Demel has come back from adversity, battling his way through an injury-plagued first season in east London to make 32 appearances in 2012/13.
"Every player had a part to play this season," he told West Ham TV. "You saw on Sunday that Modibo Maiga came on after a while on the bench and he delivered a good ball for Kev [to score his hat-trick goal with a header].
"This is the atmosphere in the team, everyone gives their best and we know we have to continue to work, because next season will be harder.
"I think it was a good season for me. My first season was difficult because I went through many injuries, but you can feel that good atmosphere in the team so it was pretty easy to come back in.
"I'm quite happy for my season. I played many games, but without my teammates that would not be possible."