[esp-r] Re: air quality assessment for room with natural ventilation

[Jeremy Cockroft]

I think the question is: does ESP-r have the capability to model bi-directional airflow through an open window into a zone that is substantially sealed from other zones in the building.  A common question and the answer (short of invoking the CFD domain) is no - the bi-directional flow component was originally developed to model tall vertical openings, typically doors, between zones, with bouyancy driven airflows in either direction.  It does not take account of wind turbulence effects that will drive bi-directional airflow at an open window, which is what is missing for this application.  Modelling as two orifices won't help - they will both see the same external pressure node.

This topic has been researched (I co-authored a paper on this in the '70s) but to my knowledge no-one has coded such functionality into any zonal dynamic modelling tool ... but I might be mistaken ...

Jeremy

-----Original Message-----
From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Aizaz Samuel
Sent: 07 November 2007 10:25
To: Pueltz, Gunter
Cc: esp-r at lists.strath.ac.uk
Subject: [esp-r] Re: air quality assessment for room with natural ventilation

Contaminant modelling works with bi-directional flow components just as with other components and you probably will end up with more CO2 going out of the zone as coming into it provided there are local CO2 sources (metabolic rates
maybe) defined within the zone. I have never made a model with bi-directional components though and would fall back on Jon's recommendation if it does not work.

There is no provision yet to show the mass flow of contaminant along each flow path because only concentration for each node is stored in the results library. It should be possible to obtain this information by post processing node concentrations and air flow rates 

-Aizaz

On Wednesday 07 November 2007 07:06, Jon Hand wrote:
> A bi-directional component might be replace by two common orifice 
> components (suitably placed to represent the upper and lower portion 
> of the window).
> That should allow the CO2 to 'see' the flow in.
>
> Whether the CO2 bookkeepping could be revised to allow it to track 
> both paths of a bi-directional component is something Aizaz might 
> advise on.
>
> -Jon
>
>
> -----Original Message-----
> From: Pueltz, Gunter [mailto:Gunter.Pueltz at MuellerBBM.de]
> Sent: Wed 11/7/2007 6:38 AM
> To: 'esp-r at lists.strath.ac.uk'
> Cc: Aizaz Samuel; Jon Hand
> Subject: air quality assessment for room with natural ventilation
>
> Dear ESP-r developers,
>
> currently I have a simulation job for an office building, which shows 
> only natural ventilation (NO mechanical ventilation) by openable windows.
> In Summer the rooms are cooled by chilled ceilings.
>
> Now my client wants infos about the indoor air quality, which can be 
> obtained by the window ventilation.
> I do know, that ESP-r shows the ability to calculate CO2-concentrations.
> This is a good facility to assess indoor air quality, as CO2 is 
> representing air quality very well.
> But my last knowledge of this contaminant calculations in ESP-r was, 
> that for a flow component with BI-DIRECTIONAL air flow (typical for an 
> open
> window)
> only the net-flow is taken into account for the CO2-balance in ESP-r.
> The net-flow of an open window of one single room always is zero - so 
> this approach do not work for a room with single-sided window 
> ventilation.
> Or - in other words - the reduction of CO2-concentration in a room by 
> a bidirectional airflow through an open window can not be calculated so far.
>
> Currently I am using ESP-r, version 11.3: Does this (or a future ?) 
> version show the ability to assess indoor air quality in rooms with 
> natural ventilation (which means BI-DIRECTIONAL air flow must be taken 
> into account completely) ?
>
> Best regards,
> Gunter
>
> --
> Dr. Gunter Pültz
>
> Müller-BBM GmbH
> Robert-Koch-Straße 11
> 82152 Planegg
> Telefon +49 (0)89 85602 - 336
> Telefax +49 (0)89 85602 - 111
> http://www.MuellerBBM.de
>
> HRB München 86143
> Geschäftsführer: Bernd Grözinger, Dr. Edwin Schorer, Norbert Suritsch

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