ladybug-tools/honeybee-legacy

Wind speed and direction calculation in DDY calculation

hongyuanjia opened this issue · 0 comments

Thanks for this great plugin!

I am trying to manually calculate DDY data using EPW files. And I found createDdyFromEPW being quite useful. I got a little bit confused by how the wind speed and direction calculation.

coldStdDevTemp = sortedDB[1384]
hotStdDevTemp = sortedDB[-1385]
winSpBelowTemp = []
windDirBelowTemp = []
winSpAboveTemp = []
windDirAboveTemp = []
for i, tem in enumerate(dbTemp):
if tem < coldStdDevTemp:
winSpBelowTemp.append(windSpeed[i])
windDirBelowTemp.append(windDir[i])
elif tem > hotStdDevTemp:
winSpAboveTemp.append(windSpeed[i])
windDirAboveTemp.append(windDir[i])
winSpBelowTemp.sort()
coldMonWind = winSpBelowTemp[922]
coldMonWinDir = int(sum(windDirBelowTemp)/len(windDirBelowTemp))
maxWind = winSpBelowTemp[-5] # Design Condition 3
winSpAboveTemp.sort()
hotMonWind = winSpAboveTemp[922]
hotMonWinDir = int(sum(windDirAboveTemp)/len(windDirAboveTemp))

In createDdyFromEPW, coldStdDevTemp and hotStdDevTemp was selected as the 18.5% (1385/8760) of dry-bulb temperature. I did not find any reference on this selection in ASHRAE HOF. Also failed to find any reference why coldMonWind was selected as the 923 of winSpBelowTemp. It would be great if you could provide some insights into this. Thanks!