This document provides an overview and demonstration of BREEZE Software's Downwash Analyst tool. It discusses: 1. The tool's ability to visualize building downwash effects and Building Profile Input Program (BPIP) calculations through different analysis modes. 2. How to launch the Downwash Analyst from BREEZE AERMOD or independently. 3. The four BPIP analysis modes - BPIP GEP, BPIP GEP Max, BPIP HWE, and BPIP Output - and how to use each mode to view different BPIP parameters for stacks. 4. Examples of how building characteristics like height, width, separation distance, and elevation influence BPIP calculations of Good Engineering

1. BREEZE Software
12770 Merit Drive | Suite 900 | Dallas, TX 75251
+1 (972) 661-8881 | breeze-software.com
BREEZE Downwash Analyst and
3D AERMOD Plumes Using
BREEZE AERMOD with 3D Analyst

2. Downwash Analyst

3. Downwash Analyst
Objectives:
1. General Introduction to BREEZE Downwash Analyst (DWA)
2. Demonstrate DWA’s BPIP Analysis Modes.
3. Demonstrate DWA’s PRIME Plume Mode.
4. Demonstrate how BREEZE AERMOD 6 and BREEZE 3D
Analyst can be used to display hourly AERMOD plumes.
5. Demonstrate, three dimensionally, how building profiles
influence AERMOD plumes.
BREEZE Downwash Analyst

4. Downwash Analyst
Objective #1
General Introduction to BREEZE Downwash Analyst
• History… DWA now
“removes the mystery
of BPIP”.
• Display PRIME plume
geometry.
• Downwash, BPIP, or
Building Profile
Analyst?
• Simple ‘visualization
tool’… nothing to enter
or edit… just observe.
• Understanding what
you see is the hard
part.

5. Downwash Analyst
What is BPIP? What does it do?
BPIP Does Two Things:
1. Computes the maximum Good Engineering Practice
(GEP) height for all stacks influence by one or more
buildings.
2. Computes the Building Profile Input Parameters (BPIPs)
for 36 wind directions around each stack.
What is BPIPPRM? What’s the difference?
BPIPPRM is the ‘PRIME’ version of BPIP that includes the X,Y
position of building profiles, relative to point sources (i.e. stacks).

6. Downwash Analyst
BPIP Acronyms….
BPIP – Build Profile Input Program
BPIPPRM – PRIME version of BPIP
PRIME – Plume Rise Model Enhancement (includes X,Y values)
GEP – Good Engineering Practice stack height
SIZ – Structure Influence Zone
L – min(W, H), minimum Width or Height of a SIZ
GEP SIZ – SIZ used to locate stacks for GEP calculations
HWE – Height of Wake Effect (same equation as GEP, larger SIZ)
HWE SIZ – SIZ used to locate stacks for HWE/BPIPs calculations
BPIPs – Building Profile Input Parameters

7. Downwash Analyst
How to launch BREEZE Downwash Analyst
1. From BREEZE AERMOD 6
a. Open project file.
b. Select ‘Downwash Analyst’ from
Tool Menu.
Note: If an .amz file exists and contains an Aermod.prm
file, the .prm file will also be loaded.
Note: This will load the stack and building geometry
contained in the AERMOD input file (i.e. the .ami
file).
2. From Downwash.exe
a. Open BREEZE .amz file
containing ‘Bpip Input File’ and/or
‘Aermod.prm’ file.
b. Open EPA BPIP files with .inp or
.bpi extension.
c. Open BREEZE .prm files.
Note: This will load the stack and building geometry
contained in the ‘Bpip Input File’ (i.e. the file
generated and saved to the .amz file when ‘BPIP
Model Run’ was last executed from within
BREEZE AERMOD 6.)

