Re: [EnergyPlus_Support] Re: AFN - how to set up air tightness of envelope

On Mon, Oct 31, 2011 at 9:15 AM, Jim Dirkes <jim@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Dear Jean,
A mon avis?..Infiltration is impossible to define in a way that matches reality unless you have a LOT of measured data along with the corresponding wind speed and direction data.

I generally decide that infiltration is acceptably modeled using:

ZoneInfiltration:DesignFlowRate

Name
Infiltrn_ZoneName

Zone Name

02-12-North

Schedule Name
SchCpct_AlwaysOn

Design Flow Rate Calculation Method

AirChanges/Hour

Design Flow Rate
MT

Flow per Zone Floor Area

MT

Flow per Exterior Surface Area
MT
Air Changes per Hour
0.3

Constant Term Coefficient

0.606

Temperature Term Coefficient
0.03636
Velocity Term Coefficient
0.1177

Velocity Squared Term Coefficient

0

The ?Air Changes per Hour? value is a guess based on the construction quality, but I will normally use <= .3 for new construction. For interior zones, I?ll sometimes use 0 or delete the infiltration object.

The coefficients came from the IO Reference (I think) and are leftovers from the DOE or BLAST programs which modify the infiltration amount based on wind speed. Since infiltration is affected by wind speed, it seems appropriate to vary infiltration according to wind speed.

The Building Performance Team
James V. Dirkes II, P.E., BEMP , LEED AP
1631 Acacia Drive NW
Grand Rapids, MI 49504
616 450 8653

From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Lixing Gu
Sent: Monday, October 31, 2011 11:07 AM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: RE: [EnergyPlus_Support] Re: AFN - how to set up air tightness of envelope

Jean:

I am curious to know what is your definition of "a real life realistic
infiltration character of the building". Do you know a real building has a
constant infiltration rate of 0.3 ACH?

Lixing

-----Original Message-----
From: EnergyPlus_Support@xxxxxxxxxxxxxxx
[mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
Sent: Saturday, October 29, 2011 4:34 PM
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Subject: [EnergyPlus_Support] Re: AFN - how to set up air tightness of
envelope

That answer is good, but now I should build in a fan to pressurize my
building to 50 Pa and monitor what volume flow is reported, gradually
increasing the parameter you suggested until the volume flow equals 0.3 ACH
for the building which reflects a realistic building envelope sealing?

I guess what I'm saying is that even with knowing which parameters will
increase or decrease the infiltration rates, I still have no idea how to set
up the system to reflect a real life realistic infiltration character of the
building.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Lixing Gu <gu@...> wrote:
>
> If the AirflowNetwork:MultiZone:Component:DetailedOpening objects are
used,
> you may adjust the values of the Air Mass Flow Coefficient When Opening is
> Closed field.
>
> Hope this helps.
>
> Lixing
>
> -----Original Message-----
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
> Sent: Thursday, October 27, 2011 2:09 PM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] AFN - how to set up air tightness of
envelope
>
> Design Builder has generated me a wonderfully large AFN. As default, all
my
> windows are closed all the time.
>
> 1) How do I realistically define an "air tightness" for windows that don't
> open?
> 2) For windows that do open, but are closed.
>
> using AFN object fields such as minimum crack opening factor, etc.
>
>
----------------------------------------------------------
> ---
>
> I'm thinking of increasing the minimum crack width untill my zones are
> reporting infiltration rates of about 0.35 ACH (well sealed building).
> Then I can add extra infiltration by playing with the openable windows and
> their schedules.
>
>
>
> ------------------------------------
>
> Primary EnergyPlus support is found at:
> http://energyplus.helpserve.com or send a message to
> energyplus-support@...
>
> The primary EnergyPlus web site is found at:
> http://www.energyplus.gov
>
> The group web site is:
> http://groups.yahoo.com/group/EnergyPlus_Support/
>
> Attachments are currently allowed but be mindful that not everyone has a
> high speed connection. Limit attachments to small files.
>
> EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
> Documentation link and press the "search" button.
> Yahoo! Groups Links
>

------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to
energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a
high speed connection. Limit attachments to small files.

EnergyPlus Documentation is searchable. Open EPlusMainMenu.pdf under the
Documentation link and press the "search" button.
Yahoo! Groups Links

	ZoneInfiltration:DesignFlowRate
Name	Infiltrn_ZoneName
Zone Name	02-12-North
Schedule Name	SchCpct_AlwaysOn
Design Flow Rate Calculation Method	AirChanges/Hour
Design Flow Rate	MT
Flow per Zone Floor Area	MT
Flow per Exterior Surface Area	MT
Air Changes per Hour	0.3
Constant Term Coefficient	0.606
Temperature Term Coefficient	0.03636
Velocity Term Coefficient	0.1177
Velocity Squared Term Coefficient	0