cove.tool follows LEED v4.0 BD+C: New Construction methodology for calculating potential EAc2 LEED Points on the baseline page. The requirements of this credit are to compare the proposed building's Performance Cost Index (PCI) against a baseline model defined by ASHRAE Standard 90.1-2010, Appendix G. To accomplish this cove.tool uses information about each project to determine the correct baseline inputs to start off with.
If users are attempting to follow the new LEED v4.1 BD+C: NC methodology to estimate their project's EAc2 LEED points, then they'll need to use the Energy Code Determination DOE performed for each code to determine the potential LEED v4.1 EAc2 points that they'd get for their project, which will naturally be lower than what cove.tool estimates.
The DOE Determinations serve the purpose of estimating the degree to which the latest edition of ASHRAE Standard 90.1 will improve energy efficiency compared to the previous edition of the corresponding standard or code. Below is a table that describes the successive energy savings between energy codes:
ASHRAE Standard referenced for calculating EAc2 LEED Points
Estimated Improved PCI from the previous standard edition
For example, let's say there's a project built using ASHRAE 90.1-2010 baseline prescriptive values that has a PCI of $100K/year. The LEED v4 EAc2 points it gets would be 0 because LEED v4 is using an ASHRAE 90.1-2010 baseline model as the comparison.
If it were built using ASHRAE 90.1-2013, it could have an estimated ECI of:
($100K/year - ($100K/year * 8.3%)) = $91.7K/year, or 2 LEED v4 EAc2 points.
If it were built using ASHRAE 90.1-2016, it could have an estimated ECI of:
($91.7K/year - ($91.7K/year * 8.7%)) = $83.7K/year, or 6 LEED v4 EAc2 points.
If it were built using ASHRAE 90.1-2019, it could have an estimated ECI of:
($83.7K/year - ($83.7K/year * 4.3%)) = $80.1K/year, or 7 LEED v4 EAc2 points.
Now let's say the project is attempting to achieve LEED v4.1 certification. Any project designed in accordance with prescriptive requirements from an ASHRAE 90.1 version 2016 and earlier would automatically not be considered. Their project would need to perform at least 5% better than ASHRAE 90.1-2016 prescriptive requirements in order to start achieving the LEED v4.1 EAc2 points. If it were built using ASHRAE 90.1-2019, then according to the table above, it would have a PCI that would only improve by 4.3% as compared to ASHRAE 90.1-2016, which isn't enough to acquire a single point for this credit.
Check out other LEED-related resources below to see how else cove.tool can help you pursue a USGBC Certification.