  This paper is devoted to a non-perturbative renormalization group (NPRG)
analysis of Model A, which stands as a paradigm for the study of critical
dynamics. The NPRG formalism has appeared as a valuable theoretical tool to
investigate non-equilibrium critical phenomena, yet the simplest -- and
nontrivial -- models for critical dynamics have never been studied using NPRG
techniques. In this paper we focus on Model A taking this opportunity to
provide a pedagological introduction to NPRG methods for dynamical problems in
statistical physics. The dynamical exponent $z$ is computed in $d=3$ and $d=2$
and is found in close agreement with results from other methods.
