Decarbonizing residential energy systems through integrated renewable and bioenergy pathways

• Introduces a unified MILP framework coupling electrical and thermal energy optimization. • Demonstrates synergy of bioenergy and battery storage in hybrid renewable systems. • Identifies key economic and policy levers for accelerating residential decarbonization. • Offers actionable insights for achieving resilient, low-carbon home energy transitions. • Enhances grid resilience and reduces reliance on unstable conventional energy networks. Residential energy analyses often optimize electricity and heat separately, masking their tight operational coupling and the cascading effects of technology choices across both domains. This study addresses that gap with a unified mixed-integer linear programming (MILP) framework that co-optimizes capacity sizing and hourly operation across photovoltaic panels and wind turbines (electric generation), geothermal and biogas systems (thermal generation), an air-source heat pump that couples power-to-heat conversion, and lithium-ion battery storage for a four-person dwelling. The model evaluates three policy scenarios designed to assess progressive decarbonization pathways: business-as-usual (BAU) to establish baseline performance, a 50% natural-gas capacity constraint aligned with European Union emission targets, and dual 70% constraints on gas capacity and CO 2 emissions addressing Iran’s energy challenges and ambitious net-zero commitments. Sensitivity analyses examine electricity price and carbon tax thresholds that drive technology transitions. Under BAU, gas-based technologies dominate, yielding 11.66 kg CO 2 daily emissions. Imposing a 50 % gas constraint electrifies heat via the heat pump, reduces emissions by 54 % to 5.4 kg CO 2 , and increases renewable penetration to 47 %. With dual 70 % constraints, renewables supply 95 % of total energy, grid imports decline by 73 %, and daily emissions fall to 0.93 kg CO 2 as battery cycling intensifies eight-fold. Battery storage mitigates short-term power variability, manages peak grid interactions, and enables load-shifting to periods of higher renewable availability, collectively enabling deeper decarbonization under stringent policy constraints. Economic sensitivity analyses reveal critical thresholds: renewables reach cost parity at €0.18 kWh −1 grid electricity prices, and 57 % renewable penetration occurs at €120 tCO 2 −1 carbon taxation. By optimizing electricity, heat, and storage within a single framework, this study identifies practical policy levers—moderate pricing reforms coupled with storage incentives—for economically viable, net-zero-ready residential energy systems.