8. Downwash Analyst
BREEZE Downwash Analyst’s Layout

9. Downwash Analyst
Objective #2
Demonstrate BREEZE Downwash Analyst’s BPIP Analysis Modes.
5L 5L
1/2L
1/2L
2L

10. Downwash Analyst
DWA’s Four BPIP Analysis Modes:
Two Things… for Each of BPIP’s Two Things…
1. Compute the maximum GEP height for all stacks influenced by one
or more buildings.
1. BPIP GEP - Show the GEP (a measure of how much buildings influence
a stack) for all wind directions. Only stacks within a GEP SIZ will produce
a GEP value.
2. BPIP GEP Max - Show the single wind direction and corresponding
tier(s) that have the maximum influence on a stack.
2. Compute the Building Profile Input Parameters (BPIPs) for 36 wind
directions around each stack.
3. BPIP HWE - Show how stacks are located within the HWE SIZ of
buildings for each wind direction.
4. BPIP Output - Show the final BPIPs for each wind direction.

11. Downwash Analyst
1. BPIP GEP - Select Stack & Wind Direction - Display the single-tier or tier-group,
with it's GEP-SIZ, that produces the maximum GEP stack height for a selected stack and
a selected wind direction.
2. BPIP GEP Max - Select Stack - Display the single-tier or tier-group, with it's GEP-
SIZ, and the single wind direction that produces the maximum GEP height for a selected
stack.
3. BPIP HWE - Select Stack & Wind Direction - Displays the single-tier or tier-
group, with it's HWE-SIZ, that produces the maximum HWE for a selected stack and a
selected wind direction.
4. BPIP Output - Select Stack & Wind Direction - Display the single-tier or tier-
group that produces the maximum HWE and it's corresponding BPIPs (i.e. Building Profile
Input Parameters including height, width, length, and X,Y offsets) for a selected stack and
a selected wind direction.
BPIP Analysis Modes

12. Downwash Analyst
DWA – Analysis Mode #1
BPIP GEP - Select Stack & Wind Direction

13. Downwash Analyst
BPIP GEP - Select Stack & Wind Direction
Display the single-tier or tier-group, with it's GEP-SIZ, that produces the
maximum GEP stack height for a selected stack and a selected wind direction.

14. Downwash Analyst
GEP Calculation for Selected Stack and Selected Wind Direction
Wp
Hcht
GEP SIZ
GEP for
selected wind
direction
Max GEP for selected
stack (produced from
other wind direction)
1.5L
GEP = Good Engineering Practice stack height
Eft = Elevation of Focal Tier
Es = Elevation of Stack
Hcht = Height of Common Height Tier
Wp = Projected Width of single tier or tier group
L = min(Wp, Hcht)
Tier Group
GEP =(Eft – Es) + Hcht + min(Wp, Hcht) x 1.5
Focal Tier and
Common Height
Tier
5L

15. Downwash Analyst
Squat Tier
W = 15, L = 15, H = 5
GEP = H x 2.5
Cube Tier
W = 10, L = 10, H = 10
GEP = H x 2.5
GEP for Squat and Cube Tiers….
GEP =(Eft – Es) + Hcht + min(Wp, Hcht) x 1.5

16. Downwash Analyst
GEP for Tall Tiers….
GEP =(Eft – Es) + Hcht + min(Wp, Hcht) x 1.5
Tall Tier
W = 5, L = 5, H = 10
GEP = H + (Wp x 1.5)

17. Downwash Analyst
GEP for Tall-Long Tiers….
GEP =(Eft – Es) + Hcht + min(Wp, Hcht) x 1.5
Tall-Long Tier
W = 5, L = 10, H = 10
GEP = H + (Wp x 1.5) or GEP = H x 2.5

18. Downwash Analyst
Tall Round Tier
D = 5, H = 10
GEP = H + (D x 1.5)
GEP for Round Tiers….
GEP =(Eft – Es) + Hcht + min(Wp, Hcht) x 1.5
Squat Round Tier
D = 10, H = 10
GEP = H x 2.5

19. Downwash Analyst
Two Tiers
W = 5, L = 5, H = 10
Separation = 6GEP = 0 GEP = H + (Wp x 1.5)
Blue SIZ when
produced by single
tier.
GEP for Tier Groups… The Complex Part of BPIP
GEP = H x 2.5
Yellow SIZ when produced
by tier group.
Tiers can combine when
the projected width of
both tiers is greater than
the minimum distance
between the tiers.

