[esp-r] Re: Is network flow necessary for a model to calculate load correctly, even there is only small crack infiltration?

[Jon Hand]

Some ESP-r uses prefer to include air flow networks in their models to represent
the mixing between rooms (via open doors) or open plan office spaces which
have been represented as multiple thermal zones.  In other cases air flow
networks might be of interest to account for the influence of wind direction
and speed on infiltration rates (in comparison to scheduled air flow).

The comment about creating connections between all nodes -  a sketch of the
network would be helpful.  If a network has 5 nodes it is not necessary that each node is
connected to every other node.  If there is zero flow through the north
window then there does not need to be a connection through the north
window.  In reality all windows have small cracks and many flow networks
describe such cracks.  And if you look at the exemplar model 3_windows you
will see that there are several ways to define air flow associated with windows.

And yes, the addition of air flow calculations can change the energy predictions
within a model - whether the changed predictions are correct depends on whether the model
is correct.  What, specifically is different about the performance predicted
for the model with and without a flow network?  How does the zone energy
balance change?  What is the difference in the reported infiltration and ventilation?

Assuring the quality of a model usually involves getting other professionals
to review a model.  And ESRU and other groups offer such services for a consulting fee.

The inclusion of additional analysis in a model (for example surface viewfactors calculations
or air flow networks) should be judged on a case-by-case basis.  What do you imagine
might be happening within the building?  Is this well represented by default assumptions
or is more detail required?

-Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] On Behalf Of 王菊花 [luckygrass100 at hotmail.com]
Sent: 25 May 2010 10:29
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] Is network flow necessary for a model to calculate load correctly, even there is only small crack infiltration?

Dear all,

       I found longer time I use Esp-r,more questions turn up.Even sometimes the questions are all simple but necessary need known by users.

       This time,I wonder if a network flow is necessary for a model to calculate load correctly.I have built a model and found that even I add a network flow with small opening componets to connect nodes,the load simulation results change greatly comparing to that of model without network flows.Further,whether we must build connections for every nodes.Take an example,I just open the south window of the model,with the north window closed.I connect the south boundary node to the internal node with opening component and don't consider the north boundary node.Is this OK？

        Thank you for your kind answers in advance.



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