[BLDG-SIM] natural ventilation analysis tools

Graham & Megan hamnmegs at ozemail.com.au
Wed Oct 22 03:20:39 PDT 2003


natural ventilation analysis toolsTo add to Jon Hand's comments.  

I have used Apache (IES) successfully for the assessment / design of natural ventilation systems.  While I am not an expert with TAS, it appears to offer very similar functionality to IES based on my limited experience with it.  Both offer multi-zone bulk airflow modelling combined with the dynamic thermal simulation.  CFD is typically used to gain a greater insight into local air temperatures and airflow at one point in time where bulk airflow provides a zone average otherwise.  Increasingly some consultants are using CFD for transient simulations.  The Swiss Reinsurance building in London (The Ghurkin) I believe was designed using CFD exclusively by Hilson-Moran.  While some CFD packages are now claiming to account for the transient radiant loads, I am doubtful whether this would provide as useful of a tool as bulk airflow modelling - this will change ...

In terms of useful and correct results, there has been BESTesting and some validation of these tools from real buildings.  In my experience you need to be very careful to declare results in absolute terms.  There are so many variables beyond our control and the biggest one, the weather, drives when natural ventilation systems are useful.  A sensitivity study of key variables to understand the risks and thus where better information and additional design is needed to be confident, is essential.


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