Honeybee Intermezzo 8: Checking the quality of the EPW file
It is very important to make sure that the EPW file we are using is of good quality and does not miss any data. Providing wrong or inaccurate input data to a simulation leads to wrong or inaccurate – hence useless – results.
Create the plots
To check the quality, you should make plots of the data regarding the direct, diffuse and global radiation that exist inside the EPW file.
1. Create a Ladybug » Visualize Data » LB Hourly Plot component.
2. Connect the ‘direct_normal_rad’, ‘diffuse_horizontal_rad’, ‘global_horizontal_rad’ results from the LB Import EPW file component to the ‘data’ input of the LB Hourly plot.
3. Click on the LB Hourly Plot component and then go back to Rhino window. You should be able to see the corresponding graphs created.
Compare & make an evaluation
Firstly, you should check if there are significant data missing on the plot throughout the year time.
Afterwards, you can assess the values that you get through cross-checking of the same type of data retrieved from different sources.
For example, you can find maps of Direct Normal Irradiation from https://solargis.com/maps-and-gis-data/download and compare the expected irradiation value for the location of interest with the result that you get from the LB Hourly Plot.
Important to note: Keep in mind that extra-terrestrial irradiance is equal to 1367 W/m2 and it is extremely rare that the Direct Normal Irradiance measured at ground level exceeds this value. Even more so for Global and Diffuse Horizontal Irradiances.