【正文】 and rank ordering problems [25,30]. The various fuzzy decision making tools are more suitable to be implicated in the situation when the criteria cannot be easily quantified. Among all the available technologies, the life cycle assessment tool appears great advantages in solving the sustainable evaluation issue over the other technologies. As the characteristics of this case study, the direct weighting method is preferred in this multicriteria decision making problem. 2. Methodology . The structure of the life cycle assessment tool The legislation and regulations regarding sustainable buildings and environmental affect of construction industry in China are less strict than some other developed countries [31]. In order to test the development process and implication of the life cycle assessment in sustainable design, a case study of an international retailer?s sustainable strategymaking in their Flagship Store in China has been chosen to be applied in this research. The retailer?s objective is to select the sustainable design options with longterm economic benefit and environmental conscious for their future global stores. The chosen case study is a typical multicriteria decision making problem involving longterm economical and noneconomical analysis, therefore it was chosen to test the life cycle assessment tool in practice. The proposed life cycle assessment tool involves the qualitative evaluation from practitioners and the quantitative data from technical engineers and quantity surveyors. Various parties involved in the assessment process allow the tool taking into consideration not only the longterm environmental and economic impacts of the building design options but also the feasibility evaluation of the practitioners. Their data are finally integrated into a single measurement to rank the design options. The integrated tool includes the following steps: 1. Generating sustainable building design options through literature review. 2. Feasibility assessment by practitioners through educational workshops. 3. Technical analysis on life cycle costs and risk levels of design options by technical experts. 4. Multicriteria decision making process to bine multiple evaluations by direct weighting method. . Generating design options The sustainable design options are generated by an indepth literature review on the previous researches and established sustainable design assessment tools. The crossmapping method has been applied to summarise a generic and prehensive design option list. According to the design scope and local environment of the individual project, some options that are not applicable are omitted in order to generate a shopping list for the specific project. Those sustainable design options are presented to the practitioners during workshops in order to educate the decision makers about the influence of their decision making on the environment so that they will take more social responsibility. They will also be requested to evaluate the feasibility of the design options on the shopping list under industrial environment. . Data collection The selection of the optimum sustainable design options in the project depends on multiple factors such as: the political concerns of the retailer and the technical issues including life cycle costs and risks. The data e from several parties in the following steps. The first section involves a group decision making process. Workshops with some key executives of the retailer have been arranged on a weekly basis in order to evaluate feasibility of the design options under industrial environment. A questionnaire is designed for the workshops to help the practitioners to rank the options according to the retailer?s priorities. A duepriority matrix has been designed to collect the group decisions for the workshop as shown in Fig. 1. Each of the practitioners evaluates the given options by two priorities: the environmental benefit and the ease of implication. The environmental benefit of the options can be assessed by a 3point scale from low to high. The ease of implication can be assessed by another 3point scale from easy to hard. The decision makers in the workshop will tick the appropriate box in the matrix to evaluate each option. For example, the question to ask the practitioner in the interview survey for each design option is: Environmental Benefit Low High Ease of Implaementation Easy Hard Fig. 1. Duepriority matrix. N. Wang et al. / Building and Environment 45 (2021) 1415–1421 1417 ??For design solution option 12, how to evaluate the ease of implication and its environmental benefit in practice??? (please tick the appropriate choice from Fig. 1). Each of the nine boxes in the duepriority matrix represents a number so that the overall feasibility score of the option can be obtained. The scoring system designed for the duepriority matrix is shown in Fig. 2. The final result of the workshop is decided by the overall feasibility score Sw of each option, which is calculated by summarising each of the decisionmakers? score on the ith option Si divided by the number of decision makers. Sw XSi=n (1) The feasibility of the suggested design options can be ranked by the preferences of the decision making group. Another data collection step involves technical evaluation of the life cycle costs and risk levels of the design options. The experts evaluated the options against these criteria based on their experience and historical data. For each option, the life cycle cost evaluation includes the estimates of the initial capital expenditure and operational cost which are scored according to the cost ranges they fall in. As it is the initial stage of the project development, it is impossible to give a very accurate cost estimate without detailed design information. The quantity surveyor can only give a cost range f