Optimization of the renewable energy system for nearly zero energy buildings: A future-oriented approach

Renewable energy systems (RES) in buildings are designed to operate over their lifetime. Considering only present-day data in the pre-project planning phase, which is common in optimization studies, without taking into account the potential future changes in influential parameters such as climate and energy price data may lead to inappropriate solutions for long-term operation. Therefore, this study aims to present a future-oriented optimization methodology for RES design able to adapt to the impacts of climate change and variations in energy prices. Future climate and energy price data are used to obtain the optimal design of a RES proposed to cover the energy demand of a nearly zero energy building (nZEB), and the results are compared with those obtained from present-day data. Results show a decrease in heating and electricity demand by 14.6% and 2.29%, and an increase in cooling demand by 19.9% after 20 years. It is found that the RES design based on present-day data is vulnerable to the impacts of climate change and energy price variations. It leads to an oversized system for meeting electrical and heating demand while lacking sufficient capacity to cover the cooling needs in the future. A comprehensive energy analysis is also conducted concerning climate change impacts on the RES performance, and an upward trend in on-site generation and load matching index is concluded. Sensitivity analyses were performed for some economic parameters. The findings prove that the proposed methodology guarantees the reliability of RESs to fulfill nZEB requirements from a long-term perspective.