v4 SSc6 - Hardscape requires a minimum of 0.2 fc to be counted

Thanks Bill, good to know. I can see where they are coming from, and you too, but seems like they should issue an addenda with this immediately. To change interpretation mid-stream without notice is not fair.

Bill,

Thanks for reaching out to us in regards to this.
Per ASHRAE 90.1 and LEED requirements, tradable exterior lighting surfaces must be designed to be illuminated in order to be counted in the Baseline exterior lighting power allowance:

For LEED v4 EA Prerequisite: Minimum Energy Performance submittals, ASHRAE 90.1-2010, Section states: “The total exterior lighting power allowance for all exterior building applications is the sum of the base site allowance plus the individual allowances for areas that are designed to be illuminated and are permitted in Table 9.4.3B for the applicable lighting zone."

Similarly for LEED 2009 EA Prerequisite: Minimum Energy Performance submittals, the ASHRAE 90.1-2007 User’s Manual, Section 9.4.5 – Determining Exterior Building Lighting Power Compliance, indicates that the exterior lighting power allowance (ELPA) “is calculated by multiplying each lighted area or width of door opening by the appropriate exterior lighting unit power allowance.”

However, if the LEED ASHRAE 90.1 Exterior Lighting Power documentation confirms that each surface where the exterior lighting power allowance is applied is “designed to be illuminated” or “lighted”, there is no defined minimum threshold that the project must adhere to in order to be counted in the Baseline lighting power allowance. A minimum 0.2 footcandle requirement does not apply.

Note that the IESNA Lighting Handbook recommends a minimum horizontal illuminance level of 0.2 footcandles for basic parking lot lighting applications. To support the claim that the surface is “designed to be illuminated”, a project team may optionally reference these IESNA values. However, this minimum footcandle level is a recommendation only, and is not stipulated by ASHRAE 90.1. Other justification supporting the claim that the surface is “designed to be illuminated” will also be accepted.

We are following up with you offline to ensure this reference to a “0.20 footcandle” requirement is corrected for your project.

Best,
MRS

I agree that the 0.2 fc is not a definite requirement. But it begs the question about what is considered designed to be illuminated? Any amount of lighting no matter how small? What if I take my photometrics to 0.00000000000001 fc, it that illumination? I checked 90.1-2016 to see if this has been addressed yet and could not find anything. It seems to me that it would be useful to submit an ASHRAE 90.1 interpretation to ask this question and get some definitive answer. Right now USGBC is leaving this wide open to interpretation by individual projects.

It is clearly wrong, and always has been, to claim energy savings for surfaces that are not adequately illuminated. That is like adding building area to the baseline and heating/cooling it as a means to claim additional savings. It is simply not a reasonable or fair comparison.

Thanks Marcus Sheffer for the recommendation to pursue an ASHRAE Interpretation on this issue. ASHRAE Interpretation 90.1-2010-33 clarifies this topic:

https://www.ashrae.org/File%20Library/docLib/StdsInterpretations/IC-90.1...
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Interpretation 1: The qualifier “…designed to be illuminated…” does not specify lighting design criteria. However, it was the intent of the Standard that spaces, areas, or applications that claim Lighting Power Density for compliance or performance rating have been designed to some reasonable lighting design criteria that meets industry standards, good design practice, and client desires.

This interpretation also applies to the 2013 and 2016 versions of Standard 90.1.

Interpretation No.2: For tradable surfaces, only the area that is designed to be illuminated may be included in the exterior lighting power allowance (ELPA). For example, if 50,000 square feet on the West Side of a parking lot has lighting fixtures designed to illuminate that area, and 50,000 square feet on the East side of the parking lot has no lighting fixtures designed to
illuminate that area, a parking lot area of 50,000 square feet shall be used to calculate the ELPA.

Question No.2: Is this interpretation correct?

Answer No.2: Yes.

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As noted by Megan Ritchie-Saffitz above:

"To support the claim that the surface is “designed to be illuminated”, a project team may optionally reference these IESNA values. Other justification supporting the claim that the surface is “designed to be illuminated” will also be accepted."

The ASHRAE Interpretation above provides other justification that can be used to support the claim that the surface is "designed to be illuminated":

* Published minimum recommended illumination levels for the surface type (such as the IESNA Handbook, Zumtobel – the Lighting Handbook, EN
1264-2, local code regulations, etc.).

* Some reasonable lighting design criteria that meets industry standards, good design practice, and client desires.

Oh geeze. Sorry but this is a pretty ridiculous and wishy-washy response. You asked should projects have to meet industry standards for illumination? The answer was no. The comments then state that the intent of the standard is that project should meet industry standards for illumination. Anyone else see a clear contradiction in this response?

If the intent of the standard is to meet industry standards for illumination, why would this interpretation say that projects don't have to meet industry standards? SMH

So what we have is clear as mud and basically unenforceable.