David Wagner hailed the hard work put in by his players both in training and at St Andrew's as he celebrated his first win as Huddersfield Town head coach.
A first-minute goal by Joe Lolley and a late second from Nahki Wells sealed a 2-0 triumph and lifted Town out of the Championship relegation zone .
Wagner, in charge for the third time, said the bonus of a clean sheet, Town's first in seven games, made it a "perfect day".
He added: "I am very pleased about the win and proud of the squad. It was another good performance and another step to where we want to be.
"We scored a very good first goal through playing football on the ground, and our second was a very good transition goal.
"The guys did a very good job. We looked at the way we wanted to play, and didn't worry too much about Birmingham.
"There were a few occasions where we lost the ball in the first half, but in the second half, we only gave them once chance, so the defence was pleasing.
"I could see the passion I want the squad to bring to the pitch. Everyone knows if you work hard, which my players did, you will get results. This was a perfect day for us."