Since the energy crisis in the 1960s, crucial research and activities were spurred to improve energy efficiency and decrease environmental pollution. To deal with the various problems the construction industry are facing, the concept of green buildings (GBs) has been gradually shaped and put forward all over the world, and green building rating systems (GBRSs) have been developed. The concept of GBs covers a wide range of elements, and its definition is constantly updated as the construction industry develops. This paper compares the development of backgrounds and statuses of green building development in various countries. It also presents an overview of the green building development situation within these countries, summarizing two influences for GB development: one external and the other internal. External factors include GB development policy support, economic benefits, and certification schemes. Internal factors are the development and application of GB technology, the level of building management, and how users interact with the GB technology. Currently, 49 worldwide green building standards and application have been sorted out, including 18 standard expert appraisal systems. Moreover, it discusses the research results and lessons learned from green building projects in different countries and summarizes their achievements and challenges. To correctly understand and use green building technology, it is essential to improve the policy and incentive system, improve the professional quality and technical ability of employees and accredited consultants, constantly develop and update the evaluation system, strengthen technological innovation, and integrate design and management. This paper aims to draw a clear roadmap for national standard development, policy formulation, and construction design companies, provide solutions to remove the obstacles, and suggest research direction for future studies.

Global greenhouse gas (GHG) emissions from the construction industry continue to increase at an annual rate of 1.5%. It is particularly important to understand the characteristics of the building life cycle to reduce its environmental impact. This paper aims to assess the environmental impact of prefabricated buildings and traditional cast-in-situ buildings over the building life cycle using a hybrid model. A case study of a building with a 40% assembly rate in Japan was employed for evaluation. It concluded that the total energy consumption, and carbon emissions of the prefabricated building was 7.54%, and 7.17%, respectively, less than that of the traditional cast-in-situ building throughout the whole life cycle. The carbon emissions reduction in the operation phase reached a peak of 4.05 kg CO2/year∙m2. The prefabricated building was found to cost less than the traditional cast-in-situ building, reducing the price per square meter by 10.62%. The prefabricated building has advantages in terms of reducing global warming, acid rain, and health damage by 15% reduction. With the addition of the assembly rate, the carbon emissions and cost dropped, bottoming out when the assembly rate was 60%. After that, an upward trend was shown with the assembly rate increasing. Additionally, this study outlined that the prefabricated pile foundations is not applicable due to its high construction cost and environmental impact.

Abstract:The construction of a building may change the microclimate in the vicinity, and planning indicators in a master plan may directly affect the outdoor physical environmental quality in residential areas. An inappropriate plan for a site may accelerate wind and intensify vortexes over places on the pedestrian levels, which leads to an adverse outdoor environment. Therefore, the design of a cluster of buildings should not focus only on the buildings but also provide a good outdoor environment around the buildings. To tackle the problem of inadequate wind environment, the relationship between the building's floor area ratio and height was identified in this study as the main planning indicator to be examined on its effects on the outdoor wind environment. A computational fluid dynamics (CFD) model was hence developed to simulate the wind conditions generated by some typical site layouts with different values for planning indicators under relevant weather conditions, which were typical of those in Hangzhou, China. The simulated wind conditions are assessed using the wind speed ratio over the whole area of the building cluster at the pedestrian level. The effects on the local wind condition due to the varying of the planning indicators are discussed whilst considering the potential construction costs. The indicators resulting in better external conditions are highlighted in the conclusion as the recommendation which could be used as a rule of thumb by architects and planners at the master planning stage. The study disproves the common belief in the practice that a lower floor area ratio means fewer buildings and therefore greater external comfort. In fact, the higher the building, the greater the outdoor comfort wind zone for pedestrians. However, the increment in comfort area is limited to buildings extending from 25 to 30 levels.