DescriptionTime-to-solution has historically been the primary optimization objective for HPC applications. A side effect of the resulting accelerated application was typically a reduced energy consumption. Especially in light of the current energy shortage, this side effect is quickly becoming an optimization target by itself. But with dynamic power management, every changing landscape of system architectures it is increasingly challenging to find energy optimal implementations for a specific application. Approaching HPC applications from the energy perspective leads to a range of interesting questions: Is asking for performance portability justified if energy footprint is the primary driver? Can we co-design a minimum energy system geared towards a certain application domain? As HPC is moving from single applications to complex coupled systems, will the same types of optimization recipes hold? And what kind of tools are needed to support the developer’s energy optimization journey? In this minisymposium we bring together experts addressing energy optimization from the application, system and HPC center point of view. With a focus on weather/climate and related applications, the presenters will discuss the impact of low-level application optimization on energy footprint, the impact of different hardware architectures and the support that is needed from an HPC center level.