Multi-objective daylight and energy-use optimization of the office building in climatic conditions of Ukraine

Bogdan Kutsevych, Keiichiro Taniguchi
Energy Efficiency First, Volume 2, 2025, 100007
https://doi.org/10.1016/j.eef.2025.100007

Abstract
Paper investigates and proposes academically proven method for daylight and energy-use optimization of an office building (OB) in climatic conditions of Ukraine aiming to achieve optimal values of Daylight Factor (DF), Daylight Glare Probability (DGP) and minimal Energy Consumption (EC). The method employs parametric simulation modelling in Grasshopper software and includes: DF and DGP image-based simulation, EC simulation. The optimization process is based on using evolutionary algorithms for Multi-Objective Optimizations (MOO). The analysis identifies optimal values of Window-to-Wall Ratios (WWR), window Length-to-Height Ratios (LHR) and shading device depths for the south-facing facades of OB in Kyiv and Odesa, Ukraine, representing distinct climatic zones. The study demonstrates that proposed building façade optimization combined with the implementation of daylight control sensors can lead to 4–5 % reduction in EC. Additionally, it was justified that façade design decisions should vary depending on two climatic zones of Ukraine. Furthermore, the correlation between higher WWR and higher DF & DGP was noticed. The following common trends were observed for both locations for optimal design variables: WWR is in 55–65 % range; LHR ratio is approximately 2:1; shading device depth is 0.5–1 m. As for the differences between optimization of OB façade design for Kyiv and Odesa, informed by optimal values of DF, DGP and minimal EC, Odesa requires smaller WWR and larger solar shading than Kyiv. It is explained by milder climatic conditions of Odesa – higher winter temperatures and higher solar radiation. Optimal WWR ratios in Odessa are 5–10 % smaller than in Kyiv, while at the same time optimal shading device depth is 10–20 % deeper than in Kyiv.