One of the most important sustainable building design goals is energy performance throughout the life cycle of the building. In this paper, the optimization of an office building facade has been performed using a genetic algorithm with the sustainability approach. Multi-objective optimization using an SPEA-2 algorithm gives the amount of solar radiation received by the building's envelope, the useful interior space and shape coefficient of design and based on the cooling load, the heating load, and the natural light supplied to the building. In order to achieve the project objectives, parametric modeling was used with the Grasshopper software and environmental analysis tools, Ladybug and Honeybee. In both optimization steps, the optimal solution was selected on the Pareto front and, according to the designer, the decision was made between the optimal results. Optimization has led to an improvement in usable space, reduced thermal load, and improved natural light in the building. Using Pareto front, genetic algorithm and parametric modeling have a significant role in developing a sustainable design. The process and results of this research help architects and designers to find a more sustainable design and facade for the building.

Delays in achieving projects' objectives according to the planned schedule are considered one of the main sources of conflicts in Iran's construction industry. A precise and structured methodology and baseline to properly evaluate the root causes of delays and present guidelines has not been established, to the best of the authors’ knowledge. Therefore, there are limited perspectives on the effects of delays on the projects, creating an inefficient approach to deal with construction delays. The purpose of this study is to identify the most significant causes of construction delays, categorize and rank them to determine the root of delays, and provide a suitable solution. After extracting the main causes of delays through a comprehensive literature review and interviews, a structured questionnaire was designed to rank the delays in terms of three indices of importance, occurrence probability, and impact. In addition, when the causes of delays were identified and classified, the causes were split into eight main groups including the contractor, owner, design, procurement, equipment, consultant, labor, and miscellaneous, and the results were depicted using a cause-and-effect diagram. The findings show that the fundamental group causing delays was the contractor category, and the most critical cause was the contractor's financial problems. The primary conclusion of this study is that financial matters play a critical role in project delays in Iran's construction industry, and it is recommended that owners should take more meticulous measures to choose the most qualified contractor with strong financial backgrounds and they need to define and phase the project to their financial resources and determine an efficient financial plan for payments.

Because of the complexity of construction projects, the use of building information modeling (BIM) has become a more efficient solution. The main problems with conventional methods, such as the critical path method and program evaluation and review technique, are the lack of precision in predicting time due to the dynamics of the construction process. One solution is to combine planning models with discrete event simulation (DES) and BIM to simulate the dynamic environment to reduce uncertainties. Likewise, DES is used to implement just in time (JIT). A problem with JIT implementation using DES in the construction industry is a lack of accurate measurement of the optimum time for each process. Meanwhile, takt time, one of the main techniques in JIT, was used in this research to achieve the optimal time of each process and was combined with DES to solve this problem. First, a 4D BIM model was developed to extract data. Then, takt time was used to achieve optimal time for each activity, and eventually, a DES was performed. The results of this study indicate that the proposed framework using takt time and its combination with DES to integrate BIM with JIT will lead to realistic and optimal planning.

The suitability of the project delivery system (PDS) selected for a project greatly influences the efficiency of project implementation. In Iran, traditional design-bid-build (DBB) is commonly used for highway construction projects; however, DBB leads to problems such as cost overruns, delays, and poor quality. This study aims to compare the performance of DBB with that of alternative contracting methods (ACM), including design-build (DB) and construction manager (CM) methods, for highway projects in Iran. A survey was conducted to determine the most important decision-making criteria for selecting the appropriate PDS to use in highway projects. The survey, conducted by postal questionnaire, aimed to empirically validate the reliability of the model. In the survey, all the conditions for imposing the effective criteria were considered, and ultimately a model using the analytical hierarchy process (AHP) was developed to rank the PDSs for highway construction projects in Iran. The results showed that DB is most often the optimal method. The research can be used to prepare a model that can help project owners make sound decisions about the best PDS.