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180    Cha pte r  F o u r


             portion of Eq. (4.2.1) and does not include cost rates.] The GFA in Eq. (4.6.1) is the gross
             floor area of the building as defined in Chap. 2. If the project is made up of several
             buildings or building portions with different uses as listed in Table 4.2.3, then the
             commercial building energy consumptions (CBECSE ) for electricity should be separately
                                                         j
             analyzed for each portion, multiplied by the gross floor area in that building portion,
             and summed to obtain the BAEE.
                         BAEE = (CBECSE )(GFA)    if EAc1 Option 1 is not sought   (4.6.1)
                                       j
                 On the other hand, the basis for the electric usage when EAc1 Option 1 is sought
             is a portion of the Proposed Building Performance (PBP) as previously calculated in
             Eq. (4.1.1). In LEED-NC 2.1, a point was earned in EAc6 if the green power purchased
             was at least 50 percent of the difference between all regulated electricity loads and the
             electricity provided by on-site renewal energy sources. For this earlier version, the
             EAc1 calculations were all based on regulated loads. In LEED-NC 2.2, the calculations
             for EAc1 Option 1 are based on both regulated and nonregulated loads for which the
             nonregulated loads are assumed to be approximately 25 percent of the regulated
             loads. (Nonregulated loads are sometimes referred to as process loads.) Therefore, the
             threshold in LEED-NC 2.2 has been reduced to 35 percent to take into account the
             calculation changes. In LEED-NC 2.1, the modeled energy electrical use was further
             modified to account for on-site renewable energy production. Keeping this modification
             in LEED-NC 2.2 and carried forward to LEED 2009, the author has interpreted that the
             calculation appropriate for the first compliance path (EAc1 Option 1)  should again
             include this reduction in the denominator of the on-site renewable energy, so that
             the percent green power purchased is truly only the percent of the demand from the
             off-site grid.
                 Keeping this modification in mind, let PBE (proposed building electrical performance)
             be the electrical energy portion of the PBP as defined in EAc1 Option 1. If PDEE is the
             proposed design electrical energy portion (in electrical usage units) as given from the
             proposed design energy model (PDEM), then the PBE is the difference in the electrical
             usage portion of the PDEM in units of electrical power per year (PDEE) and the electrical
             portion of the annual on-site renewable energy (REC) in units of electrical power per
             year (REE).

                             PBE = PDEE − REE    if EAc1 Option 1 is sought      (4.6.2)


             Using the annual amount of green electricity (GE) purchased or traded from off-site,
             and the definitions for proposed building energy needs, PBE and BAEE, based on the
             EAc1 Option 1 compliance pathway and other energy calculation pathways, respectively,
             the percent green electricity (PGE) can be calculated for each as

                                          GE
                            PGEPB =  100 ×       if EAc1 Option 1 is sought      (4.6.3)
                                         PBE

             or alternatively

                                          GE
                         PGEPB =  100 ×              if EAc1 Option 1 is sought   (4.6.4)
                                           −
                                      PDEE REE
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