EPW (EnergyPlus Weather)
An EPW file is an EnergyPlus Weather file: a comma-separated text file of timestamped weather records. ArchiWind reads only the timestamp, wind direction and wind speed of each record, and computes wind statistics per month, per season and for the whole year.
File structure
- Plain text, comma-separated.
- File extension
.epwor.EPW, maximum 10 MB. - Line endings: CRLF (Windows) or LF.
- The first 8 lines are the standard EPW header (
LOCATION,DESIGN CONDITIONS, …,DATA PERIODS). They are skipped and not checked. - Every line after the header is one data record. Blank lines are not allowed.
- At most 10,000 data records.
There are typically 8760 lines for a full year.
Fields read
Each record must have at least 22 comma-separated fields. All other fields are ignored.
| Field | Name | Unit | Allowed values |
|---|---|---|---|
| 1 | Year | Integer | |
| 2 | Month | 1–12 | |
| 3 | Day | Valid day of that month | |
| 4 | Hour | 1–24 (hour 1 is 00:00–01:00) | |
| 5 | Minute | Integer, read modulo 60 (0 and 60 are the same) | |
| 21 | Wind direction, clockwise from north, direction the wind blows from | degrees | Number |
| 22 | Wind speed | m/s | Number |
How the data is used
- Records are sorted by timestamp, so their order in the file does not matter.
- Records can span several years, for example a multi-year history.
- Records are assumed to be hourly: each month’s coverage is its record count divided by 24.
- Speeds are taken to be measured at the Meteorological data recorded height you enter with the upload (1–300 m). The optional Roughness length (0–0.7 m, lower than that height) describes the terrain at the recording location.
- After uploading, ArchiWind shows a preview of the first and last records, sorted by time, with their wind speed and direction.
Rejected files
A file is rejected on upload if:
- any record has fewer than 22 fields, or a field above is empty or not a number;
- any timestamp is not a valid date and time (for example hour
0or day31in April); - it has more than 10,000 data records;
- any of the 12 months has no records;
- any month has less than 20 days of data (fewer than 480 hourly records).