The weather data is interpolated only if the time step is set to less than an hour, because the vast majority of weather files have hourly data. The interpolation is essentially linear, with weighting added to smooth the data. I don't know of any basis for the weighting or linear interpolation except for general principle of continuity. Even then, that doesn't really apply to parameters like wind speed and direction.
The effect on system simulations would be to reduce discontinuities due to the granularity of the hourly weather data. This issue does not apply to DOE-2 models, which uses only an hourly time step.
Joe
Joe Huang White Box Technologies, Inc. 346 Rheem Blvd., Suite 205A Moraga CA 94556 yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx http://weather.whiteboxtechnologies.com for simulation-ready weather data http://www.whiteboxtechnologies.com (o) (925)388-0265 (c) (510)928-2683 "building energy simulations at your fingertips"
On 8/5/2015 12:46 PM,
shadoworion57000@xxxxxxxxx [EnergyPlus_Support] wrote:
Hi,
The weather data is interpolated for each time step. I noticed that the interpolation isn't linear but that it is actually "weighted" (Weather Data Hourly Interpolation, in the I/O Reference Guide). I was wondering what's the basis for it?
It seems that, for example, the average outdoor air dry bulb temperature for an hour increases with the time step. Does this have an effect on the overall response of the systems modeled? Same question but when comparing an EnergyPlus model with a DOE-2 model?
Thank you for your input!
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Posted by: Joe Huang <yjhuang@xxxxxxxxxxxxxxxxxxxxxxxx>
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