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[EnergyPlus_Support] Re: Residential Multifamily Infiltration & Ventilation


Hi Alea,

I am at the same stage, I have calculated the ventilation  with the WindandStackOpenArea objects and the results seem to be accetable. But, I am not sure if I have done it correctly estimating the "height difference", I have used one half height of each opening area, in my case, small ventilation openings (no doors, no windows).

Regarding the "height difference", I have read in the ASHRAE fundamentals the next paragraph:

Estimation of "height difference to neutral pressure level" is difficult for naturally ventilated buildings. If one window or door represents a large fraction (approximately 90%) of the total opening area in the envelope, then the NPL is at the mid-height of that aperture, and  height difference to NPL equals one-half the height of the aperture. For this condition, flow through the opening is bidirectional (i.e., air from the warmer side flows through the top of the opening, and air from the colder side flows through the bottom).

I cannot help you too much, I hope someone more expert helps us.

Adrian.






--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "aleagerman22" <agerman@...> wrote:
>
> Hello,
> I am new to Energy+ and am modeling two new construction multi-family buildings. One is 3 stories with exterior entrances and the other is 10 stories with interior hallways. I am struglling with how best to model natural ventilation and infiltration, both due to exhaust fan operation and envelope leakage based on a measured/expected SLA. My zoning is fairly simple with a single zone per apartment unit. This is new construction so the assumption is that envelope sealing is decent and there is not significant connection between the individual units. 
> 
> The AirflowNetwork module appears to be a very powerful tool but perhaps too complex for what I'm trying to do. Also, there are many modeling inputs, like Wind Pressure Coefficients, that I don't have and would have to use defaults or those measured by others which may reduce accuracy. Thoughts? The other alternative appears to be through ZoneVentilation & ZoneInfiltration. However, if I enter my exhaust fans and envelope leakage separately, total infiltration will be a summation of the natural infiltration and mechanical ventilation and will be overestimated according to ASHRAE. 
> Regarding natural ventilation the ZoneVentilation:WindandStackOpenArea appears to be a good option; however, the E+ documentation advises against it because the "height difference" is particularly difficult to estimate. Is the ZoneVentilation:DesignFlowRate to the best way to go?
> 
> I would greatly appreciate any advice or guidance from anyone who has experience with this. Thank you in advance.
> 
> Alea
>



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