Energy plus weather files UTC/GMT

energyplus
weather-file
retag add tags

i have data from a weather station (2014, 2015) and i want to transform them to epw files. The first temperature of the epw file (from 8760) is the average temperature from 00:00-01:00 (e.g. 2014 of my data) or the exact temperature of 00:00 (end 2013-2014)? The solar track is something that the software calculates from the epw file or something that you set additionally (e.g. UCT+1) Is it possible to create epw file without solar tracks. For example in elements software (bigladder) there are many columns that i do not know (cosine, zenith etc.). Is it a good idea to use an existent epw for a city and just copy paste these columns or is it possible to leave them empty.

155

Theo

asked 2016-08-02 01:10:36 -0500, updated 2016-08-05 20:16:14 -0500

edit flag offensive 0 remove flag close merge delete

Comments

add a comment see more comments

Hello, i use EnergyPlus with .epw files and run my simulations with daylight saving time, my answers are in the same order that your questions:

1.If your .epw are a typical year (a theorical year of 5 or more years), in each hour of each day the values will be a representative average of the years that conform the typical year. If your .epw are a test reference year, the values of each hour concern only for a specific year choosing for the simulation.

2.The .epw has a format and structure concerning only for the specific values of the climatological variable contained, the daylight saving period is configured in your simulation software.

3.The .epw has in its structure the data of latitude and longitude, but in addition you have to put this values in your simulation software and it calculates the solar position and shadows during the simulation process.

Hope this info help you, Greetings community!

Hello Again, thanks for specify your doubts. The first temperature of the new .epw file have to be an average exterior temperature (mean air temperature) from 00:00-01:00, because the average temperature value will be representative from the first hour, then the next average hour value will be the representative of the second hour and successively
The simulation program calculates the solar track (hourly use + or - hours from GMT) using solar geometry. This is possible because the particular geographical ubication values latitude, longitude, and high above sea specified in the .epw data.
Because you will use an .epw and a part of its essential data in the structure is its geographical ubication, its not possible to work without solar track, consequently each point on the planet have an solar and specified track.
The hip, sin, cos, zenith, etc. are values that the program needs to calculate solar trayectory based in solar geometry, this data are very important for the simulation, and each city has specified values, again it depends of your point in the planet for work the simulation.

What simulation program will use? for which city will do the simulation?

Greetings community!

354

blucu

answered 2016-08-02 09:08:55 -0500, updated 2016-08-07 13:24:34 -0500

edit flag offensive 0 remove flag delete link

Comments

I use DB and i do simulations for Copenhagen (UTC +1 and +2 in the summer). I thought to take an old epw file and change only the weather data (T RH etc.). The solar track of epw referred on "clock local time" (without - +1 winter-summer time) or solar time? the first value is based on average track at 00-01:00? My problem is how to combine correct weather data with correct solar track based on common time reference (refer to same hour). thanks

Theo (2016-08-08 07:29:41 -0500) edit

hi,for the .epw you will need do the conversion of solar time because the acquired data in the meteorological stations works with the format Z hour (GMT time). Then you have to convert this hour to your local time to know which values belongs to each hour, this work can be tedious and start is difficulty. Firstly,i suggest to configure a .xls template to make the conversion. For your location, the first climatological values for the first local hour in the customized .epw will be the hour Z values after the begin of the year of study