In recent years, the awareness of sustainable construction has increasingly risen in countries around the world, with the main goal being to avoid depleting energy resources and raw materials and to greatly reduce carbon emissions. Therefore, the selection of eco-friendly building materials becomes a difficult task and choosing the best construction strategy is a complicated process. Most of the studies of the building material selection often focus on optimizing material-related green building scores with budget constraints based on the environmental impacts of those materials. However, these studies do not pay attention to the impact of sustainable materials on two important aspects of a project: The initial investment cost and the total labor-working days. Hence, this study developed a model that optimizes a material mix for buildings considering the building budget, total labor-working days, and material-related green building scores. A case study in Vietnam was conducted to illustrate the effectiveness of the proposed model. This proposed model provides a guidance for decision-makers in selecting approximate materials for buildings toward sustainability.Sustainability 2020, 12, 2769 4 of 19 of materials type, construction strategy, and the Lotus-based green building certification system in Vietnam (Figure 1). toward green buildings. 132 2. Problem Definition 133 2.1. Definition of the Optimization Problem. 134The problem in this study aims to build an eco-friendly material selection integrated platform 135 that will enable building owners and designers to optimize decision making through knowledge of 136 materials type, construction strategy, and the Lotus-based green building certification system in 137 Vietnam (Figure 1).

This article focuses on developing an energy simulation model through Building Information Modeling (BIM) and Building Energy Modeling (BEM)to optimize energy in building design in Vietnam. Reducing the energy consumption in buildings will help reduce operating costs, impact the environment, and increase the efficiency of buildings. However, there is limited research on buildings with complex structures and configurations, detailed surface design, and envelope construction, especially in simulating details through BIM. The author proposes converting from BIM to BEM to simulate energy in buildings and optimize the factors related to building construction in the envelope design of the building. These factors include wall cladding materials, mirror materials, the window ratio on the walls, and other details. This study has effectively created an energy model for a public building, allowing for the calculation of the Energy Intensity Index (EUI) and annual energy costs for various scenarios. By altering factors associated with the design and construction process, the system has the potential to decrease both energy intensity and usage costs for the building. The study results will help designers and building managers improve and enhance energy efficiency in building projects.

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