Hossein Bakhtiari's research focuses on achieving energy efficiency and improving thermal comfort in historic buildings connected to the district heating network focusing on efficient control strategy solutions for HVAC system. The case study of the research is the historic City Hall in Gävle City in Sweden, which has been refurbished to an office building. Hossein Bakhtiari is also a member of the environmental council at Gavlefastigheter Company in Sweden which has the mission of implementing the new regulation for climate declaration of newly constructed buildings by the company.