20. Downwash Analyst
Two Tiers
W = 5, L = 5, H = 10
Separation = 8
Two tiers with minimum separation distance greater than either
tiers maximum projected width will never be combined….
GEP = H + (Wp x 1.5)

21. Downwash Analyst
Two Tiers
W1 = 5, L1 = 5, H1 = 7.5
W2 = 5, L2 = 5, H2 = 10
Separation = 6
GEP = 7.5 + (5.5 x 1.5) = 15.75
GEP = 7.5 + (7.5 x 1.5) = 18.75
GEP = 10 + (7.0 x 1.5) = 20.5
GEP = 0
Group has
larger GEP
Single tier has
larger GEP
Wp < Separation
Stack not in
GEP SIZ
Two tiers with different heights….

22. Downwash Analyst
Three Tiers
W1 = 4, L1 = 4, H1 = 4
W2 = 4, L2 = 4, H2 = 5
W3 = 4, L3 = 4, H3 = 6
Separation = 1
Three medium-height tiers with different heights….
GEP = 6 + (4.5 x 1.5) = 12.75
Single tier has
larger GEP
GEP = 5 + (5.0 x 1.5) = 12.5
GEP = 4 + (4 x 1.5) = 10
Not in GEP Siz
of shortest tier
GEP = 4 + (4 x 1.5) = 10
Group does not
produce larger GEP
Group has
larger GEP

23. Downwash Analyst
GEP = 7 + (7 x 1.5) = 17.5
Three tall tiers with different heights….
Three Tiers
W1 = 2, L1 = 2, H1 = 7
W2 = 2, L2 = 2, H2 = 8
W3 = 2, L3 = 2, H3 = 9
Separation = 1
All other group tiers (yellow)
Focal tier (blue)
Common height tier (orange)

24. Downwash Analyst
Three Tiers
W1 = 2, L1 = 2, H1 = 7
W2 = 2, L2 = 2, H2 = 10
W3 = 2, L3 = 2, H3 = 11
Separation = 1
GEP = 7 + (7 x 1.5) = 17.5
Two of the three tiers taller….
GEP = 10 + (5.5 x 1.5) = 18.25
DWA can toggle between 3D view
and top-down view.

25. Downwash Analyst
Three Tiers
W1 = 2, L1 = 2, H1 = 7, E1 = 2
W2 = 2, L2 = 2, H2 = 10, E2 = 0
W3 = 2, L3 = 2, H3 = 11, E3 = 0
BPIP assumes that all
tiers in a group have the
same elevation as the
focal tier.
GEP = 7 + (7 x 1.5) = 17.5
DWA shows this effect by moving the
base of all tiers in a group to the
focal tiers elevation.
GEP = 10 + (5.5 x 1.5) = 18.25
Varying Tier Elevations… what does BPIP do?

26. Downwash Analyst
GEP = 10 + (5.5 x 1.5) = 18.25
Varying Tier Elevations… what does BPIP do?
Three Tiers
W1 = 2, L1 = 2, H1 = 7, E1 = 0
W2 = 2, L2 = 2, H2 = 10, E2 = 0
W3 = 2, L3 = 2, H3 = 11, E3 = 0
Three Tiers
W1 = 2, L1 = 2, H1 = 7, E1 = 0
W2 = 2, L2 = 2, H2 = 10, E2 = 0
W3 = 2, L3 = 2, H3 = 5, E3 = 6
GEP = 11 + (5.5 x 1.5) = 19.25

27. Downwash Analyst
Three Overlapping Tiers
W1 = 8, L1 = 2, H1 = 7
W2 = 5, L2 = 2, H2 = 10
W3 = 2, L3 = 2, H3 = 11
Separation = 1
Overlapping Tiers? Are they allowed?
GEP = 10 + (5.5 x 1.5) = 18.25GEP = 7 + (7 x 1.5) = 17.5 GEP = 10 + (5 x 1.5) = 17.5

