We solve the energy balance equation for a coronal loop that is heated simultaneously by field‐aligned currents and by runaway electrons accelerated by a DC‐electric field. We combine hard and soft X‐ray observations from theComptonGammaRayObservatoryandYohkoh, respectively, and compute the temporal variation of the DC‐electric field strength during the flare impulsive phase. We find that Joule heating by coronal currents dominates the flare energy balance during the preflare and impulsive phases, while collisional heating by runaway electrons becomes significant only during the hard X‐ray impulsive phase. ©1996 American Institute of Physics.