Green buildings are developing rapidly in China. By June 2016, projects that obtained the green building evaluation label had reached 4,314, with a cumulative floor area exceeding 500 million square meters. Developing green buildings as a national strategy is leading the construction sector forward on the path of sustainable development. To ensure the healthy and sustainable development of green buildings, an indispensable task is being carried out that will have a significant impact on the future of green buildings—this is the post-occupancy evaluation of green buildings.

A Different Kind of Green Building Evaluation

Green buildings are energy-efficient buildings that achieve “four savings and one environmental protection” throughout their life cycle. Currently, green buildings recognized in China are assessed according to the Green Building Evaluation Standard and similar criteria, which mainly focus on whether the design and construction phases meet green standards, but evaluation of the green performance after operation is clearly insufficient. According to statistics, among green buildings with a green evaluation label, less than 7% have obtained the green building operation label. In other words, evaluation throughout the entire life cycle of green buildings still needs to be strengthened, and it is against this background that post-occupancy evaluation has gradually received special attention.

It is not enough to merely meet the star-rating standard at the design stage; rather, after the building is completed, operational data should be used to assess the building's energy efficiency, comfort of use, and so on. Evaluating based on the final use effects and actual quantitative usage conditions—this is the post-occupancy evaluation method for green buildings, said Jiang Yi, academician of the Chinese Academy of Engineering.

Researchers point out that the Green Building Evaluation Standard does include evaluation criteria for the operation of green buildings, but it mainly focuses on evaluating whether the technologies or measures adopted by green buildings are in place, whereas the focus of green building post-occupancy evaluation is different. Post-occupancy evaluation is a comprehensive assessment combining subjective and objective aspects of the integrated implementation effects of all technologies and measures of a green building after their application during the project operation phase, satisfaction with the completed use, and human behavioral influencing factors. It generally does not need to consider whether individual technologies or measures are in place, but it does include other possible influencing factors in the application of individual technologies or measures, and thus leans more toward performance-based evaluation.

Obviously, the content of green building post-occupancy evaluation is more detailed and its reference items more diverse.

Reasons for the Delay in Post-Occupancy Evaluation

China's first Green Building Evaluation Standard was formulated and promulgated in 2006, and the green evaluation label system began implementation in 2008, with the first batch of green building evaluation labels issued. Overall, green buildings have only been developing for about ten years, and most green buildings that obtained labels have been in operation for less than ten years. This is the basic background for the small number of green building operation labels and the delay in post-occupancy evaluation.

However, industry insiders analyze this in more specific and in-depth terms. Based on comprehensive industry views, the specific reasons for the small number of operation evaluation labels include: on the one hand, because there were few projects that obtained design labels in the early period, only in recent years have projects gradually met the conditions for applying for operation labels one year after completion; on the other hand, after project completion the project entity changes—especially for residential buildings, where the project entity shifts from the construction unit to the property management unit. Some property management departments cannot meet the requirements for applying for operation labels due to limited management levels, or are simply unaware that they should continue to apply for operation labels. In addition, some projects applied for design labels merely to enhance sales competitiveness, and after obtaining substantial returns and completing sales tasks, they no longer cared about the actual later implementation. These factors have caused the “actual effects” of green buildings to fail to manifest.

This analysis conforms to the actual situation and reveals some problems existing in the development of green buildings. Green building operation evaluation is already lagging, and the slow pace of post-occupancy evaluation as an evaluation system based on operation seems to be within reason.

At present, green building post-occupancy evaluation in China has just started, with only some case studies, or even studies of certain aspects of some projects, still far from establishing comprehensive evaluation methods and technical means for implementation effects during the operation phase.

The evaluation system for green buildings has always been a concern of experts and scholars; indeed, it can be said to be a cutting-edge issue in green building research. In recent years, research on post-occupancy evaluation has gradually become a hot topic, with more and more people expressing opinions on it.

According to a review of the literature, in the early years of the 21st century—that is, the initial stage of green building development in China—the concept of green building post-occupancy evaluation was still unfamiliar, even among green building researchers. At that time, attention to green building evaluation systems focused first on introducing foreign experience and, based on these foreign systems, making suggestions for establishing China's evaluation system. An earlier example is Li Luming's 2002 A Brief Survey of Foreign Green Building Evaluation Systems, which introduced the development history, evaluation methods, and respective characteristics of green building evaluation systems in the United States and other major Western countries, hoping to provide reference for establishing China's green building evaluation system. Subsequent research compared the UK's BREEAM, the US's LEED, and GBC's GBTool, and through analysis of green building implementation in China, proposed that green building assessment must conform to China's national conditions and constructed basic evaluation indicators for green buildings.

