Life-cycle cost assessment and energy performance evaluation of NZEB enhancement for LEED-rated educational facilities

Life-cycle costing (LCC) is increasingly important when making decisions about sustainable buildings such as LEED-certified buildings. For educational buildings, the LCC can be used to identify the cost-optimal solution out of different alternatives such as renewable energy strategies to improve energy efficiency. The application of photovoltaic (PV) panels and the ability to accurately predict power delivery over the course of time play a key role in the life cycle of such sustainable building facilities. Two cost drivers in the performance of this type of renewable energy systems involve the efficiency with which sunlight is converted into power and how this relationship changes over time. An accurate quantification of power decline over time, also known as degradation rate, is essential to all the project stakeholders. In this study, an investment framework is used to compare scenarios for improving the performance of educational buildings, maximize energy savings, and meet the NZEB (net zero energy building) criteria. LCC is used to compare a building ‘base case’ to alternative energy efficiency strategies involving the application of PV panels. Cost and PV panel efficiency over time in are evaluated. The energy payback period (EPBP), simple payback period (SPBP), and return on investment (ROI) are used to measure the economic performance of proposed cost-optimal alternatives. This approach is used to determine the cost-effectiveness of the energy efficiency improvements, considering future operational savings and higher initial investments.