[esp-r] Re: AIM-2 ACH question

[Ian Beausoleil-Morrison]

Lukas,

You have specified both an airtightness rating at 50 Pa depressurization as
well as an effective leakage area.  The model will use these two values to
determine the building's fabric leakage coefficient and the exponent of the
flow-versus-pressure relationship.  Refer to the subroutine AIM2_COandN in
the source file cetc/aim2_pretimestep.F to details on these calculations as
well as pointers to supporting documents that explain the model.

- Ian

Ian Beausoleil-Morrison, Ph.D.
Associate Professor and Canada Research Chair
Mechanical and Aerospace Engineering
Carleton University

1125 Colonel By Drive
Ottawa, Ontario, Canada
K1S 5B6

ibeausol at mae.carleton.ca
+1 (613) 520-2600 ext 3022 (telephone)
+1 (613) 520-5715 (facsimile)
www.mae.carleton.ca



_______________________________________________________________________
From: esp-r-bounces at lists.strath.ac.uk
[mailto:esp-r-bounces at lists.strath.ac.uk] On Behalf Of Lukas Swan (Dal)
Sent: April 23, 2008 16:57
To: esp-r at lists.strath.ac.uk
Subject: [esp-r] AIM-2 ACH question

Hello
I am working with the *.aim file variables and have found an unexpected
impact.
Using all the same values and only modifying the ACH50 results in the
opposite response I would expect.

Particularly- when I raise the ACH50 the annual zone (I only have 1 in the
model) infiltration air load energy drops.
As I raise the ACH50 further, it continues to decrease.
Three test cases:
ACH50   Annual Air Load(kWh)
1.5          -6557
3.5          -1754
5              -1045

Thoughts on why an increase in air changes per hour causes decreased energy
consumption?

Lukas Swan
Nova Scotia
Canada

#
# AIM-2 input file for CCHT house from HOT2000 inputs
#
#---Leakage
description-----------------------------------------------------------------
--------
#1  1.50  10  1  523       # blower door input; 1.5 ac/h @50Pa; ELA dP=10Pa;
1=ELA not given; ELA=523.7 cm^2.
#1  3.50  10  1  523
1 5 10 1 523
#                           # Set first number to 6 (and no other data) for
energy tight house
#---Leakage
distribution----------------------------------------------------------------
--------
1  0.20  0.65  0.15         # Use default leakage distribution.
#                           # Set `1  0.1 0.6 0.2' for user input leakage
distribution.
#---Shielding and terrain
data------------------------------------------------------------------
3 7 4 2 10.0                # See subroutine
/users/ian/src/esp-r/esrubld/aim2.F/AIM2_READIN
#---Height of building eaves
(m)----------------------------------------------------------------
2.7
#---Flue diameters
(mm)------------------------------------------------------------------------
-
0  0. 0. 0. 0. # furnace, fire#1, fire#2, dhw#1, dhw#2.
#---Zone
indices---------------------------------------------------------------------
-----------
1                  # Zone whose temperature used to calculate density of
indoor air.
1 1                # Total number of zones receiving infil; indices of zones
receive infil.
0                  # Index of basement zone (=0 if no basement).
#---------------------------------------------------------------------------
--------------------