Decision feedback equalizers (DFE) employing energy constraints have been successfully used to limit the feedback of wrong decisions that lead to the well known error propagation phenomenon. This paper extends the energy constraint formulation proposed for the scalar DFE, to the class of block memoryless DFE structures that employ zero-padding transmission redundancy. We further show how to make use of fast order recursive relations in order to obtain the filters efficiently. Computer simulations verify the improved BER performance of the proposed scheme over its unconstrained block DFE counterpart.