A Geometry Simplification Strategy for Early-Stage Energy-Oriented Design of Office Buildings in Hot–Humid Regions: Application to Orientation Optimization

During the conceptual design phase, detailed geometric models are often unavailable, hindering energy-driven decisions for five-story office buildings. This paper proposes a geometry simplification strategy for office buildings in hot–humid regions using only length and width. Based on 130,976 geometric parameter combinations, stratified into an 80% selection set and a 20% validation set using four-dimensional parameter stratification, a standardized rectangular energy model is built, and EnergyPlus simulates orientations from 0° to 179° (1° step), totaling 23.6 million runs. Three simplification methods are compared: aspect ratio, floor area, and the proposed length–width combination. The length–width combination simplification strategy achieves an average relative energy deviation of 6.89% (6.87% on the held-out validation set), with a reduced maximum deviation on the held-out validation set (27.70% for the length–width method vs. 32.07% for the floor area method), thus meeting conceptual design accuracy requirements. Using this simplified model, the optimal orientation is identified as 0° (true south–north), accounting for 83.14% of cases. For the three representative geometric configurations examined, a near-optimal orientation band of ±15° around their respective optimal orientations is identified, within which the energy penalty remains below 1% of the minimum, providing designers with potentially flexible guidance that accommodates site-specific constraints without compromising energy performance. The orientation range 39–86° is not recommended when energy performance is prioritized, as it contains over 99% of worst-case orientations. The proposed strategy enables rapid energy estimation and orientation guidance from basic parameters, shifting energy-efficient design from late verification to early-stage driving, and providing quantifiable support for early-stage energy-efficient design as the foundation for subsequent nearly zero-energy building development in hot–humid regions.