LEED V4 Daylight Option-2

leed
daylight
#1

Hello All,

Following is from LEED V4 EQ - Daylight Credit.


I just want to make sure that currently, there’s no ALREADY IMPLEMENTED way to average the direct and diffuse components for the illuminance analysis.

Thank You!

#2

Hi Devang, you can isolate direct and diffuse components in HB[+]. I havent checked up on the gh files from HB[+] in the last seven months or so, however, I am pretty sure that there is an example created by @mostapha that is somewhere on github or this forum.

Sarith

#3

Hi @sarith,

The way I understand it, they’re asking to find a day with the clearest sky withing 15 days of September 21st and a day with the clearest sky withing 15 days of March 21st and then take average of direct and diffuse component for those both days. I assume, a new skyfile needs to be generated based on these average values. Please correct me if I mis-interpreted this.

1 Like
#4

Hi Devang, you are right. I only paid attention to the last part of your post. This would be pretty useful to have in case it is not implemented in HB. I am not sure if we implemented this in HB[+] (at least I did not).
If you are planning to write the script for this for HB-legacy, I would suggest writing with minimal dependencies so that you can also send a PR for HB[+].
The paper that describes the all-weather sky model contains the formulae to calculate Sky clearness, which you could use to rank the “clarity” of skies. Let me know by email/inbox if you need any of the scientific articles for more info this.

Sarith

#5

Thank you @sarith for your comments and resources. I do plan to implement this. I have not come across any example file that does this. I will still wait for @mostapha to respond before I make a move.

#6

I am not sure if we implemented this in HB[+] (at least I did not).

Well, Mr. Honeybee did… https://github.com/ladybug-tools/honeybee/blob/master/honeybee/radiance/sky/gendaylit.py#L267-L281

Probably its easier to expose this than do a rewrite. We were having issues with gendaylit while creating matrices so @mostapha did a rewrite of gendaylit in Python.

#7

Hi @Mathiassn,
I saw that you asked the question on the Diva forum. Have you been able to come up with a workflow?

#8

@devang, Can’t you just use gendaylit to calculate this? Not sure what is going on with separating sun and sky or do they mean both should be included?

#9

@mostapha,
On Honeybee_Custom Sky component, shouldn’t the unit of _directNrmRad and _diffuseHorRad be w/m2? These values are for one hour only.

1 Like
#10

yes. W/mˆ2 is correct.

#11

Thanks for confirming. With this component, the LEED V4 Daylight Option-2 can be simulated in HB[Legacy].

#12

Hi devang.

I’m also trying to simulate the LEED V4 Daylight Option-2. But under the further explanation section its mentioned that you have to prepare the model to input custom values for average Direct Horizontal and average diffuse horizontal. Right now the Custom Sky component only accept direct Normal Rad. Am I right? I fail to see how I can input the values of the average Direct Horizontal into the direct Normal Rad.

Thank you in advance for your help

#13

Hi Claudio,

Sorry for getting back late. Yes, the LEED guide does ask for direct horiontal and the custom sky component takes direct normal radiation. I have used this route for several projects and I used the average of direct normal radiation. Please also read this discussion and especially the part where Anna shares the opinion of one of the LEED expert.

#14

Thanks Devang,
That clarify my question.

Cheers