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

Wed Nov 7 13:58:44 GMT 2007

Just to add my two cents worth: AIOLOS can model single-sided ventilation, including turbulence effects. The latter is modeled from empirical data measured on (if I remember correctly) a single storey building, in what seemed a rural or suburban context. The Phaff (and de Gidds) model also considers turbulence effects, taken from empirical evidence. ... i.e. not sure how applicable this would be for a skyscraper. Both models are detailed in:

Allard, F., K. Limam, et al. (1998). Fundamentals of natural ventilation. Natural Ventilation in Buildings: A Design Handbook. F. Allard. London, James & James: 9-62.

You can also look up:

Dascalaki, E., M. J. Santamouris, et al. (1996). "On the combination of air velocity and flow measurements in single sided natural ventilation configurations." Energy and Buildings 24(1): 155-165.

Dascalaki, E., M. J. Santamouris, et al. (1995). "Predicting single-sided natural ventilation rates in buildings." Solar Energy 55(5): 327-341.

Hope this helps, Denis

   _____  

De: esp-r-bounces at lists.strath.ac.uk de la part de paul strachan
Date: mer. 2007-11-07 07:33
À: 'esp-r at lists.strath.ac.uk'
Objet : [esp-r] Re: air quality assessment for room with natural ventilation

This question came up in comparing results from double facade modelling
in the current IEA34/43 task. The only program taking part which
includes an allowance for turbulence effects was the Dutch program from
VABI. It uses an algorithm from:
Phaff et al., (1980). The ventilation of buildings. Investigation of the
consequences of opening one window on the internal climate of the room,
TNO report C448.

Regards
Paul

> 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 [HYPERLINK "mailto: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

--
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Dr P A Strachan                   email: paul at esru.strath.ac.uk
ESRU, Dept. of Mechanical Eng.          phone: +44 141 548 2041
University of Strathclyde                 fax: +44 141 552 5105
Glasgow G1 1XJ, UK                 HYPERLINK "http://www.esru.strath.ac.uk/"http://www.esru.strath.ac.uk
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