This paper introduces a simplified and scalable heat-flow based approach for form, massing and orientation early stage design of high-performance buildings (HPBs). A reference building model (RBM) is first defined with pre-selected building materials and HVAC systems for the intended climate and site conditions. The energy performance of this RBM is estimated by whole building energy simulation. Heat fluxes from the enclosure are extracted from RBM simulation. A simplified and physics-based correlation model was developed to predict how these fluxes would be affected by the shape of the building geometry, window-wall ratio (WWR), and orientation of a proposed building design, which can significantly differ from the RBM. Based on building space heat balance, the predicted heat fluxes were then used to predict the energy consumption of the proposed building.