Natural ventilation (NV) is a key energy-efficient strategy for improving indoor air quality and thermal comfort in residential buildings. In cold climates such as Poland, the dominant form of NV is stack (chimney) ventilation, whose effectiveness depends on temperature differences and wind conditions. The aim of this study was to evaluate the impact of different chimney configura-tions on air change intensity (ACH) in a real residential building in Gdańsk. During a four-month measurement campaign, three solutions were compared: a traditional brick chimney (Type I), a solar chimney with a glazed extension (Type II), and a chimney equipped with a rotary cap (Type III). Results showed that, compared to the baseline configuration, the solar chimney increased the ACH by an average of 14% under favorable solar conditions, while the rotary cap improved ACH by up to 35% in moderate wind conditions. The study confirms that even small passive modifications to chimneys can significantly en-hance the stability and efficiency of stack ventilation. The findings provide practical design guid-ance for architects and urban planners, especially in the context of retrofitting existing buildings and designing new urban developments tailored to local climate conditions.