# How would be create the sun-up-hours .txt from AnnualIrradiance

Dear @chris,

I need a Info.
I want to ask, how they are calculated the sun-up-hours, generated by the annual irradiance calculation in the text file.
I ask you, because by testing an original EPW file and one EPW created from external data for the same location, the sun-up-hours file, gives me exactly the same number (e.g. 4396), even if from the custom EPW, I know that the hours they have a value of ≥1 W/m² of direct radiation (not direct normal) are 3139 hours.

I believe the sun-up hours are efined as those where the sun is above the horizon and not according to radiation amount.
See this discussion, for example.
-A.

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Hey @LaFleur remember that the direct radiation can be zero for a cloudy hour but there’s still plenty of diffuse radiation.

@AbrahamYezioro 's answer is correct. We just use the location information (latitude and longitude) in the Wea/EPW file to build a Sunpath under the hood. Then, we use that to tell us which hours of the year the sun is physically above the horizon.

Thanks chris,
I want to make a comparison between how many hours of sun-beam are provided by the LB Sun Path component, and what is provided by the sun-up-hours text file for the same location and I have a interesting results.

• Out from the sun-up-hours.txt I have 4396 hours where the sun is above the horizon;
• Out from the LB SunPath, if I read all the hours with a altitude 0.1° I have 4460 hours where the sun is above the horizon. There are a gap of 64 hours.
• Out from the LB SunPath, if I read all the hours with a altitude 1.0° I have 4403 hours where the sun is above the horizon. There are a gap of 7 hours.

So the result tells us that the annual irradiance comp, calculates the hours in which the sun is ≥1°above the horizon.

comparison_sun-up-hours.gh (51.4 KB)

Thanks for all!!

Best regards

Hours in Wea files usually fall on the half-hour (eg. 10:30) but it looks like you are requesting HOYs from the LB Sunpath that fall on the hour (10:00). So make sure that you do this if you want alignment with the recipe. Also, you should use an altitude > 0 since this is what it used in the recipe

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