This paper presents the formulation of a new methodology to design adaptive structures. This design method synthesises structuralconfigurations that are optimum hybrids between a passive and an active structure. An optimisation scheme searches for an optimalmaterial distribution and actuation layout to minimise the structure whole-life energy which consists of an embodied part in thematerial and an operational part for structural adaptation. Instead of using more material to cope with the effect of loads, here,strategically located active elements redirect the internal load path to homogenise the stresses and change the shape of the structure tokeep deflections within required limits. To ensure the embodied energy saved this way is not used up to by actuation, the adaptivesolution is designed to cope with ordinary loading events using onlypassive load-bearing capacity whilst relying on active control todeal with larger events that have a smallerprobability of occurrence. The design methodology has been implemented for staticallydeterminate and indeterminate reticular structures. However, the formulation is general and could be implemented to other structuraltypes. Numerical simulations on a truss system case study confirm that substantial savings up to 50% of the whole-life energy can beachieved by the adaptive solution compared to a passive solution designed using state of the art optimisation methods.