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LEED v4 opt 2 Lighting Analysis Result Contradicts Itself?

Anonymous

LEED v4 opt 2 Lighting Analysis Result Contradicts Itself?

Anonymous
Not applicable

Please refer to my screenshot from my latest Lighting Analysis.

I'm really perplexed by the results because the comprising equinox results both show 91% passing, but the total is only 89%, granting only a single point instead of the 2 points that achieving over 90% would/should.

What is happening here?...

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scheerd
Alumni
Alumni
Accepted solution

There are two interpretations of this credit, and you can submit either one.

1. (the one we feel is intended) The percentage is the minimum area percentage meeting thresholds at either 9am or 3pm.

2. (the one that many users say GBC reviewers are using lately) The percentage is the area percentage that meets thresholds at both times.

#1 is easy to visualize and conceptualize, as it's a simple distribution of daylight at a point in time.

#2 is a little more complicated, because while a point may meet thresholds at one time, it may not at another time.  If it doesn't meet thresholds at BOTH times, it doesn't count at all.  In your case, you have a different 91% at 9am than at 3pm, and apparently at least 2% of the points meet thresholds at only one time and not the other.

I would suggest submitting results for just one of the times, though if you only need 1%, changing the material colors or small geometry changes should get you there for both hours as well.

David

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Anonymous
Not applicable

David,

Thanks for your prompt reply.

I looked again at the LEED ID+C Guidelines and saw that it's actually very explicit about submitting calculations for both 9am and 3pm... so I believe that I'm stuck trying to navigate the discrepancies with my results.

I'm not sure I understand why Insight "compares" the 9am and 3pm times against each other when they both pass at 91% on their own merits. I don't believe there's any language indicating an "overlap" requirement between the two times (and I'm not even clear on what exactly would be overlapping), so any input you have about the reason for this to help me understand would be appreciated.

Would I be able to perhaps submit two separate simulation results so that their numbers aren't distorted through Insight's weird comparison mechanism (if that's what's reducing my percentages)?

 

Thanks,

Eric

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scheerd
Alumni
Alumni

My interpretation has always been that 'both' means that the building meets 75%/90% area at 9am and also at 3pm, but it doesn't have to be the same parts of the building comprising that 75%/90%.  Rationally it makes sense that if daylighting leads to a lighting load reduction, then it doesn't matter where that load is, and design-wise, it's better actually that more of the building (ie different parts) get daylight at different times rather than dark places always being dark.

 

But we got quite a few GBC reviewers interpreting it that only the areas of the building that meet thresholds at both times could be counted.  That means that if an area meets at only one time, it doesn't count.  To me, this interpretation is totally wrong, but we need more submitters to submit our way and then appeal to have GBC adjust its ways.

 

David

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Anonymous
Not applicable

I was afraid that's what you meant, but I suppose on some level I just didn't want to believe it.

Do you believe that I would just be able to provide two separate simulation results so that Insight doesn't cross reference them by default? I'm not confident that submitting only one of the simulations would clear us of our documentation obligations. Have you seen this piecemeal approach attempted before?

-Eric

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scheerd
Alumni
Alumni

Last time I looked at the submittal form, it is a spreadsheet that has cells for only one result.  The way it's usually done is to enter the values for the worst time (9am or 3pm), or enter the 'both' results, from the Room Schedule.

David

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scheerd
Alumni
Alumni
Accepted solution

Important notes about changes to handling of glazing materials for Insight Lighting v4+ are available at the post below:

https://forums.autodesk.com/t5/lighting-solar-analysis-forum/critical-update-glazing-materials-for-l...

 

Insight version 4.031 is available here: 

When updating to this new version, be sure to check your Glazing materials per the post above 

https://insight360.autodesk.com/oneenergy/Landing/Download

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