Points for EAc4 cannot be achieved based on system specifications that utilize performance period data for sizing in lieu of actual solar system performance monitoring during the performance period. Unlike the LEED Rating Systems for New Construction, Core & Shell and Schools, the LEED 2009 Rating System for Existing Buildings: Operations and Maintenance is a whole building rating system designed to certify the sustainability of the ongoing daily operations of existing commercial and institutional buildings. As such, EB O&M is comprised of a planning, implementation and performance period measurements for each of the prerequisites and credits. EAc4: On-site and Off-site Renewable Energy, as its name implies, has two pathways to obtain up to six points. During the performance period some or all of the buildings energy may be met with On-site and Off-site Renewable Energy. If the solar PV system is not installed and operating during a portion of the performance period to confirm performance, the project team may consider the purchase of renewable energy certificates (RECs) to demonstrate credit compliance. In lieu of the commitment to purchase RECs on a continuing basis, a commitment to provide a percentage of the buildings total energy consumption generated on-site at the conclusion of the RECs purchase may be considered. That would allow additional time to complete the design and installation of the solar PV array. Applicable Internationally.