Sheffield, who is a senior account manager at Oxford International and a C&IT A-Lister, said: "As a CSR representative at Oxford International and now on the Eventia corporate responsibility working party, I am keen to work towards minimising the impact of the events industry."
Jones works in HR and CSR at crewing company Gallowglass and said that he could bring "another dimension to discussions" about sustainability.
Meanwhile, First Protocol account manager Melanie Delaplanche has left the working party to go on maternity leave. She is temporarily replaced by First Protocol chief executive Richard Waddington.
The working party comprises ten Eventia members including venues, hotels and agencies and it is seeking additional members.