Peak Irradiance values LBT 1.4.1

grasshopper honeybee
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#1

Hi all!

I want to understand a bit more how the peak irradiance works with the HB Annual irradiance recipe.
I want to understand if the values that are then displayed on the heatmap are:

  1. all occurring on the same day (which would potentially be the cooling design day)
  2. the peak value for each point throughout the whole year, meaning that they could potentially happen at different timesteps

I think the way this should work is 1), but I have the feeling that the way it actually works is 2)

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Looking at this picture for instance, I would expect the blue-ish portion to be deeper. The only way I could explain that limited effect of the lower spandrel on the peak irradiance values, is that actually the sun vector hitting each point is corresponding to the sun being in different positions in the sky, so that every time the peak value is obtained (which would be incorrect).

Let me know if this is clear! Thanks

#2

I have just displayed the peak irradiance according to 1) (by recording all the values of solar irradiance on the floor plate and searching for the maximum) and this is what I have obtained.

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Which happens to be at 3pm on 16 April which makes sense for a West facing shoebox

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#3

Hi @emilianoadam.cerutti ,

You are correct that it is number 2. The value is just the peak that each sensor experiences over the whole period of the Wea that you input.

You’ll see that you can get the other one with a little bit of data processing but option number 2 is also useful. If you want a streamlined workflow for option 1, I can add a coincident_ option to the HB Annual Peak Loads component that returns the conditions of the coincident peak of each sensor grid over time.

#4

Hi @chris, thank you for clarifying this.
I agree with you that option 2 is useful too, but I reckon 1 should be included as well as it’s more realistic.
I’ve been working for quite a while on overheating prediction strategies and a set of guidelines from the Australia Green Builidng Council suggests measuring the peak irradiance on the floor plate and make sure the floor-average peak irradiance (on the cooling design hour) is below a certain threshold.

For this reason I think it’d be great to have, as you said, a coincident_ option.

Thank you

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