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The global contribution from buildings towards energy consumption, both residential and commercial, has steadily increased, reaching figures between 20% and 40% in developed countries, and has exceeded the other major sectors: industrial and transportation (Perez-Lombard, Ortiz, & Pout, 2008). In the United States buildings consume close to 40% of all energy used and account for 40% of global CO2 emissions (Schlueter & Thesseling, 2009). Growth in population, increasing demand for building services and comfort levels, together with the rise in time spent inside buildings, assure the upward trend in energy demand will continue in the future. For this reason, energy efficiency in buildings is a prime objective for energy policy at regional, national and international levels.
In addition, the rising cost of energy and growing environmental concerns have pushed the demand for sustainable building facilities with minimal environmental impact through the use of environmental sensitive design and construction practices (Azhar, Brown, & Farooqui, 2009). In efforts to alleviate resource depletion and environmental damages, the Architecture, Engineering, and Construction (AEC) industry has adopted Integrated Project Delivery (IPD) as a highly collaborative building procurement process supported by some prominent technological solutions and tools, such as the United States Green Building Council (USGBC) Leadership in Energy and Environment Design (LEED) rating system and Building Information Modeling (BIM) (Garzone, 2006).
LEED is a green building certification system which encourages a building or community to be designed with consideration of environmental impact, energy savings, and human comfort (Gowri, 2004). A LEED rating rewards designers for using strategies that can improve performance in metrics such as CO2 emissions reduction, water efficiency, energy savings, indoor environmental quality, and other environmental impacts. Although LEED does not guarantee most efficient performance of a building or community, it is one method to help towards this goal (Todd, Crawley, Geissler, & Lindsey, 2001).
Building Information Modeling (BIM) represents the development and use of computer-generated building model to support the planning, design, construction and operation of a facility. This technology helps architects, engineers and constructors collaborate and visualize what is to be built and identify potential design, construction or operational problems in a simulated environment (Azhar & Brown, 2009). Linking the building model to energy analysis tools allows for evaluation of energy use and can reduce the costs associated with traditional energy use patterns during building operation.
BIM can support the study of alternatives more quickly, to achieve LEED certification, and make timely decisions (Patel, 2012). Despite the LEED certification process for the new construction, it is required to evaluate the building performance during its operation phase and recertify the building under LEED points. In cases when LEED certified buildings do not perform as expected in the filing period, building performance needs to be analyzed and optimized during operation (Newsham, Mancini, & Birt, 2009). Buildings can apply for recertification as frequently as each year but must file for recertification at least once every five years to maintain their LEED for Existing Buildings: Operations & Maintenance status (Council, 2008).
The research points to discontinuities between photovoltaic panel degradation over time and the LEED credit. Alternative renewable energy scenarios are evaluated to make recommendations for the optimization of building performance and its capacity to achieve Zero Net Energy (ZNE), in terms of energy consumed vs. energy generated during building operation.