Hi all,
I’m looking for any suggestions about PAR analysis by ladybug tools. I have checked there was a similar topic last year. Here It seems there was no conclusion. I have also read lots of articles about conversion between solar radiation (w/m2) and PAR.
I’m wondering if there is anyone got experience in setting this kind of tool for PAR analysis. Any comments are appreciated.
Thanks,
Josh
Hi Josh,
We have encountered this a number of times in glasshouse designs and often there are different targets from the botanist, sometimes it is hours over a certain brightness, as could be calculated out of an annual illuminance simulation, or as a fraction of outdoor light availability, which may be as simple as a daylight factor calculation. If the botanist is happy with illuminance as a proxy for PAR, that can be worthwhile for designing around performance of low-light spaces that may not receive direct sun.
We generally let the Botanist calculate PAR via a preferred conversion method from that illuminance value (perhaps it is from local measurements), though I appreciate this does not take into account material reflectance of the non-visible PAR wavelengths (keeping it simple).
The language in agribusiness and plant conservatories is generally a daily light integral, which is simply the cumulative illuminance over a day, measured in lux-hours. This at least is a simple bit of post-processing out of an hourly simulation and can be built into a grasshopper workflow without much hassle.
Cheers!