This paper presents building design strategies for reducing embodied energy and embodied carbon dioxide emissions as developed within the International Energy Agency’s Energy in Buildings and Communities Programme. The design strategies are illustrated using three case studies of design optimisations of building elements, the building structural system and the whole building. The first case study shows the environmental optimisation of a curtain wall facade element using bio-based materials. The second case study presents the optimisation of the structural system for a residential building by lightening the floor structures through utilising ultrahigh-performance concrete and vertical elements with reduced cross-section. The third case study presents an alternative design for a passive-design family house in Prague in the Czech Republic, leading to hybrid construction of light prefabricated concrete elements, a timber frame and a timber-based building envelope.