[esp-r] Re: air flow network

[Jon Hand]

If you are solving air flow via a flow network then the flow rate through a component
such as a crack will be related to the driving forces at each simulation time step.  So
it is correct that the predicted flow through the crack will be different from a static
assumption about flow. 

-Jon Hand
________________________________________
From: esp-r-bounces at lists.strath.ac.uk [esp-r-bounces at lists.strath.ac.uk] on behalf of Arianna Sdei [A.Sdei at brighton.ac.uk]
Sent: 29 November 2013 14:36
To: apinto at lnec.pt; Achim Geissler
Cc: esp-r at lists.strath.ac.uk Club
Subject: [esp-r] Re: air flow network

Hi All,

Do you know why if I ask ESP-r to calculate the volume flow rate through the cracks and I average it annually that doesn't correspond to the volume flow rate that I calculate manually using the equation : (Afacade X ACH50 X Vol/sumAfacade)/3600? The manual calculaton gives me actually a higher value, almost double. Do I need to refine the calculation? Or calculate the error?

Let me know,

Thank you in advance,

Best

Arianna

-----Original Message-----
From: esp-r-bounces at lists.strath.ac.uk [mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of apinto at lnec.pt
Sent: 28 November 2013 20:06
To: Achim Geissler
Cc: esp-r at lists.strath.ac.uk Club
Subject: [esp-r] Re: air flow network

Hi,

For each facade are you using something like:
a= ACH50 x VOL/(50^0.66)/3600/Sum(Afacade) x Afacade i ?

To refine the calculation, in each façade you should split “a” for an upper and lower part.

Best
Armando

> Hi Arianna,
>
> could you give an example with numbers and units for your substitution
> procedure? What was the ACH at 50 Pa result from the measurement? Do you
> have consumption data from the obviously existing building? What are
> the dimensions of the single storey house? At 100 m2 heated area you
> would end up with 300 kWh/(m2 a) which is a lot but not totally
> impossible depending on climate, window sizes, insulation standard and leakiness.
>
> Sorry to ask so many questions.
>
> Best
> Achim
>
>
> On Nov 28, 2013, at 8:37 PM, Arianna Sdei <A.Sdei at brighton.ac.uk> wrote:
>
>> Dear ESP-r community,
>>
>> I am trying to set up an air flow network using the measured air flow
>> rate from pressure tests. To do that I am substituting power law flow
>> components to cracks. I have calculated the coefficient a in the
>> equation : Q = a dP ^b using the measured ACH and I am using b=0.66
>> but when simulating I get a too high heating load (over 30000
>> kWh/year for a single storey house) . Does anybody know why this
>> happens and if there is another way to use the measured ACH from the
>> pressure tests to set up the infiltration rate using an air flow
>> network? Thank you
>>
>> Regards,
>>
>> Arianna
>>
>> Arianna Sdei
>>
>> Research Fellow IFORE (Innovation For Renewal)
>>
>> UNIVERSITY OF BRIGHTON
>>
>> Moulsecoomb, Lewes Road, Brighton, BN2 4AT
>>
>> direct line: 0044 (0)2036747268
>>
>> mobile: 0044 (0)7981739024
>>
>>
>>
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> achim.geissler at intergga.ch
>
>
>
>
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