28. Downwash Analyst
Stacked tiers? An obvious mistake…
GEP = 4 + (4 x 1.5) = 17.5
Three Stacked Tiers
W1 = 8, L1 = 2, H1 = 7, E1 = 0
W2 = 5, L2 = 2, H2 = 3, E2 = 3
W3 = 2, L3 = 2, H3 = 1, E3 = 1
Tier elevations should
always be ground level…
never the roof-top
elevation of another tier.
GEP = 7 + (7 x 1.5) = 17.5

29. Downwash Analyst
Multi-Tier Buildings… prevent tier grouping…
EPA Example A5ST - Three multi-tier
buildings containing three tiers each.
What does this accomplish?
1. Changes the BPIPs? YES…
but why?
2. Prevents stacked tiers (i.e. a
single elevation value is
assigned to all tiers in a multi-
tier building).
No other tiers in the building
containing the Focal Tier will be
part of a Tier Group.

30. Downwash Analyst
Stack elevation… how does it affect GEP?
Stack elevation will shift the GEP values. However, the relative elevation
of a stack to tiers will not affect tier associations to the stack. Only
changes relative tier-to-tier elevations will affect the association of tiers to
stacks.

31. Downwash Analyst
DWA – Analysis Mode #2
BPIP GEP Max - Select Stack

32. Downwash Analyst
BPIP GEP Max - Select Stack
Display the single-tier or tier-group, with it's GEP-SIZ, and the single wind
direction that produces the maximum GEP height for a selected stack.

33. Downwash Analyst
BPIP GEP Max - Select Stack
Select a stack to see the wind direction and single-tier or tier-group that
most influences (i.e. produces the highest GEP for) the stack.
BPIP locates
all stacks within
GEP SIZs and
computes a
GEP value for
1440 (360 x 4)
wind directions
around each
stack.

34. Downwash Analyst
DWA – Analysis Mode #3
BPIP HWE - Select Stack & Wind Direction

35. Downwash Analyst
BPIP HWE - Select Stack & Wind Direction
Displays the single-tier or tier-group, with it's HWE-SIZ, that produces
the maximum HWE for a selected stack and a selected wind direction.

36. Downwash Analyst
HWE Calculation for Selected Stack and Selected Wind Direction
HWE =(Eft – Es) + Hcht + min(Wp, Hcht) x 1.5
HWE = Height of wake effect
Eft = Elevation of Focal Tier
Es = Elevation of Stack
Hcht = Height of Common Height Tier
Wp = Projected Width (single tier or tier group)
L = min(Wp, Hcht)
5L
1/2L
1/2L
2L
Wp
Hcht
HWE SIZ
5L
HWE for
selected wind
direction
1.5L
Tier Group
Common
Height
Tier
Focal
Tier

37. Downwash Analyst
DWA –Analysis Mode #4
BPIP Output - Select Stack & Wind Direction

38. Downwash Analyst
BPIP Output - Select Stack & Wind Direction
Display the single-tier or tier-group that produces the maximum HWE and it's
corresponding BPIPs (i.e. Building Profile Input Parameters including height, width,
length, and X,Y offsets) for a selected stack and a selected wind direction.

39. Downwash Analyst
Wind Dir = 210
Wind Dir = 200
Wind Dir = 190
Wind Dir = 180
Wind Dir = 170
Wind Dir = 160
Wind Dir = 150
BPIPs for 36 Wind Directions Around a Stack… produced by
either a Single-Tier or a Tier Group…

40. Downwash Analyst
BPIPs do NOT have an elevation… the projected height is
relative to the stack elevation…
All stacks and tiers are moved to zero elevation in ‘BPIP Output’ Mode

41. Downwash Analyst
Pick a stack
and rotate the
wind direction
to view all the
BPIPs.
BPIP Output - Select Stack & Wind Direction

