The energy service industry is a newly emerging industry in Taiwan, where related regulations and measures are still at an immature stage. The business operation models include being a motivator in regard to energy conservation, becoming an ESCO, or developing strategies covering both areas. The implementation will help present energy users to break through existing bottlenecks involving: funds, manpower, technology, and recycling term; change the environment where the Government is currently the main motivator; and attract private companies to participate in energy saving and carbon reduction. First, topics for in-depth interviews were established in order to obtain a better understanding of the operational environment of ESCOs in Taiwan, including any obstructions encountered during the development of the ESCO industry. Second, in-depth interviews were carried out with selected ESCOs via explorative research and quantitative methods. The interview data were analyzed and discussed. The following results were obtained regarding the domestic ESCO industry: 1. The status of current development and business opportunities is promising. 2. Factors affecting current development include the lack of regulations, subsidizing plans, third party authentication, energy-saving technologies, and financing solutions. 3. The financing difficulties include: insufficient collateral, sound financial reports, or banks¡¦ understanding of the ESCO industry. 4. The key success factors for the domestic ESCOs to enter the global ESCO market include: the accuracy of the energy-saving reports and income estimates, provision of integrated energy-saving technologies, and utilization of the small and medium business credit guarantee funds and loans. 5. Business models that best suit the development of domestic ESCOs include: sharing energy, performance guarantees, and equipment lease.