder (if you were brave enough) and it should be a fairly simple job of installing ductwork. 

So if they did not use 100% FA then where did the supply fan draw it's air from? 

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jim Dirkes" <jim@...> wrote:
>
> Your approach should work well.  
> 
> p.s., Do not specify a return fan and think about how you specify
> infiltration, since the building's internal pressure may offset it somewhat.
> 
> p.p.s., This is not such a "glaring deficiency" as it may first appear. You
> will be avoiding the operating cost associated with duct pressure drop and
> perhaps a return fan, too.  Duct is not cheap, either, especially if
> installed in an existing facility where access is difficult.  
> 
> One of my past jobs was for a manufacturer who routinely used no duct for
> (relatively open) industrial facilities that were >100,000 square feet .
> with great success and amazingly uniform temperatures.  They did NOT use
> 100% outdoor air; rather the controls maintained a very slight positive
> building pressure, essentially countering infiltration.  (Just in case you
> were interested J)
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., BEMP , LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of ntraughpee
> Sent: Friday, October 28, 2011 4:49 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Fresh Air Issues
> 
>  
> 
>   
> 
> Hey Everybody,
> 
> 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.
> 
> 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...
> 
> I was then working on the .expidf and was curious if anybody had a good way
> of doing this using the AirLoop HVAC?
> 
> Basically: what is the best way to model a system with 100% fresh air and no
> return ductwork/relief ductwork
>




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