We have a project which qualifies for CS and can be treated as a single building. It is comprised of near 214,180 ft² that will be completely renovated (HVAC and other systems, except the building envelope) and near 83,060 ft² of a new tower. Minimum thresholds for EAp2 compliance under version 3 (2009) is 5% for for existing building renovations and 10% for new buildings. According to version 2.2, cost target savings for projects with new buildings and existing building renovations were calculated based on the target savings for each one and their respective areas, i.e.: target = (exisiting area/ total area) x 7% + (new area/ total area) x 14%. Hence, in the case of this project:
1) is the minimum threshold for EAp2 10% or can it be calculated as before, according to version 2.2, i.e. target = (exisiting area/ total area) x 5% + (new area/ total area) x 10%?
2) More than 50% of its gross area will be leasable. In case the methodology explained for minimum thresholds under version 2.2 can be adopted for version 2009, can it be used for CS?
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
July 7, 2014 - 6:03 pm
The same weighted average calculation applies. The EAp2 forms calculate this automatically.
MARCIO OROFINO
ENE ConsultoresENE CONSULTORES
18 thumbs up
July 11, 2014 - 10:40 am
Thank you, Marcus. And a new issue arose during the modeling process: I am aware that, fot the existing building portion of the project, Baseline Building envelope shall reflect the existing envelope prior to alterations. In the case of this project, some glazed areas have been removed, and the window-to-wall ratio of the Proposed Building happens to be less than the WWR of the Baseline Building. On the other hand, Appendix G states that WWR of Baseline shall be equal or less than the WWR of the Proposed model. How shall we proceed?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
July 11, 2014 - 10:27 am
Those existing glazed areas just became new construction and are no longer existing. Treat the infilled windows as new walls using the Baseline minimum values and the actual U-value in the Proposed. Model the window area the same in both models. I think that this is the conservative approach.
You technically could probably do it the other way and explain the difference in the window areas.
Basically if you are forced to choose between two Baseline requirements, pick the one that generates the most conservative result.
MARCIO OROFINO
ENE ConsultoresENE CONSULTORES
18 thumbs up
July 11, 2014 - 10:55 am
Thank you for the prompt response, Marcus. But I have just read in the Advanced Energy Modeling for LEED that, for existing buildings, we shall "model building envelope using (pre-retrofit) building envelope thermal parameters rather than referenced standard's prescriptive building envelope requirements for specified climate" (page 7, Table 2.1, ASHRAE 90.1-2007, Baseline Case, Building Envelope). In order to avoid future problems during certification I'll use a safe margin in case the reviewer asks to use the conservative approach you have suggested.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
July 11, 2014 - 11:21 am
Comparing walls to windows ends up violating the Baseline modeling protocols too. All you need it Table G3.1-5 Baseline to tell you how to model the Baseline envelope. What you have identified is a conflict in the requirements. Pick the one that gives the most conservative result and be sure to point out to the reviewer that you have done so.