My point was that you cannot mix the infiltration object in conjunction with the AFN.�� If you want to model infiltration with the AFN, you have to define the leakage characteristics of the space for the AFN�� (this should probably be done anyway for proper modeling - in fact, all these AFN programs such as COMIS and AirNet were originally designed not for modeling natural ventilation, but rather infiltration).��
Sure, you can use a blower door test to get the leakage fraction, but that has to be used as an input to the AFN, not to the infiltration object.���� I've always been adverse to modeling infiltration as a constant air change rate, because that's nonphysical and not what really happens.�� IMHO, it's always much better to define the physical characteristics of the space (leakage-fraction, area of cracks, etc.) and then use a physical model like the Sherman-Grimsrud or the AFN to then compute the hour-to-hour infiltration.
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 108D Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://weather.whiteboxtechnologies.com for simulation-ready weather data (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 3/10/2013 9:25 AM, Oscar Hernandez wrote:
There are many methods to calculate the real infiltration value...like the blower test.
On Oct 3, 2013 6:06 PM, <josep.sole@xxxxxxxxxxx> wrote:
��
In AFN models you need to assume a lot of other hypothesis it is no easier than assume the zone infiltration rate.
��
Josep Sol��
URSA Insulation S.A-Sustainibility & Technical Manager��
M��vil +34 606 42 32 14
��
P URALITA / URSA se compromete con el ahorro de energ��a. Antes de imprimir este mensaje aseg��rese de que es necesario.��
De: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] En nombre de Oscar Hernandez
Enviado el: jueves, 03 de octubre de 2013 17:57
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Asunto: Re: [EnergyPlus_Support] Using AFN for windows, but with default infiltration��
��
If you want to model an infiltration value use the zone infiltration. The AFN its to predict the infiltrattion value when you don"t know it.
��
On 3 October 2013 17:42, Joe Huang <YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx> wrote:
��
I don't think the infiltration objects can be used in conjunction with the AFN. That would violate the mass balance of the AFN, wouldn't it?
Sent from my IPad��
Joe Huang
��
On Oct 3, 2013, at 8:35 AM, Oscar Hernandez <eng.ohw@xxxxxxxxx> wrote:��
Hi,
Use the zone infiltration.
Oscar
On Oct 3, 2013 2:48 PM, "allinson_louis" <allinson_louis@xxxxxxxxxxx> wrote:
��
Hi All
I am using AFN to model air flow through window openings that I am controlling using EMS
However, when the windows are closed the only infiltration is through cracks and the infiltration is much less than 0.1ach. I want to model a 'default' 0.1ach when the windows are closed, as this is a typical value used in simulations.
Is this possible?��