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Re: [EnergyPlus_Support] diffuse solar

solar data is interpolated to the half/hour.  i will write that up for that section for the next release.

It may already be written up somewhere else in the documentation.  There are 87 instances of the word interpolation in 4 documents.

At 08:47 AM 2/1/2010, Hu,Jia wrote:

Thanks, Linda,
This rule is true for some variables, such as dry bulb temperature. For timestep frequencey report, the "hourly  value" reported matches with hourly value in weather file. and the timestep value is the interpolation of the hourly value using that formula.
But for some other outside variables, such as diffuse solar, it does not follow this formula. In timestep frequency report, the "half-hour value" (e.g. 8:30; 9:30) reported matches with hourly value in weather file.

On Mon, Feb 1, 2010 at 10:27 AM, Linda Lawrie <linda@xxxxxxxxxxxxxx> wrote:

Read about weather data interpolation in the IORef.

Page 1947 (PDF page 94)

At 06:06 PM 1/31/2010, Hu,Jia wrote:
In EnergyPlus, when timestep = 4, the diffuse solar in weather file is different from the output at the same hour. For example, in weather file, at 9:00, the diffuse solar is 58, while in the output, 58 appears at 8:30. This rule seems different from interpolation mentioned in help ref.
In calculating Daylight Factor, EP ref. mentions it uses hourly DF and then  interpolate the two hour DF to calculate the DF at time step in  one hour. So when calculating Daylight Factor, the Energyplus adopts which hour values of Diffuse and direct Radiation in the Outputfile?  Does EP use 58 (at 8:30 in the output), or use value at 8:00 in output (average values at 7:30 and 8:30, which are corresponding to 8: 00 and 9:00 in the weather file respectively) ? .


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