What the reader will find in this paper is an explanation of our: • approach to sustainability • responsibilities for considering safety, environmental protection and environmental sustainability in developing the IPSP • responsibilities for establishing the rationale for alternatives to electricity projects proposed in the IPSP • criteria used for integration of the elements of the long-term plan [...] The emphasis is on a long-term perspective and concern for the well-being of future generations, and includes the phase out of coal-fired generation, the development of a culture of conservation in Ontario and a substantial increase in renewable sources. [...] In order for the OPA to assess the sustainability of the IPSP in an integrated manner, a comprehensive view of the economic, social and environmental implications of the plan is necessary. [...] Flexibility: This includes the flexibility of options in the future and the robustness of the plan to be sufficiently adaptable to a range of future scenarios. [...] These elements came together in the Electricity Restructuring Act, 2004, which, by amending the Electricity Act, 1998, created the OPA, the Conservation Bureau within the OPA, and the IPSP as a key responsibility of the OPA.