Investigating the potential for realizing life cycle net-zero energy buildings in Europe using multi-objective optimization

In pursuit of the long-term target of achieving climate neutrality by 2050, it is crucial to strive for buildings with net-zero energy balance from a life cycle perspective. This study employs multi-objective optimization, specifically the non-dominated sorting genetic algorithm II, to explore the feasibility of achieving a life cycle net-zero energy balance for a building case in diverse European climate conditions: including Gothenburg's humid continental climate (characterized by warm to hot summers and cold, snowy winters), Frankfurt's oceanic climate (featuring short, cool summers and long, relatively mild winters), and Madrid's Mediterranean climate (marked by wet, mild winters and dry, hot summers). The study examines this feasibility across three building lifespan durations: the standard 50 years, commonly applied in life cycle analyses, as well as extended lifespans of 100 and 150 years. This examination is vital due to the impact of longer building lifespans, resulting in increased operational energy demand and higher embodied energy due to the more frequent replacements of building components and systems. The findings demonstrate the feasibility of realizing a life cycle net-zero energy building across diverse European climatic conditions and lifespan durations through the identification of optimal passive, active, and renewable measures. The results emphasize the essential role of renewable measures, such as photovoltaic (PV) panels, in effectively offsetting any surplus energy use throughout the building's life cycle, ultimately enabling the achievement of a life cycle net-zero energy building. It was observed that a minimum of 276 m2 (approximate to 63.5 kWp), 246 m2 (approximate to 56.5 kWp), and 131 m2 (approximate to 30.1 kWp) of PV panels would be required to realize a life cycle net-zero energy building in Gothenburg, Frankfurt, and Madrid, respectively. Across all locations and lifespan durations, these PV panels were integrated with optimal active measures, which included geothermal heat pumps for heating, internal air conditioning units for cooling, and mechanical ventilation systems with heat recovery potential. However, the results also indicate that relying solely on active and renewable measures, without incorporating appropriate passive approaches, is insufficient to fully realize life cycle net-zero energy buildings.