In the field of architecture, lighting is regarded as one of the primary contributors to energy consumption. Achieving energy efficiency in lighting through appropriate design is a critical strategy for lighting retrofit projects. The goal of this study is to investigate evaluation methods for near-zero-carbon lighting retrofits in existing office buildings. By examining area-lamp count charts that simultaneously meet illuminance requirements and energy consumption limits and statistically calculating the single-lamp service area for each chart, a faster, simpler, and more accurate method is provided for near-zero-carbon lighting retrofits in existing office buildings, ultimately reducing retrofit costs. This study demonstrates that there are three simple and direct methods for determining the necessary number of lighting fixtures to be retrofitted in existing office buildings for near-zero-carbon lighting retrofits. The first method is the luminous flux calculation, the second is the simulated illuminance chart method, and the third is the single-lamp service area method. The research results indicate that when the evaluation methods proposed in this study are applied in the "Energy Efficiency Assessment Subsidy Operation and Net-Zero Demonstration Program for Existing Public Buildings in the 112th Fiscal Year," they can ensure that the lighting requirements and energy-saving standards in retrofit spaces are met, allowing for a rapid and accurate determination of the required number of lighting fixtures, thus reducing the overall retrofit budget. Using the Net-Zero Demonstration Program as an example, the overall lighting retrofit budget can be reduced by 60%, saving up to 19,238,000 yuan. Furthermore, for near-zero-carbon lighting retrofits in existing office buildings using LED lighting fixtures, this study recommends setting the Minimum Energy Performance Standards (MEPS) value at 100lm/W or higher and using energy-efficient certified fixtures to ensure that the retrofit meets both energy-saving and illuminance requirements, thereby achieving the goal of near-zero-carbon lighting retrofits.