42. Downwash Analyst
DWA –Analysis Mode #5
PRM Plume - Select Stack
3D Display
Objective #3

43. Downwash Analyst
DWA –Analysis Mode #5
PRM Plume - Select Stack
Side-View Chart

44. Downwash Analyst
Select ‘Downwash plume centerline file’ in the BREEZE
AERMOD 6 Output / Options dialog….

45. Downwash Analyst
Variation of PRIME plume and near/far wake boundaries
with increasing wind speed…
1.5 m/s
2.5 m/s
3.5 m/s
4.5 m/s

46. Downwash Analyst
Variation of PRIME plume and near/far wake boundaries
with varying wind direction…
Wind Dir = 70
Wind Dir = 80 Wind Dir = 110
Wind Dir = 100

47. AERMOD 6 with 3D Analyst
Demonstrate how BREEZE AERMOD and BREEZE 3D
Analyst can be used to display 3D plumes.
Objective #4

48. Select ‘1 hr’ post file from the Output / Post Files dialog…
A 2km x 2km x 200m grid
with 50m XY spacing and
10m Z spacing
AERMOD 6 with 3D Analyst

49. Select ‘1 hr’ post file from the Output / Post Files dialog…
AERMOD 6 with 3D Analyst

50. Load the post file into BREEZE 3D Analyst…
Select a time and display
Volume rendering with XY,
XZ, YZ contour planes
Turn off the bounding box,
reduce the contour’s
FillOpacity, and reduce
ElevationScale
Set the Volume properties
as shown above… see
User’s Guide for details
about each setting
AERMOD 6 with 3D Analyst

51. Select an appropriate set of ‘User Defined’ levels…
AERMOD 6 with 3D Analyst

52. Save all 3D window settings using the File / Templates /
Load & Save options….
AERMOD 6 with 3D Analyst

53. First look at the plume of a single stack with no buildings
and increasing wind speed in one direction…
AERMOD 6 with 3D Analyst

54. 0.5 m/s
1.0 m/s
1.5 m/s
2.0 m/s
4.0 m/s
8.0 m/s
12.0 m/s
16.0 m/s
AERMOD 6 with 3D Analyst

55. Demonstrate how building profiles influence AERMOD plumes.
Objective #5
Without Building
Squat Building
Tall Building
AERMOD 6 with 3D Analyst

56. With Building
30x30x15mWithout
Building
1.0 m/s
1.5 m/s
2.0 m/s
AERMOD 6 with 3D Analyst

57. 16.0 m/s
12.0 m/s
8.0 m/s
4.0 m/s
AERMOD 6 with 3D Analyst

58. Without
Building
1.0 m/s
1.5 m/s
2.0 m/s
With Building
30x30x30m
AERMOD 6 with 3D Analyst

59. 16.0 m/s
12.0 m/s
8.0 m/s
4.0 m/s
AERMOD 6 with 3D Analyst

60. Use 3D Analyst’s Tools / Merge Data / Difference to compute
the 3D difference of a plume with and without a building…
AERMOD 6 with 3D Analyst

61. 1.0 m/s
2.0 m/s
3.0 m/s
4.0 m/s
5.0 m/s
6.0 m/s
8.0 m/s
12.0 m/s
Plume with Building – Plume without Building =
AERMOD 6 with 3D Analyst

62. Downwash Analyst, AERMOD 6, 3D Analyst
Conclusions…
1. BREEZE Downwash Analyst provides a means to examine the
interactions between buildings and stacks.
2. DWA provides a detailed display of how BPIP computes GEP
values and BPIPs for each stack.
3. DWA provides a quick easy way to determine the conditions that
produce the maximum GEP for a stack.
4. DWA provides a quick easy way to inspect and verify building
models.
5. DWA provides a means to view the BPIPs and their associated
tiers for each stack.
6. AERMOD plumes can be examined three dimensionally using
BREEZE AERMOD 6’s 3D Receptor Grids and BREEZE 3D
Analyst’s Volume Rendering functions.