Integrated solar thermal systems in smart optimized zero energy buildings: Energy, environment and economic assessments

An innovative energy optimization algorithm is employed for an existing office building. This optimization is done to decrease energy usage and increase the building's energy efficiency. Apart from this optimization, an efficient solar thermal system is used for reducing building CO2 emissions. In addition, to achieve more significant CO2 reductions, the feasibility of transforming the existing building to a zero-energy building is analyzed. Optimization is done using accurate data and DesignBuilder simulation software. Then, by detecting inefficiencies, objective functions are proposed for the case study. Based on the air heating and domestic hot water loads, an efficient solar thermal system is modeled. Various energy resources are considered to supply hot water and space heating, including solar energy, electricity, and natural gas. Finally, the feasibility of converting the building to a zero-energy building is evaluated using TRNSYS software. A feasibility analysis is performed using electricity consumption data from DesignBuilder software. The building optimization results in a significant reduction in fuel consumption and carbon dioxide emissions. Adding a solar thermal scenario raised the thermal efficiencies of the system to 47%. Economic calculations demonstrated the solar thermal system's financial merits. In this case, the solar thermal system can save about $318 annually. To convert the building to a zero-energy building, at least twenty-four 2 kW wind turbines, three 9 kW wind turbines, and 460 m(2) of photovoltaic panels must be used. These values are obtained by assuming efficiencies of 100% for inverters and transformers. But to achieve zero energy building status on a monthly basis, a higher number of renewable energy suppliers must be used. Based on the rooftop area (340 m(2)), separate land close to the building must be considered for mounting some of these renewable energy suppliers, apart from the rooftop.