[TRNSYS-users] Incident Angle Modifier - With only one value of longit IAM

[Edward Halawa]

Dear All,

I read Michael's explanation on how to create IAM matrix values for Type
71. See link below:
http://sel.me.wisc.edu/trnsys/mailinglist/archive2003/msg00021.html

My question is, how should I deal with IAMs data with only 1 IAM value
for longitudinal angle?

Suppose I have the following data:
Dir.      |0    | 20   | 40   | 60   | 90   |
Trans IAM | 1.0 | 1.1  | 1.3  | 1.4  | 0.00 |
Long. IAM |            | 0.85 |             |

Is the following reasonable:
0 20 40 60 90
40
0.85
0.94 (=1.1 * 0.85)
1.11 (=1.3 * 0.85)
1.19 (=1.4 * 0.85)
0

Or, should I assume the IAM values for other longitudinal angles ?

I appreciate your help.

ehalawa