LAUSR

Abstract Energy consumption and CO2 emission are increasing in the world. Although many countries are trying to remedy this problem, Iran and some others have fallen behind. Utilization of renewable energies via passive systems is one of the important aspects of environment-friendly architecture but many practitioners of this field still struggle with using them. The aim of this study is to provide a decision-making method which would help these practitioners decide which passive systems are best suited for their projects. The present paper proposes a method based on three indexes: Potential (P), Sufficiency (S) and Efficiency (E). The Potential index is calculated based on the natural properties of passive systems and effective environmental factors. The Sufficiency index concerns the calculation of those times in the year for which using that system can result in a comfortable thermal condition inside the building. The Efficiency index compares different systems in terms of the ratio of produced energy to the occupied space in the building by the system. The proposed method is used to calculate a quantitative value for using passive direct gain systems, Trombe walls, and greenhouses in Tehran. The calculated PSE indexes are 0.6073, 0.4930 and 0.1253 ( k W h m 3 ) for the direct gain system, unventilated Trombe wall, and greenhouse, respectively. Study of other cities in Iran showed that passive heating systems are very useful in most parts of the country. The proposed method produces quantitative guidance for comparing passive heating systems in different climates. This research contributes to building energy conservation, specifically the application of passive. This method is mainly proposed for Iran or other similar developing countries but not limited to a specific region. The PSE Index for the mentioned passive systems is calculated and presented for 5 cities in Iran, each having different climate conditions.