Page 201 - The Engineering Guide to LEED-New Construction Sustainable Construction for Engineers
P. 201
LEED Ener gy and Atmospher e 179
Intent
Encourage the development and use of grid-source, renewable energy technologies on a
net zero pollution basis.
Requirements
Provide at least 35% of the building’s electricity from renewable sources by engaging in at
least a two-year renewable energy contract. Renewable sources are as defined by the Center
for Resource Solutions (CRS) Green-e products certification requirements.
DETERMINE THE BASELINE ELECTRICITY USE
Option 1: Use the annual electricity consumption from the results of EA Credit 1.
OR
Option 2: Use the Department of Energy (DOE) Commercial Buildings Energy Consumption
Survey (CBECS) database to determine the estimated electricity use.
Potential Technologies and Strategies
Determine the energy needs of the building and investigate opportunities to engage in a green
power contract. Green power is derived from solar, wind, geothermal, biomass or low impact
hydro sources. Visit www.green-e.org for details about the Green-e program. The power
product purchased to comply with credit requirements need not be Green-e certified. Other
sources of green power are eligible if they satisfy the Green-e program’s technical requirements.
Renewable energy certificates (RECs), green tags and other forms of green power that comply
with Green-e’s technical requirements can be used to document compliance with EA Credit 6
requirements.
Calculations and Considerations (LEED 2009)
EAc6 is based on either purchasing or trading electricity from renewable off-site power
sources for at least 35 percent of the defined electricity needs for the project during two
years. The definition of renewable power sources is per the Center for Resource
Solutions’ Green-e Product Certification Requirements, which can be found at www.
green-e.org. The electricity can be purchased from the local power provider, if available.
If the “green” electricity is not directly available, but the area provider has a green
power program, then the contract can include enrollment into this program with its
additional premium to facilitate green power usage elsewhere. If the area provider
cannot offer either of these options, then there is also the opportunity to purchase
Green-e renewable energy certificates (RECs), In this case, power is purchased locally,
and the RECs for the calculated amount are purchased. The RECs represent the premium
needed for purchasing renewable power elsewhere in the country and facilitate its
widespread use.
The threshold value of green power purchased is based on the electrical power
needs portion of the energy model if the EAc1 Option 1 is sought. Otherwise, it is based
on the electrical power needs portion of the building annual energy cost (BAEC)
calculation as outlined in EAc2. Either way, electricity cost rates do not have to be
evaluated since only the electrical power needs are being analyzed, and there is no need
to have a cost-based bridge for adding different power usage impacts. The sets of
calculations based on the BAEC method and the EAc1 Option 1 energy model method
are described in the following paragraphs.
Based on the BAEC method when the EAc1 Option 1 is not sought, the building
annual energy usage of electricity (BAEE) can be found by using the median annual
electrical intensities for the particular building type (CBECSE ) as listed in Table 4.2.3
j
under EAc2. The calculation for BAEE is given in Eq. (4.6.1). [This is the electricity