## 3 Methodology
### Questionnaire  
A questionnaire was designed to explore the feasibility, challenge and barrier of piping prefabrication. The questionnaire was used to verify the generality of the findings from the semi-structured interviews, case studies, and site visits. The objective of this questionnaire includes: (1) general attitude toward the feasibility of piping prefabrication; (2) the influence of some factors on the successful implementation of piping prefabrication; and (3) critical challenges or barriers of piping prefabrication.  
The questionnaire included a total of 18 questions organized into 4 main sections, as shown in Table 1. This questionnaire was distributed to a sample of piping contractors. A brief introduction on piping prefabrication and descriptions of some terms were also attached to the questionnaire to ensure that all the respondents were informed of and were using the same definition and description for each question. These questions were formulated in a neutral way without implying any set propositions.  
During a period of three months, the questionnaire was distributed to 411 respondents. All the respondents are practitioners come from piping contractors. A total of 48 responses were received, all answers were checked to verify the completeness and validity. Therefore, these 48 samples were used for the analysis. These figures represent a valid response rate of 11.7%, which is adequate for the data analysis. Time and resource limited the increase of response rate. A similar survey also reported low response rate (response rate of 2.9%) because of the large population of possible respondents [31]. However, the diversity of the collected sample can be considered representative for the piping contracting industry. The respondents cover large, small and medium piping contractors such as China Construction Industrial & Energy Engineering Corporation, Shanghai Installation Engineering  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Category** & **Questions** & **Provided Values** \\ \hline \multirow{4}{*}{General information} & General information of those people surveyed that works in MEF firms. & For example, four options (<3 years, 3–5 years, 5–10 years, and >10 years) were provided for work experience. \\ \cline{2-3}  & The number of piping projects participated? & \(<\)3, 3–5, 5–10, and >10 \\ \cline{2-3}  & Does the designer provide the BIM model in the project participated? & Yes/No \\ \hline \multirow{4}{*}{Level of the feasibility of piping prefabrication} & The feasibility of piping prefabrication in different \\ \cline{2-3}  & The feasibility of piping systems. & \\ \cline{2-3}  & The feasibility of piping prefabrication using & \\ \cline{2-3}  & different piping connection method & \\ \cline{2-3}  & The feasibility of piping prefabrication in different & \\ \cline{2-3}  & types of project & Likert scale (1–5) \\ \hline \multirow{4}{*}{Level of the influence of some factors to piping prefabrication} & Influence of BIM to piping prefabrication & \\ \cline{1-1} \cline{2-3}  & Influence of integrated project delivery method such & \\ \cline{1-1} \cline{2-3}  & as EPC to piping prefabrication & \\ \cline{1-1} \cline{2-3}  & Influence of early involvement of manufacturers and & \\ \cline{1-1} \cline{2-3}  & distributor in the project. & \\ \hline \multirow{2}{*}{Challenges and barriers} & The challenges and barriers of piping prefabrication. & Multiple-choice questions with ten options such as standardization of design, policy, and availability of fitting and valves. \\ \cline{1-1} \cline{2-3}  & & fitting and valves. \\ \hline \hline \end{tabular}
\end{table}
Table 1: Questionnaire Design.  
Group Corporation, and Dalian Zhongying Mechanical, Electrical & Plumbing Corporation. Figure 3 shows the work experience and the number of piping projects participated of respondents. 58% of respondents have a work experience above three years. 73% of respondents have completed more than three piping projects. The rich experience accumulated in practice will give a result of high quality.