Fabby Tumiwa is the Chief Executive Officer (CEO) of the Institute for Essential Services Reform (IESR) and an energy transition strategist. A founding member of IESR since 2006, he has led the organization since its establishment, guiding its strategic direction to advance sustainable energy policy, accelerate renewable energy deployment, and support Indonesia’s transition toward a low-carbon energy system.

With more than 20+ years of experience in energy and climate policy and regulation, Fabby is a strong advocate for renewable energy and energy transition. He advises Indonesian government agencies, businesses, non-governmental organizations (NGOs), and multilateral development institutions on electricity regulation, renewable energy policy, energy efficiency, and climate change policy. He served as Indonesia’s delegate to international climate change negotiations from 2006 to 2017, was a member of the National Council on Climate Change Working Groups (2009–2014), and sat on the Steering Committee of the Indonesia Climate Change Trust Fund (ICCTF) (2015–2019). 

He holds degrees in Electronic Engineering from Satya Wacana Christian University, studied Extractive Industries Governance from Central European University, and Energy and Climate Policy from Tufts University’s Fletcher School.

Beyond his core professional work, Fabby has played an active role in several national and international initiatives. He was one of the founders of the Indonesian Energy Conservation and Energy Efficiency Society (MASKEEI), Indonesia Solar Energy Association (ISEA) in 2016 in which he served as its Chairman from 2021 to 2024. He previously served as a member of the Extractive Industries Transparency Initiative (EITI) Steering Committee (2011–2015). He is an alumnus of the LEAD Fellowship (2007) and the Eisenhower Fellowship (2009), was a member of GoJek Indonesia’s Sustainable Advisory Council, and an advisory board member of the Indonesia Energy Transition Partnership (ETP). 

In 2023, he was appointed to the High-Level Consultative Group (HLCG) of the Energy Transition Accelerator, an initiative by the US State Department, the Rockefeller Foundation, and the Bezos Earth Fund. In 2024, he was appointed as a member of Green and Low Carbon Expert Network (GLEN) of BRIGC. Since 2025, he has served as an IEA Technology and Innovation Advisory Board member and a member of the World Economic Forum (WEF) Energy and Industry Transition Intelligence Advisory Board.