A Modern Classification of Passive Fresh Air Flow-Generating Strategies in Breathable Architecture with Multi-Criteria Evaluation in Four Climates of Iran

With the escalating global energy crisis and the growing imperative to mitigate greenhouse gas emissions, the building sector has faced immense pressure to reduce its heavy reliance on energy-intensive mechanical heating, ventilation, and air conditioning (HVAC) systems. Concurrently, with the increasing attention paid to indoor air quality (IAQ) and its direct impacts on occupant health, comfort, and productivity, the necessity of redefining and integrating passive strategies for fresh air circulation in sustainable and bioclimatic architecture has become more apparent than ever. A comprehensive review of the existing literature indicates that despite the historical introduction and modern development of numerous passive design strategies, a significant void remains. Specifically, the lack of a comprehensive, structurally oriented physical classification, coupled with the absence of a precise, multi-criteria evaluation of these strategies’ actual performance across the highly diverse and distinct climatic zones of Iran, still remains a serious scientific and practical gap.

Consequently, the primary aim of this research is to bridge this gap by presenting a novel, comprehensive classification framework based on physical-functional logic, and subsequently, to prioritize these passive ventilation strategies across the four main climates of Iran (hot-dry, hot-humid, temperate-humid, and cold-mountainous).

To achieve these objectives, the present study was structured as applied research, conducted using a rigorous mixed-methods approach. In the first qualitative phase, through a systematic and extensive literature review, 17 distinct passive ventilation strategies were identified and innovatively classified into four primary spatial categories based on their physical integration into the building envelope: roof-based, wall-based, transitional spaces, and floor-based systems. Following this, in the quantitative phase, with the active participation of a panel consisting of 63 recognized academic and industry experts in the field of sustainable architecture, 8 critical evaluation criteria were extracted. These criteria were then objectively weighted using the Shannon entropy mathematical method to eliminate subjective bias. Subsequently, the identified strategies were rigorously ranked within the specific context of the four distinct Iranian climates using the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) multi-criteria decision-making method, alongside a detailed investigation into potential synergy patterns among the varying strategies.

The comprehensive results demonstrated that “ventilation efficiency” and “indoor air quality” emerged as the most heavily weighted and important decision-making criteria for system selection. Furthermore, the analysis conclusively revealed that the performance and viability of the strategies are significantly and intrinsically dependent on the specific climatic context. For instance, natural openings and optimized interior spatial layouts exhibited the highest efficiency in both temperate-humid and hot-humid climates. Conversely, traditional windcatchers and central courtyards proved to be the optimal choices for managing the severe thermal conditions of the hot-dry climate. Meanwhile, strategic window placements, Trombe walls, and solar chimneys demonstrated peak performance in the harsh cold and mountainous climate by effectively balancing ventilation requirements with thermal retention.

Ultimately, the findings conclusively indicate that effective and sustainable passive ventilation is not merely the result of selecting and installing a single architectural element. Rather, it emerges organically from the intelligent, holistic combination of complementary elements, creating vital synergistic effects, and demanding precise, calculated adaptation to the localized climatic context.