Thermal performance analysis of a liquid wall vs. argon-filled double glass window in identical prototype buildings

This study investigates the thermal performance of a liquid wall panel in comparison with an argon-filled double-glass window, applied to identical prototype buildings located in Tirana, Albania. The analysis focuses on heat transfer mechanisms, including thermal resistance, thermal mass, energy storage capacity, transient thermal behavior, and associated CO₂ emissions. The study is based on a comparative analysis of two cubic prototype buildings (3 × 3 × 3 m) with identical insulated walls, floors, and terraces (U-value 0.40 W/m²K), differing only in the southern façade: an argon-filled double-glazed window (1.1 × 0.93 m, 10 mm argon cavity) versus a liquid wall panel (2.5 × 2.8 m, 80 mm water layer). Analytical heat-transfer calculations and simplified dynamic assessments were applied, including U-value estimation, thermal mass and energy storage calculations, transient heat conduction analysis, and heat-loss quantification. Additional considerations for the liquid wall included internal convection, evaporative cooling, and solar absorption. CO₂ emissions were estimated based on heating energy requirements and seasonal performance. The results indicate that the liquid wall provides higher thermal mass and improved thermal stability, reducing peak indoor temperature fluctuations and enhancing comfort. However, its lower thermal resistance compared to argon-filled glazing may increase heat losses, particularly in winter. In Tirana’s climate, argon-filled façades offer more consistent year-round insulation, whereas liquid walls can support passive solar heating if properly controlled to avoid summer overheating. Thermal performance of the liquid wall is influenced by system design, material properties, local weather, and maintenance factors. A hybrid strategy combining the thermal mass of a liquid wall with the insulating performance of argon-filled glazing is suggested to optimize seasonal energy efficiency and comfort. The findings provide insights for the design of liquid wall façades and highlight the potential integration of microalgae systems to reduce carbon dioxide emissions.