This paper discusses the design and implementation of a domainspecific language (SHEP) for modelling energy optimal pumping systems (realizing specific flows and pressures). The optimization problem (specified as a SHEP model) is transformed into a corresponding mixed-integer linear program which can be solved by standard MILP-solvers. The solution together with the original model are transformed into executable simulation models (e. g. MODELICA or MATLAB SIMULINK).