[esp-r] Re: bulk air flow network

[Jon Hand]

In ESP-r you define the network to be as simple (at least 3 nodes) or complex (well more than
200 nodes will probably fry your brain) as you want.  If there is no air flow path between two
zone then there is no need to describe such a path.  Indeed it would be perverse to create
such a link.  For example, if you have more than one building in your model you would
create a single flow network that included the flow paths in the two buildings even though
there is no direct link between them.  If there is a floor slab that blocks flow then
there is no need to link the two levels.  And, if there are several different types of
flow between two zones - say a door and a crack and a grill then your network would have
three paths for that part of the model.

Usually the computation resource is not noticable (it is super efficient).  But if you have some large openings and
some very small ones you might want to use a shorter timestep (one or two minutes).  There are
one or two people who like to turn on iteration between the zone and flow solver which does
bog things down but most users run the zone and flow solvers 1:1.

There is a caviat - if you have 20 thermal zones, one almost always has a flow node
for each zone.  Mixing some zones with scheduled air flow and others within a
flow network tends to confuse things.

-Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On Behalf Of Chris Yates [chris at zed-uk.com]
Sent: 09 February 2010 16:39
To: esp-r at lists.strath.ac.uk
Subject: [esp-r]  bulk air flow network

This is just for reference at present, so I’m not hoping for anything more than a quick yes or no:

In the interests of speed, is it possible to tell ESP-r which objects take part in the bulk air flow network apart from those you don’t want to.

I’m spending hours with the simulation program that dare not speak its name running a bulk flow network. Probably 20% of the openings have bulk flow characteristics but I think macroflo calculates every one of them – even when everything is set to zero for that opening. It’d be nice to pick and choose which ones you want calculated.

Thanks

Chris