This just... USGBC changes to CS energy modeling requirements

Hi Seema,

My project team emailed the GBCI with questions about this memo. It appears that you aren't actually required to use it. Please see below for our qustions and their respones.

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Hi Lauren,

I received back some information from GBCI - In short, you are not required to use this guidance/spreadsheet calculator, regardless of the wording of the Information memo (https://www.usgbc.org/ShowFile.aspx?DocumentID=6926), so our apologies for the confusion. However, it is usually (but not always) advantageous to utilize the spreadsheet.

The intent and effect of this guidance is to provide LEED-CSv2.0 projects with lower EAc1 percentage thresholds than were previously required. Since owners/developers often cannot influence tenant building loads, it is unreasonable that they be held fully responsible for these loads in the energy model. The new calculations spreadsheet essentially accounts for the portion of the loads they can’t influence, and lowers the EAc1 percentage improvement point thresholds accordingly.

See additional comments in red below.

My team has a project that is registered under LEED-CS 2.0 and has questions regarding the memo released by the USGBC called: “LEED-CS v2.0 amended documentation requirements.”

Description of rule: https://www.usgbc.org/ShowFile.aspx?DocumentID=6926
Excel spreadsheet tool: https://www.usgbc.org/ShowFile.aspx?DocumentID=6927

First, is the memo still active for LEED-CS 2.0 projects or is there something new that has been released that is more clear? We find it to be fairly confusing, even after reviewing it many times. May we elect to not use this clarification memo and instead use the LEED-CS Reference Guide for our approach?

"YES. You may elect not to use it. Although the wording of the Information memo suggests otherwise, projects cannot be held to prerequisite/credit requirements (CIRs, supplemental guidance, etc) that are introduced after the project is registered. Apologies for any confusion."

General Questions:

1) Excel worksheet called “CS v2 EAc1 Table”

a. Which section is the one used for calculating the # of points a project gets, the “% of Core and Shell Building Load”, or “% of Whole Building Load”? I am presuming that we use the “% of Core and Shell Building Load”, but this makes me wonder why is there a % savings vs. point thresholds for the “% of Whole Building Load” column.

"Actually, after entering the "Percentage of Energy Cost Influenced or Directly Controlled by CS Owner/Developer", you utilize the "Savings as a % of Whole Building Load" to determine the percentage thresholds to be used as the basis for EAc1 point achievement. Please note that when the percentage influenced/controlled by the Owner/Developer is less than 75%, the " Savings as a % of Whole Building Load" are lower than the standard EAc1 point thresholds. However, projects are not meant to be penalized by this new calculation, so if the revised thresholds of the new calculator are not advantageous, you may choose not use this new calculation in your application and explain why you are doing so in your Narrative for EAc1."

2) If we exclude non-owner controlled items from the baseline and proposed models and then use the numbers on the “% of Core and Shell Building Load” side of the table, are we following the credit rules?
"You do not need to change the basic modeling methodology in order to apply this new guidance and/or the new point thresholds. In other words, you do not exclude Tenant spaces or energy loads from the Proposed or Baseline models to apply this guidance. Instead, if, for example, the modeling (done in accordance with the instructions in Appendix2 of the LEED-CS v2.0 Reference Guide) results in a projected performance improvement of 15% for a new construction project, and the percent of energy cost controlled/influenced by the Owner/Developer were determined to be 50%, the project would be eligible for 4 points instead of only 2 under EAc1. See also the "Instructions" tab of the LEED-CS v2.0 EAc1 Amended Calculator Spreadsheet (https://www.usgbc.org/ShowFile.aspx?DocumentID=6927)."

3) How do we document the calculations for this credit? How do we use (or not use) the online letter template? The template mentions nothing of this rule. Do you have an example of the documentation that has been provided on other projects?
"Documentation for the credit is basically the same as prior to the new guidance, but you provide the completed calculator spreadsheet along with your documentation, and, in some cases, some additional separate meters may be required in the modeling to properly account for the separation of tenant and owner energy loads. More detailed information is provided in the "Instructions" tab of the LEED-CS v2.0 EAc1 Amended Calculator Spreadsheet (https://www.usgbc.org/ShowFile.aspx?DocumentID=6927)."

4) Text says that this spreadsheet is "required" submittal documentation. Does that just mean we have to fill in the green square on the worksheet called “CS v2 EAc1 Table” or do we need to do more?
"On the calculator spreadsheet, you just need to complete the green cell, but you should also include information in your Narrative to explain how the the percentage influenced or controlled by the owner/developer was determined and provide the information discussed in the Instructions tab of the calculator spreadsheet cited above. Additionally, you should use the Alternative Compliance checkbox on the credit submittal Template and fill in the point value per the calculator results."

5) There is a 0.75 multiplier used to calculate the “% of Whole Building Load” point thresholds. What is this for?

"Although I do not have the background information necessary to provide detailed explanations of the exact ratios/calculations used at this time, the intent and effect of this guidance is to provide LEED-CSv2.0 projects with lower EAc1 percentage thresholds than were previously required. Since owners/developers often cannot influence tenant building loads, it is unreasonable that they be held fully responsible for these loads in the energy model. The new calculations spreadsheet essentially accounts for the portion of the loads they can’t influence (which varies by project), and lowers the EAc1 percentage improvement point thresholds accordingly."

Hi Lauren,

I wrote the spreadsheet and will take any blame for confusion. This was the result of a long set of discussions with numerous CS developers in response to the differences between the CS modeling protocol under the pilot and when CSv2 was released.

The 0.75 multiplier is to normalize this data with NC projects which are assumed to have 25% process loads as a default.

OK, thanks Marcus. I understand that it is only meant to assist project teams. With the clarifications provided, I think we are all set.

Marcus,
Going back to a very old thread, but I'm hoping you can help clarify for me the proper use of the CS Alternative Calc spreadsheet. When determining the %Owner Controlled Cost is that calculated from the Baseline model results? The value would be lower if you used the Proposed model results (assuming there is some efficiency in the design!).

The Proposed. The owner can't control or influence anything in the Baseline. :-)

Also I do not think that this spreadsheet has ever been approved for use in LEED CS 2009 projects, only v2.

A CS 2009 version is on the USGBC website. I would give the address but it seems to be down again. I'll post it later. It makes more sense to me that the baseline usage is the starting point for determining the % of the total load that the owner controls. Any reductions from that load are the result of measures implements (controlled) by the owner. But if it is the Proposed loads as you say, then the resulting EAc1 points are much higher!

The CS 2009 spreadsheet link is http://www.usgbc.org/resources/cs-2009-eap2-c1-acp.

Thanks Erik. I stand corrected.

Hi Marcus - the spreadsheet available at that link has an incorrect formula. It always has. We had been instructed to just edit the document to correct it for a USGBC submittal. But I did want to alert everyone. for example: enter 65% as the percent owner controlled. according to the instructions, this should only affect the prereq, but it also adjusts the point tiers for anything above 10 points. We have an in-house version that has "corrected" formulas if you would like to see that.

It should adjust all of the point tiers and does affect more than the prerequisite. It also impacts the points for EAc1.

While I authored the concept and the original spreadsheet, GBCI made some modifications to the one posted and should be the one to fix it (I can't).

Thanks for pointing out the issue.

I looked a bit closer. The version used in CS v2 did make adjustments to all the points.

In the LEED 2009 version there is that note about a sliding scale. The spreadsheet appears to adjust more of the thresholds as the percentage goes down. I do not understand the logic behind this sliding scale or why some of the thresholds do not adjust. Maybe someone at GBCI could explain.