Thereafter, under the understanding based on the full life cycle of green buildings, the concept of post-occupancy evaluation was proposed. For example, in a paper submitted to the International Conference on Intelligent, Green and Energy Efficient Buildings in 2009, Yin Bo and others designed a full life cycle comprehensive method including feasibility study, design, construction, operation, post-evaluation feedback, and recycling/reuse phases, and established a multi-level comprehensive indicator system.

With the development of green buildings in China, post-occupancy evaluation has become a research subject for many researchers, and results on this topic continue to emerge, offering suggestions for improving China's green building evaluation system. These studies not only laid the foundation for post-occupancy evaluation in terms of technical methods and theory, but also promoted its emergence in practical work.

Post-Occupancy Evaluation Is Coming

The development of green buildings is a process of continuous deepening. In the past, it was inevitable that people focused on green evaluation during the design and construction phases; now, focusing on the operation and post-occupancy evaluation of green buildings is also necessary, reflecting different priorities at different stages.

In fact, the 2014 revision of the Green Building Evaluation Standard already highlighted operation standards. In the new version, evaluation is divided into two stages—design evaluation and operation evaluation—and the evaluation method was adjusted to score evaluation indicators and determine the rating by total score. Not only does the Green Building Evaluation Standard include content on operation evaluation, but relevant departments have also issued special documents, such as the 2009 Supplementary Explanation of the Technical Rules for Green Building Evaluation (Operation and Use Part). In particular, in December 2016 the Ministry of Housing and Urban-Rural Development approved the Technical Code for Operation and Maintenance of Green Buildings, effective from June 1, 2017. Industry experts believe that the Technical Code for Operation and Maintenance of Green Buildings conforms to China's national conditions, establishes for the first time a comprehensive efficiency commissioning system for green buildings, specifies key technologies and implementation strategies for green building operation and maintenance, and establishes an evaluation indicator system for green building operation management, which is conducive to optimizing building operation and effectively improving the operation and management level of green buildings. These show the foresight of the Ministry of Housing and Urban-Rural Development in developing green buildings and its efforts to continuously improve the evaluation system.

While improving operation evaluation, green building post-occupancy evaluation has also become a task valued by the state and relevant departments. In June 2014, the Ministry of Housing and Urban-Rural Development's special project “Post-Occupancy Evaluation and Survey of Green Building Effects in China” passed acceptance. The project had actually been completed the previous year. The research team studied foreign green building post-occupancy evaluation practices and conducted field surveys of 130 building projects in China that had obtained green building design labels or operation labels, producing reports such as the Research Report on Post-Occupancy Evaluation and Survey of Green Building Effects and the Research Report on Post-Occupancy Evaluation Methods. Subsequently, in July 2016, the National Key R&D Program special project “Research and Application of Post-Occupancy Evaluation Methods for Green Building Performance Based on Actual Operation Effects,” led by Tsinghua University, was approved, with national special funding of 25 million yuan. The purpose of increasing research efforts is to provide a basis and reference for the formulation of relevant policies.

Also in 2016, the Science and Technology and Industrialization Development Center of the Ministry of Housing and Urban-Rural Development, together with the China Architecture Design & Research Group and other units, completed the Technical Guide for Green Building Post-Occupancy Evaluation, covering major aspects such as “land saving and outdoor environment,” “energy saving and energy utilization,” “water saving and water resource utilization,” “material saving and material resource utilization,” “indoor environmental quality,” and “operation management.” The compilation of the Technical Guide for Green Building Post-Occupancy Evaluation has guiding significance for conducting post-occupancy evaluation and has made technical and theoretical preparations for its large-scale implementation.

The degree of greenness of a green building depends crucially on its operational effects, and post-occupancy evaluation is an important link in promoting the implementation of green buildings. The large increase in green buildings is also strengthening the impetus for post-occupancy evaluation. It can be said that the objective environment of green building development is calling for the emergence of post-occupancy evaluation, and the high attention it has received in recent years indicates that green building post-occupancy evaluation is starting, and its widespread implementation is not far away. As for the specific approach to advancing it, this should already be within the consideration of all parties.