Forum discussion
NC-2009 EAp2: Minimum Energy Performance
We have a building that contains both existing and new construction. I wonder how we should determine the LEED points we will achieve given certain percentage savings. Is it based on 60% rule?
Thanks in advance
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
July 31, 2015 - 9:24 am
The % savings is calculated based on a weighted average of new to existing area for the project. So for example if the area is 50% new and 50% existing you would split the difference between the 10% (new) and 5% (existing) and would need 7.5% to meet the prerequisite requirements.
Haojie Wang
Energy ModelerKJWW Engineering
4 thumbs up
July 31, 2015 - 10:04 am
Thanks Marcus. How we should document this on LEED online? It doesnt give us an option to input the savings for new and existing separately. Instead, it automatically calculate the savings and points achieved.
Also, the building has three part: new, renovated existing and unrenovated portion.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
July 31, 2015 - 10:00 am
The prerequisite form will accurately calculate the percentage and points based on the ratio of new to existing area. This information gets entered in one of the project information forms and automatically transfers to the EAp2 form within LEED Online.
Haojie Wang
Energy ModelerKJWW Engineering
4 thumbs up
July 31, 2015 - 10:13 am
Let me elaborate my question: I can enter the % of new and existing floor area but cant enter the savings % for them. Also, I modeled all those spaces in the same model so I don't know if it is possible to separate the savings for each portion. Especially the cooling, heating and fan energy cannot be separated easily since they have non-linear curve. And another thing is that, once we have the savings, say 15% prorated, how many points should we get? Are we using New buildings or existing threshold?
I wonder if the reviewer can accept if the building has more than 60% existing area, we can use the existing building threshold
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
July 31, 2015 - 11:23 am
You don't enter the % savings. The form calculates it.
You don't separate the savings for each portion. The weighted average is applied to the total.
You are using a blend of new and existing to determine the thresholds for the points. In my previous example (50% new, 50% existing) the prerequisite starts at 7.5%, 1 point would be 10%, 2 points would be 12%, 6 points would be 20%, etc. Basically you are creating your own set of thresholds for the points based on the ratio of new to existing in your project.
No a 60% existing area cannot use the existing thresholds. It just does not work that way.
Haojie Wang
Energy ModelerKJWW Engineering
4 thumbs up
July 31, 2015 - 11:55 am
Thanks for the clarification Marcus. It is clear to me now.