Towards nearly zero energy buildings: energy and environmental analysis of retrofit scenarios for a residential building in İzmir

Abstract Nearly Zero-Energy Buildings (nZEBs) have emerged as a viable solution for improving building energy efficiency, with designs adapted to local climatic conditions. This study examines the transformation of a single-glazed residential building in İzmir, which has a Mediterranean climate, into an nZEB. Three retrofit scenarios were proposed, integrating both active and passive energy efficiency measures, and energy simulations were conducted using DesignBuilder (DB) to evaluate the building’s energy performance and emissions. The reference building’s annual net energy consumption was 177.55 kWh/m 2 /year, net primary energy consumption 281.57 kWh/m 2 /year, and CO 2 emissions 88.54 kgCO 2 /m 2 /year. Scenario 3 (S3) was the most effective, reducing net primary energy consumption by 82.39% to 49.61 kWh/m 2 /year and achieving the highest energy class. Energy efficiency measures significantly enhanced performance, with LED lighting providing the highest energy savings, while improved building envelopes reduced heat loss by 74%. In all scenarios, natural gas consumption was eliminated, leading to CO 2 emission reductions of 58% in Scenario 1 (S1), 66% in Scenario 2 (S2), and 80% in S3. These findings demonstrate that achieving nZEB standards in residential buildings in a Mediterranean climate can reduce heating and cooling energy consumption by over 50%, offering substantial energy and environmental benefits.