Honeybee script for DLI photosynthesis lighting analysis

Hi Folks -

I’m still a newbie when it comes to ladybug/honeybee tools.

I was wonder if within any of the honeybee components, there is a lighting analysis for photosynthesis. I’m seeing this most commonly done in Day Light Integral (DLI). It seems looking at lux alone is not as beneficial.

If this is not a prebaked analysis, has anyone created a custom script that I could take a look at?

There’s no consensus or “gold standard” for what counts as a suitable Photosynthetically Active Radiation (PAR) analysis but people use a range of metrics to figure out if a certain plant can grow in a certain location. Listing off these metrics in order of least to most detailed:

  • Direct Sun Hours - the most basic study that just checks the amount of time that a plant will be in direct sun
  • Annual Irradiance - a bit more detailed than direct sun hours because you’re looking at solar energy and accounting for diffuse and reflected solar energy
  • Annual Daylight - a bit more detailed than annual irradiance because you’re looking at the solar energy in the visible part of the spectrum, which is also the part of the solar spectrum where chlorophyll is active. You’ll just have to pick illuminance thresholds that are meaningful for the plant you are trying to study.
  • Custom post-processed Annual Daylight - If you really wanted to be precise, you can postprocess the hourly illuminance values of annual daylight results to only look at the red and blue channels, which correspond to the range of Chlorophyll a and b respectively. Granted, the extra accuracy of this type of study won’t have any tangible effect if all of the materials in the scene are greyscale.

Hi @chris, thanks for the response. And I appreciate the extra detail and information per each analysis type.

I understand that there isn’t a slam dunk analysis to run.

I’ve seen some Day Light Integral (DLI) results presented on what looked like a honeybee backbone. Based on your information above, it sounds like that was likely a custom post-processed analysis.

It looks like its possible to use time data and lux data to possibly convert to DLI (mol per m2 per day).

Again, just curious what others are seeing/doing.

Thanks again,

Hi @scottfarbman,

There are conversion constants by Ian Ashdown that you may convert available hourly illuminace into PAR and then sum them up daily to estimate DLI. But it works only if you are concerning for daylight; any combination of daylight and light sources (esp. narrow band LEDs) are comming along errors. Here is a tool aiplantcare developed by my friend and me which works based on DC method and calculates DLI and more :slight_smile:


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Hi Fazel -
Thanks for the reply and shared info!
The specific study I’m looking to run is specifically for daylight only, so looks like I may be in luck with the “simple conversions”.

Much appreciated!

@chris seems like a basic question but is there anyway to give the average annual illuminance in LUX for outdoor terraces? and not percentages as in the case with UDI

Yes. Just use the HB Annual Results to Data component to bring in the hourly illuminance values as data collections and then you can analyze the data collections from there using various Ladybug components.