The window-wall ratio is a key envelope parameter that governs daylighting

natural ventilation

and thermal performance in residential buildings. Currently

two extreme design practices prevail: the indiscriminate use of full-height floor‑to‑ceiling windows

and the excessive reduction of window openings. Both approaches readily give rise to glare

insufficient illuminance

disordered airflow

uneven indoor cooling/heating

and increased building energy consumption. This paper systematically examines the indoor environmental deficiencies caused by an imbalanced window-wall ratio from three perspectives – lighting and visual comfort

ventilation and air quality

and thermal energy performance. Based on the concept of multi-objective collaborative design

three optimization pathways are proposed: orientation‑based hierarchical shading and daylighting strategies

façade‑differentiated combined ventilation layouts

and climate‑adaptive high‑performance envelope constructions. The findings indicate that no single fixed window-wall ratio can simultaneously satisfy occupant comfort and low‑carbon energy conservation. Instead

the design should holistically regulate the glazing ratio according to building orientation

regional climate

and apartment layout

while integrating shading devices

energy‑efficient glazing

and layered ventilation systems for synergistic optimisation. This study offers theoretical and practical guidance for the refined façade design of green residential buildings.