[esp-r] Re: max ACH

[Jon Hand]

A question about air changes....
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is there a way to set the maximum air changes per hour in case of using openable windows?
I get unrealistic ventilation rates even in case I limit the fraction to 10%. furthermore, limiting the fraction to 0.1 or 0.01 does not affect the AC/h.
Any suggestions are greatly appreciated!

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The first issue is to consider what constitutes a unrealistic ventilation rate. With a bit of a breeze
and windows open it would not be surprising to get 30-40 ach from certain wind directions.

The components we select to represent openings can be a factor.  An air flow component that
is a simple opening is a common orifice with a discharge factor of ~.65.  And many real openings
could offer much more resistance to air flows so you might want to force a smaller DF.  Insect
screens slow it down even more.

The reported changing of the fraction from 0.1 to 0.01 having no impact is not what I would
expect.  Just to confirm that it is not a reporting issue also have a look at the volume flow
rate along several of the flow paths before and after this change.  It might also be worth
turning on the trace for the network flow to get an overall view of flows at each timestep.

There is a control which can act on delta P.  One could conceivably use this to limit flows
and it might be possible to define a control that sensed wind velocity e.g. close the window
in high winds.

I don't think that anyone has considered implementing a flow control that is based on
limiting a volume or mass flow rate.  Might be worth thinking about.

-Jon Hand