Muhammad Tarique Lakhiar0000-0002-4275-5810Shalini SanmargarajaVignes Ponniah0000-0002-9930-3823C.H. LimOlanrewaju AbdullateefAnselm Dass Mathalamuthu2025-09-122025-09-122025-06-0410.48084/etasr.9916https://dspace-cris.utar.edu.my/handle/123456789/11337This study evaluates the energy efficiency of a conventional office building in Malaysia through the implementation of passive and active Energy Conservation Measures (ECMs). The retrofitting strategies included roof insulation, shading devices, HVAC optimization, and LED lighting upgrades, targeting key inefficiencies in the building's baseline energy performance. The energy modeling is performed with the eQUEST tool. Implementing ECMs demonstrated a 59.58% reduction in energy consumption contributing to reducing the annual usage from 292,330 kWh to 118,170 kWh, and additionally achieving CO₂ emission reductions of 132,013.28 kg. The payback period of 3.65 years highlights the economic feasibility of these measures. The annual cost savings reached MYR 88,647.44. The findings emphasize the importance of integrating passive and active strategies to optimize energy performance, reduce environmental impact, and enhance sustainability in office buildings. © by the authors.enCO₂ emission reductionenergy conservation measuresenergy efficiencyequestpassive and active strategiessustainable buildingsjournal-article