[Bldg-sim] Natural Ventilation

Chris Yates chris.malcolm.yates at gmail.com
Thu Feb 10 00:51:58 PST 2011


Shambav,

It would be helpful to know more about what you want to achieve with 
natural ventilation. In order of precedence:

   1. How temperate is the climate? The climate needs to be fairly
      temperate. Most of the UK will be ok for natural vent in many
      commercial buildings. The same is not true for the South of France!
   2. How heavily used is the building? Forget natural ventilation if a
      building has dense occupancy or high IT loads.
   3. If rules of thumb are followed (e.g. 5% of floor area reflected as
      openable area, thermal mass, floor depth to ceiling height ratio,
      glazing!) this is a good starting point for the design
   4. A zonal (not CFD) model will allow you to assess the performance
      of the design against weather data and standards such as ASHRAE
      55. Zonal models are computationally cheaper than CFD and will
      help consider strategies such as night time purge ventilation and
      optimisation of thermal mass.
   5. Finally, if you're doing something really unusual or bespoke (like
      working for Norman Foster) CFD may be warranted. Boundary
      conditions such as surface temperatures and flow through openings
      can be extracted from a "snapshot" of the zonal modelling. You may
      want to choose more than one design day to cover variations in
      climate and use (e.g. still days when there is little wind to
      drive ventilation).

Regards

Chris

On 10/02/2011 06:05, Cheney wrote:
> Hi Sambhav,
>
> For natural ventilation analysis, you may start with some field 
> measurements or wind tunnel test  which can help you decide the 
> boundary condition precisely. Some key parameters, such as prevailing 
> wind direction, representative wind speed, air temperatures, surface 
> temperatures, etc. are all important components of the boundary 
> condition. Meanwhile, building geometry, building materials, 
> surrounding buildings, topography, etc. may influence the boundary 
> condition significantly. You will have a holistic consideration of all 
> these variables and make reasonable simplification to work out the 
> boundary condition.
>
> Regards,
> Cheney
> LinkedIN @ http://ca.linkedin.com/pub/yu-cheney-chen/27/637/72b
>
>
>
> On Wed, Feb 9, 2011 at 8:54 PM, sambhav tiwari 
> <tiwari.sambhav at gmail.com <mailto:tiwari.sambhav at gmail.com>> wrote:
>
>     Hi All,
>              Does any one know how to model natural ventilation using cfd
>     tools  like fluent anysis  starccm+ etc and what should be the
>     boundary conditions applicable for natural ventilation in room.
>
>     Thanks
>     Sambhav
>     _______________________________________________
>     Bldg-sim mailing list
>     http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
>     To unsubscribe from this mailing list send  a blank message to
>     BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG
>     <mailto:BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG>
>
>
>
> _______________________________________________
> Bldg-sim mailing list
> http://lists.onebuilding.org/listinfo.cgi/bldg-sim-onebuilding.org
> To unsubscribe from this mailing list send  a blank message to BLDG-SIM-UNSUBSCRIBE at ONEBUILDING.ORG

-- 

Chris Yates C Eng MCIBSE

/Building Physics Consultant/

Tel:+447960731576

Email: chris.malcolm.yates at gmail.com

Skype: christopher.m.yates

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/bldg-sim-onebuilding.org/attachments/20110210/1ce47845/attachment-0001.htm>


More information about the Bldg-sim mailing list